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  • Column liquid chromatography  (88)
  • gene expression
  • Springer  (115)
  • American Meteorological Society
  • Periodicals Archive Online (PAO)
  • 1995-1999
  • 1990-1994  (115)
  • 1935-1939
  • 1991  (115)
Collection
Keywords
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  • Springer  (115)
  • American Meteorological Society
  • Periodicals Archive Online (PAO)
  • Wiley-Blackwell  (18)
Years
  • 1995-1999
  • 1990-1994  (115)
  • 1935-1939
Year
  • 1
    Electronic Resource
    Electronic Resource
    Morphological, biochemical and molecular changes during ectomycorrhiza development (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 321-331 
    Details
    ISSN: 1420-9071
    Keywords: Symbiosis ; ectomycorrhiza ; ectomycorrhiza development ; gene expression ; ectomycorrhizins ; protein patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ectomycorrhiza, a specialized root organ, is the result of a complex interaction leading to a finely-tuned symbiosis between a plant and a compatible ectomycorrhizal fungus. Ultrastructural observations combined with cytochemical and biochemical studies reveal that structural and metabolic changes in the symbiont cells lead to the final phenotype of the active ectomycorrhiza. In the present review these changes are interpreted as changes in gene expression and discussed within the context of ectomycorrhiza development. Recent genetic data indicate that the continued vegetative growth of the ectomycorrhizal hyphae and the root tissues, and their ability to switch to symbiotic organ formation, is basically controlled by developmentally critical genes. The activity of these ‘symbiotic genes’ during the differentiation of ectomycorrhizas is associated with extensive changes in the concentration of particular polypeptides and protein biosynthesis. The present state of knowledge about the developmental biology of ectomycorrhizas allows only speculation about the events during their development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01972073
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  • 2
    Electronic Resource
    Electronic Resource
    Oxygen regulated gene expression in Escherichia coli: Control of anaerobic respiration by the FNR protein (1991)
    Springer
    Antonie van Leeuwenhoek 59 (1991), S. 65-76 
    Details
    ISSN: 1572-9699
    Keywords: anaerobic respiration ; FNR protein ; oxygen regulation ; gene expression ; E. coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molecular oxygen is an important regulatory signal in facultative anaerobic bacteria and controles the expression of a great variety of genes positively or negatively. The expression of anaerobic respiration and of related functions of E. coli is controlled by the positive gene regulator FNR, which activates transcription in the absence of O2. The regulated genes carry a FNR consensus sequence upstream of the promoter. Under the same conditions FNR represses some of the genes of aerobic respiration. The binding to the DNA occurs by an α-helix-turn-α-helix DNA-binding domain. FNR contains 5 cysteine residues, four of which are arranged in a cluster close to the N-terminal end. For the function of FNR as a O2-dependent regulator three of the cysteine residues in the cluster and the residue outside the cluster are essential. FNR binds iron as a cofactor which most likely is involved in the O2-sensing by the protein. The experiments indicate that the cysteine residues are responsible for the binding of the iron. From the protein in vivo two functional states can be differentiated, an aerobic or metal-depleted form and an anaerobic form. Only the anaerobic form acts as a gene activator or repressor. Sensing of O2 or of positive redox potentials by the iron ion is thought to cause the conversion of the two functional states. The FNR protein in addition contains a potential nucleotide binding domain. The significance and function of this site is not clear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00445650
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  • 3
    Electronic Resource
    Electronic Resource
    The human leukemia cell line, THP-1: A multifacetted model for the study of monocyte-macrophage differentiation (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 22-31 
    Details
    ISSN: 1420-9071
    Keywords: Atherosclerosis ; cellular differentiation ; gene expression ; foam cells ; lipoproteins ; phorbol esters ; transcription factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary THP-1 is a human monocytic leukemia cell line. After treatment with phorbol esters, THP-1 cells differentiate into macrophage-like cells which mimic native monocyte-derived macrophages in several respects. Compared to other human myeloid cell lines, such as HL-60, U937, KG-1, or HEL cell lines, differentiated THP-1 cells behave more like native monocyte-derived macrophages. Because of these characteristics, the THP-1 cell line provides a valuable model for studying the mechanisms involved in macrophage differentiation, and for exploring the regulation of macrophage-specific genes as they relate to physiological functions displayed by these cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02041244
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  • 4
    Electronic Resource
    Electronic Resource
    Production of pharmaceutical proteins in milk (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 905-912 
    Details
    ISSN: 1420-9071
    Keywords: Gene transfer ; gene modification ; gene expression ; livestock ; transgenic animal ; pharmaceutical proteins ; milk composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract There is every reason to expect that it will be possible within the next few years to begin to use farm animals to produce large quantities of some of the human proteins that are needed for the treatment of disease. Revolutionary new opportunities for the production of novel proteins in milk have been created by the development of methods for gene transfer. Exploitation of these opportunities depends upon selection and cloning of milk protein genes and identification of the sequences that govern tissue specific hormonally induced expression in the mammary gland. Studies with three genes, ovine β-lactoglobulin, rat β-casein and whey acidic protein of rat and mouse, suggest that they may all meet this requirement. Fragments of the ovine β-lactoglobulin, murine whey acidic protein and rabbit β-casein genes have directed production of novel proteins in the milk of transgenic mice, sheep, rabbits and pigs. The proteins were biologically active and usually co-migrated with authentic proteins. In early experiments, protein concentration was low, but our recent observations suggest that fusion genes containing genomic clones direct production of concentrations of protein that are suitable for commercial exploitation. In the longer term, two approaches may offer the potential of more reliable expression. Control elements capable of directing expression that is independent of site of insertion of the gene, but dependent on the number of copies of the gene, have been identified for a small number of genes. The availability of such elements for the milk protein genes would increase the reliability of gene expression considerably. Alternatively, targeted mutation of genes may allow the insertion of coding sequences within an existing gene so avoiding position effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01929881
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  • 5
    Electronic Resource
    Electronic Resource
    Transgenic regulation in laboratory animals (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 866-877 
    Details
    ISSN: 1420-9071
    Keywords: Transgenic mice ; microinjection ; recombinant DNA ; gene expression ; transcription factors ; chromatin ; homologous recombination ; episomal maintenance ; embryonic stem cells ; germ line ; position-effect ; mosaicism ; globin genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This chapter is an attempt to summarize some commonly accepted and some more subjective opinions about the regulation of transgene expression in laboratory animals. After a short historical introduction, I present some general notions regarding gene structure/function. The spotlight shifts then to the description of the most popular techniques for gene transfer, including the targeted gene replacement. The different approaches are briefly discussed in terms of intrinsic advantages and limitations regarding gene expression patterns. Furthermore, the role of enhancers, promoters and othercis-acting elements such as silencers and dominant control regions as well as their involvement in the chromatin on-off state are discussed on the basis of a specific example studied in our laboratory. The review concludes by presenting recent results and the new perspectives opening in the field of ‘surrogate’ (also called ‘reversed’) genetics. Some problems which remain to be solved both at the technical as well as at the social-ethical level are also briefly presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01929876
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  • 6
    Electronic Resource
    Electronic Resource
    Gene transfer in plants of Brassica juncea using Agrobacterium tumefaciens-mediated transformation (1991)
    Springer
    Plant cell reports 10 (1991), S. 308-314 
    Details
    ISSN: 1432-203X
    Keywords: Agrobacterium tumefaciens ; Brassica juncea ; genetic transformation ; gene expression ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An efficient system for gene transfer into plants of Brassica juncea var. India Mustard, mediated by Agrobacterium tumefaciens. was developed through the manipulation of the culture medium and the use of the appropriate Agrobacterium strain. High frequency shoot regeneration (90–100%) was obtained from hypocotyl explants grown on medium containing 0.9% agarose, 3.3 mg/L AgNO3 and 0.5–2 mg/L BA in combination with 0.01–0.05 mg/L 2,4-D or 0.1–1 mg/L NAA. Of all the Agrobacterium strains tested, A. tumefaciens A208-SE, carrying the disarmed Ti plasmid and a binary vector pROA93, was the most effective for B. juncea transformation. pROA93 carries the coding sequences of the NPTII and the GUS genes, both driven by a common CaMV 35S promoter in two divergent directions. Inoculated explants grown on the selection medium in the presence of 0.5 mg/L BA and 0.1 mg/L NAA gave rise to transgenic shoots at the highest frequency (9%). All Ro transgenic plants were phenotypically normal, but variation in expression patterns of the GUS gene occurred among the transgenic plants in an organ- and tissue-specific manner. Both the NPTII and the GUS genes were transmitted to the R1 seed progeny and showed co-segregation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193148
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  • 7
    Electronic Resource
    Electronic Resource
    Correlations between a nuclear and a mitochondrial mRNA of cytochrome c oxidase subunits, enzymatic activity and total mRNA content, in rat tissues (1991)
    Springer
    Molecular and cellular biochemistry 107 (1991), S. 21-29 
    Details
    ISSN: 1573-4919
    Keywords: mitochondrial biogenesis ; cytochrome c oxidase ; mRNA quantitation ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Cytochrome c oxidase (COX), like other multi-subunit components of the respiratory chain, is controlled by both the nuclear and the mitochondrial genome. In order to find wether there is a close relationship between mRNAs encoded by the nucleus and by the mitochondrion, and between these mRNAs and enzyme activity, we compared six rat tissues (ventricle, liver, m. soleus, m. plantaris, and the white and red portions of m. gastrocnemius). We found a tenfold range for COX activity, a tenfold range for the contents of mRNA III (mitochondrial) and mRNA VIc (nuclear), a threefold range for total [poly(A)+] mRNA content and a sevenfold range for total RNA content in these tissues. The ratio of mRNA III to mRNA VIc was equal in each tissue, indicating the presence of a mechanism that coordinates the two genomes. There was a good correlation between mRNA content and COX activity (r = 0.78 for VIc, r = 0.77 for 111; p 〈 0.0001), demonstrating that the expression of this enzyme is mainly under pretranslational control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02424572
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  • 8
    Electronic Resource
    Electronic Resource
    Comparative study of the expression of Rb and p53 genes in human colorectal cancers, colon carcinoma cell lines and synchronized human fibroblasts (1991)
    Springer
    Molecular and cellular biochemistry 107 (1991), S. 55-63 
    Details
    ISSN: 1573-4919
    Keywords: Rb and p53 genes ; gene expression ; colorectal cancers ; colon carcinoma cell lines ; cell cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract We have compared the expression of the retinoblastoma (Rb) and p53 genes in normal human fibroblasts, colon carcinoma cell lines, matched pairs of colorectal tumor tissues and adjacent normal mucosa and in synchronized human diploid fibroblast cell line W138. The increased expression of Rb and p53 RNA was observed in a majority of colorectal cancers in comparison to adjacent normal mucosa and is accompanied by proportional increase in the expression of histone H3 gene. The Rb and p53 RNA levels varied significantly between the various colon carcinoma cell lines. However, we found that the expression of Rb and p53 RNA is regulated differently in cell cycle synchronized normal human fibroblasts. The Rb mRNA level did not change with the position in the cell cycle and did not differ significantly whether the cells were serum deprived or in 10% serum. But p53 mRNA expression follows the same pattern as histone H3 mRNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02424576
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of dexamethasone and cycloheximide on the expression of amplified EGF-receptor gene in human A431 carcinoma cell line (1991)
    Springer
    Molecular and cellular biochemistry 103 (1991), S. 149-154 
    Details
    ISSN: 1573-4919
    Keywords: EGF-receptor gene ; gene expression ; cycloheximide ; dexamethasone and A431 carcinoma cell line
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Human A431 carcinoma cell line is known to have 30 fold amplified epidermal growth factor receptor (EGF-R) gene. We have studied the effect of steroid hormone dexamethasone (DEX) and protein synthesis inhibitor cycloheximide (CHX) on the expression of EGF-R gene in this cell line. DEX treatment and protein synthesis inhibition by CHX treatment cause a rapid 3 to 4 fold increase in the level of EGF-R mRNA and combined treatment of the above two agents have less than additive effect. It appears that mRNA for EGF-R accumulate within the cell during protein synthesis inhibition and upon removal of CHX, gets translated into EGF-R specific protein as judged by immuno-dot assay. We did not observe the phenomenon of ‘super induction’ nor much of an additive effect under condition of combined DEX and CHX treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227481
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  • 10
    Electronic Resource
    Electronic Resource
    Adrenergic hormones and control of cardiac myocyte growth (1991)
    Springer
    Molecular and cellular biochemistry 104 (1991), S. 35-43 
    Details
    ISSN: 1573-4919
    Keywords: α1-adrenergic receptors ; β-adrenergic receptors ; cardiac muscle ; cell culture ; gene expression ; protein kinase C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The molecular mechanisms of cardiac myocyte growth are relevant to important problems in cardiovascular disease. A cell culture model has been developed to explore the role of adrenergic hormones in cardiac myocyte growth and gene expression. Activation of a cardiac myocyte α1-adrenergic receptor by catecholamines induces hypertrophic growth of neonatal rat cardiac myocytes and initiates selective increases in contractile protein gene transcription. These effects on growth and gene expression do not depend on contractile activity. The cardiac myocytes contain at least two subtypes of α1-adrenergic receptors and at least three isoforms of protein kinase C (PKC). A distinct α1 receptor subtype may mediate hypertrophy and gene transcription. Different isoforms of PKC are translocated to different intracellular sites on activation, and there is evidence that the β-PKC isoform may be an element in the signal transduction pathway from an α1 receptor at the surface to the cardiac myocyte nucleus. Growth regulation through a β-adrenergic receptor can also be demonstrated in the culture model. The growth response mediated through a β-adrenergic receptor differs in several respects from that transduced through an al adrenergic receptor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229801
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  • 11
    Electronic Resource
    Electronic Resource
    Differential expression of insulin-like growth factor-I and insulin-like growth factor binding protein-1 in the diabetic rat (1991)
    Springer
    Molecular and cellular biochemistry 103 (1991), S. 41-50 
    Details
    ISSN: 1573-4919
    Keywords: insulin-like growth factor-1 ; binding proteins ; diabetes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Multiple factors contribute to the growth retardation which is a characteristic feature of uncontrolled diabetes. In this report we have examined the effects of streptozotocin-induced (STZ) diabetes on expression of insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-1 (IGFBP-1) in various tissues. As early as 7 days after STZ administration there was a modest reduction in IGF-I mRNA abundance. The reduction (10–30%) was of similar magnitude in each of the 7 tissues examined; liver, kidney, lung, diaphragm, quadraceps, heart and adipose tissue. However, the reduction achieved statistical significance only in the lung (p 〈 0.05) and diaphragm (p 〈 0.01). A further reduction in IGF-I mRNA abundance was seen in many tissues, 32 and 91 days after STZ administration. In contrast to the decrease in IGF-I mRNA, IGFBP-1 mRNA was significantly increased in the liver and kidney of diabetic rats. IGFBP-1 mRNA was detectable at only very low levels in other tissues but was increased in diabetic rats compared non-diabetic rats. In diabetic rats, a highly significant correlation (R = 0.75, p 〈 0.001) between hepatic IGFBP-1 mRNA and glucose was observed whereas there was no significant correlation between serum glucose and hepatic IGF-I mRNA abundance (R = 0.24, p = NS). Treatment of diabetic rats with insulin resulted in a small, non significant increase in hepatic and renal IGF-I mRNA and a significant decrease in renal IGFBP-1 mRNA abundance. The observations reported here are consistent with the hypothesis that diminished IGF-I expression and inhibition of available IGF-1 by increased levels of IGFBP-1 may explain the impaired growth seen in diabetic animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229592
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  • 12
    Electronic Resource
    Electronic Resource
    Blue light is required for survival of the tomato phytochrome-deficient aurea mutant and the expression of four nuclear genes coding for plastidic proteins (1991)
    Springer
    Plant molecular biology 16 (1991), S. 293-299 
    Details
    ISSN: 1573-5028
    Keywords: blue light ; phytochrome ; gene expression ; signal transduction chain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When dark-grown aurea mutant tomato seedlings which lack more than 95% of the phytochrome present in isogenic wild-type seedlings are kept in white or blue light, four nuclear-encoded transcripts coding for plastidic proteins (the light-harvesting chlorophyll a/b-binding protein of photosystem I and II [cab-PSII], plastocyanin and subunit 2 of photosystem I) are present in comparable amounts. These transcript levels in red light are strongly reduced in aurea seedlings when compared with those of wild type. Thus, blue light is required for normal expression of these genes in the mutant, while red light alone is not sufficient. Red light-grown aurea seedlings are very sensitive to blue light, even 10 minutes of blue light every day suffices to cause a measurable increase in cab-PSII transcript level. The action of blue light on the expression of cab-PSII in the mutant is under phytochrome control. After 8 days of blue light, phytochrome is almost as effective in inducing cab-PSII mRNA as in the isogenic wild type, whereas after 8 days of red light, only a small phytochrome response was observed in the mutant. It is concluded that blue light sensitizes the mutant to the residual phytochrome which allows normal gene expression and survival of the mutant under daylight conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020560
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  • 13
    Electronic Resource
    Electronic Resource
    Limited expression of a diverged β-tubulin gene during soybean (Glycine max [L.] Merr.) development (1991)
    Springer
    Plant molecular biology 16 (1991), S. 225-234 
    Details
    ISSN: 1573-5028
    Keywords: β-tubulin ; gene expression ; developmental regulation ; light regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined the developmental expression of a diverged soybean β-tubulin gene (designated sb-1), which had been cloned and sequenced previously. A probe specific for the sb-1 gene was constructed from the 3′ transcribed untranslated sequence. As a control, a more general probe for β-tubulin genes and their transcripts was constructed from a highly conserved region of the third exon of another soybean β-tubulin gene, sb-2. Poly(A)+ RNA, extracted from various soybean tissues and organs, was probed alternatively with the sb-1 gene-specific probe and with the generic β-tubulin probe. Levels of β-tubulin transcripts recognized by the generic probe differed by a factor of approximately 3 in the different tissues and organs and varied with the state of organ development. Highest levels were found in young, unexpanded leaves and they decreased as leaf maturation occurred. In contrast, transcripts of sb-1 were nearly undetectable in young leaves, and they increased as leaf maturation occurred. Levels of sb-1 transcript were low in all organs of the light-grown plant examined, except the hypocotyl, where they were approximately 10-fold higher. However, the highest levels of sb-1 transcripts were observed in elongating hypocotyls of etiolated seedlings. Exposure of six-day-old etiolated seedlings to light for 12 hours halted further hypocotyl elongation and brought about a dramatic, nearly 100-fold, decrease in the steady-state level of sb-1 transcripts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020554
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  • 14
    Electronic Resource
    Electronic Resource
    Isolation and analysis of cDNA encoding the 33 kDa precursor protein of the oxygen-evolving complex of potato (1991)
    Springer
    Plant molecular biology 17 (1991), S. 157-160 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; photosystem II ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00036821
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  • 15
    Electronic Resource
    Electronic Resource
    Stress responses in alfalfa (Medicago sativa L.) 12. Sequence analysis of phenylalanine ammonia-lyase (PAL) cDNA clones and appearance of PAL transcripts in elicitor-treated cell cultures and developing plants (1991)
    Springer
    Plant molecular biology 17 (1991), S. 415-429 
    Details
    ISSN: 1573-5028
    Keywords: L-phenylalanine ammonia-lyase mRNA ; fungal elicitor ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An expression library containing cDNAs derived from transcripts from fungal elicitor-treated alfalfa cell suspension cultures was screened with an antiserum raised against phenylalanine ammonia-lyase (PAL) from alfalfa. A single immunoreactive clone was isolated which encoded a full-length PAL cDNA (APAL1) consisting of a 2175 bp open reading frame, 96 bp 5′-untranslated leader and 128 bp 3′-noncoding region. The deduced amino acid sequence was 86.5% similar to that of the PAL2 gene of bean, and encoded a polypeptide ofM r 78865. A second PAL cDNA species was isolated, whose 3′-untranslated region was 86% identical to that of APAL1. Southern blot analysis indicated that PAL is encoded by a small multigene family in alfalfa. PAL transcript levels were rapidly and massively induced, and preceded increased PAL extractable activity, on exposure of alfalfa suspension cells to elicitor from baker's yeast. PAL transcripts were most abundant in roots, stems and petioles during growth and development of alfalfa seedlings. These studies provide the basis for an examination of the developmental and environmental control of a key enzyme of phenylpropanoid synthesis in a plant species which is readily amenable to stable genetic transformation.
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    URL: http://dx.doi.org/10.1007/BF00040636
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  • 16
    Electronic Resource
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    Regulation of Agrobacterium tumefaciens T-cyt gene expression in leaves of transgenic potato (Solanum tuberosum L. cv. Désirée) is strongly influenced by plant culture conditions (1991)
    Springer
    Plant molecular biology 17 (1991), S. 711-725 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium tumefaciens ; crown gall ; gene expression ; genomic position effects ; Solanum tuberosum L. ; T-cyt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The promoter region of the Agrobacterium tumefaciens T-cyt gene was linked in a translational fusion to the coding DNA of the reporter gene uidA (for β-glucuronidase or GUS protein; EC 3.2.1.31) and to nos 3′ flanking DNA. The chimaeric gene was introduced by Agrobacterium transformation into potato (Solanum tuberosum L. cv. Désirée). In nine transgenic lines, the average GUS levels were highest in extracts from stems and roots of in vitro grown plants (ca. 11 000 GUS activity units per pmol MU per mg protein per min) but lower in leaves of the in vitro grown plants (ca. 7000 units). GUS activity was intermediate in stems and roots of plants grown in soil as well as in in vitro crown galls (ca. 3000 units). Activity was low in tubers, irrespective of whether these developed in vitro or in soil (both ca. 100 units), and lowest of all in leaves of soil-grown plants (ca. 10–15 units). However, in shoot cultures reestablished from soil-grown plants, GUS activity in the leaves increased to that determined in the original shoot cultures. Hence, plant culture conditions strongly influenced the expression of the T-cyt-uidA-nos gene. In particular, it was silenced in leaves of soil-grown plants. The results are compared with previous analyses of the promoter region of the wild-type T-cyt gene and with the growth properties of a large number of crown gall cell lines and crown-gall-derived plants, including over forty S. tuberosum cv. Désirée cell lines isolated in the present study that were transformed with the wild-type T-cyt gene and six promoter-mutated derivatives. A number of implications are discussed for crown gall formation and for control of expression of plant genes which contain Activator or G-box type 5′ expression control sequences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037056
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  • 17
    Electronic Resource
    Electronic Resource
    Expression of photosynthesis genes in the cyanobacteriumSynechocystis sp. PCC 6803:psaA-psaB andpsbA transcripts accumulate in dark-grown cells (1991)
    Springer
    Plant molecular biology 17 (1991), S. 959-971 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; heterotrophic growth ; leucine zipper ; photosystem I ; photosystem II
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have cloned and sequenced thepsaA andpsaB genes from the unicellular cyanobacteriumSynechocystis sp. PCC 6803. These genes are arranged in tandem, are co-transcribed, and are highly homologous to thepsaA andpsaB genes previously characterized. RNA was isolated from light-grown cells, from cells put in total darkness with and without glucose, and from cells grown under light-activated heterotrophic growth (LAHG) conditions. Quantitation of hybridization to northern blots revealed only a slight decrease in the accumulation of thepsaA-psaB transcript in cells grown in complete darkness with glucose and in LAHG cells, relative to light-grown cells. Accumulation of thepsbA transcript steadily declines through dark incubation, with a steady-state level in LAHG cells 28% of that in light-grown cells. Transcripts frompsbD, psaD, andrbcLS accumulate in cells grown in complete darkness and in LAHG cells to approximately the same levels as in light-grown cells. Photosynthesis gene transcripts in cells grown in the dark without glucose were detected, but were highly degraded. Our data prove that transcripts from photosynthesis genes do accumulate in dark-grownSynechocystis 6803, which may allow for synthesis and assembly of photosystem (PS) I and PS II in the dark.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037136
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  • 18
    Electronic Resource
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    Water deficit modulates gene expression in growing zones of soybean seedlings. Analysis of differentially expressed cDNAs, a new β-tubulin gene, and expression of genes encoding cell wall proteins (1991)
    Springer
    Plant molecular biology 17 (1991), S. 591-608 
    Details
    ISSN: 1573-5028
    Keywords: hormones ; gene expression ; soybean ; water deficit ; tubulin ; cell wall proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transfer of soybean seedlings to low-water-potential vermiculite (ψw = −0.3 MPa) results in a reversible decrease in hypocotyl growth and modulation of several polysomal mRNAs (Plant Physiol 92: 205–214). We report here the isolation of two cDNA clones (pGE16 and pGE95) which correspond to genes whose mRNA levels are increased, and one cDNA clone (pGE23) which corresponds to a gene whose mRNA level is decreased in the hypocotyl zone of cell elongation by water deficit. In well-watered seedlings mRNAs hybridizing to pGE16 and pGE95 are most abundant in mature regions of the seedling, but in water-deficient seedlings mRNA levels are reduced in mature regions and enhanced in elongating regions. RNA corresponding to soybean proline-rich protein 1 (sbPRP1) shows a similar tissue distribution and response to water deficit. In contrast, in well-watered seedlings, the gene corresponding to pGE23 was highly expressed in the hypocotyl and root growing zones. Transfer of seedlings to low-water-potential vermiculite caused a rapid decrease in mRNA hybridizing to pGE23. Sequence analysis revealted that pGE23 has high homology with β-tubulin. Water deficit also reduced the level of mRNA hybridizing to JCW1, an auxin-modulated gene, although with different kinetics. Furthermore, mRNA encoding actin, glycine-rich proteins (GRPs), and hydroxyproline-rich glycoproteins (HRGPs) were down-regulated in the hypocotyl zone of elongation of seedlings exposed to water deficit. No effect of water deficit was observed on the expression of chalcone synthase. Decreased expression of β-tubulin, actin, JCW1, HRGP and GRP and increased expression of sbPRP1, pGE95 and pGE16 in the hypocotyl zone of cell elongation could participate in the reversible growth inhibition observed in water-deficient soybean seedlings.
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    URL: http://dx.doi.org/10.1007/BF00037046
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    A novel proline-rich protein from wheat (1991)
    Springer
    Plant molecular biology 16 (1991), S. 663-670 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; proline-rich protein ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA (WPRP1) encoding a wheat proline-rich protein has been isolated and sequenced. The amino acid composition shows 45% proline, with high levels of methionine, lysine and glutamic acid. The derived 378 residue amino acid sequence has a highly repetitive structure which is unlike those of other proline-rich proteins. The WPRP1 cDNA clone was used to determine the copy number and chromosomal location of the WPRP1 gene by restriction fragment length polymorphism analysis of wheat inbred lines. Although WPRP1 is encoded by a single-copy gene it is also a representative of a larger family of related sequences. RNA gel blot analysis showed that expression of WPRP1 is highest in rapidly growing tissue which together with its amino acid composition suggests a structural role for the encoded protein.
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    URL: http://dx.doi.org/10.1007/BF00023430
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    Expression of inducible angiosperm promoters in a gymnosperm,Picea glauca (white spruce) (1991)
    Springer
    Plant molecular biology 17 (1991), S. 19-27 
    Details
    ISSN: 1573-5028
    Keywords: conifer ; gene expression ; heterologous promoters ; inducible promoter activity ; particle acceleration ; transient assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electrical discharge particle acceleration was used to test the transient expression of numerous inducible angiosperm promoters in a gymnospermPicea glauca (white spruce). Promoter expression was assayed in three different tissues capable ofin vitro regeneration, zygotic embryos, seedlings and embryogenic callus. The promoters tested include the light-inducibleArabidopsis and soybean ribulose-1,5-bisphosphate small subunit promoters and a maize phosphoenolpyruvate carboxylase promoter; a soybean heat-shock-inducible promoter, a soybean auxin inducible promoter and a maize alcohol dehydrogenase promoter. Promoters were cloned into a promoter-less expression vector to form a promoter-β-glucuronidase-nopaline synthase 3′ fusion. A similar construct was made using the cauliflower mosaic virus 35S (CaMV 35S) promoter as a control. All promoters were expressed in white spruce embryos, yet at levels lower than CaMV 35S. In addition, in the embryos the heat-shock and the alcohol dehydrogenase promoters showed inducible expression when given the proper induction stimulus. In seedlings, expression of all promoters was lower than in the embryos and expression was only inducible with the heat-shock promoter in the cotyledons. Of the tissues tested, the expression level of all promoters was lowest in embryogenic callus. Interestingly, the expression of the β-glucuronidase gene in embryogenic callus was restricted to the proembryonal head cells regardless of the promoter used. These results clearly demonstrate the use of particle bombardment to test the transient expression of heterologous promoters in organized tissue and the expression of angiosperm promoters in a gymnosperm.
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    URL: http://dx.doi.org/10.1007/BF00036802
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    An ethylene-responsive flower senescence-related gene from carnation encodes a protein homologous to glutathione s-transferases (1991)
    Springer
    Plant molecular biology 17 (1991), S. 277-281 
    Details
    ISSN: 1573-5028
    Keywords: carnation ; Dianthus caryophyllus ; ethylene ; gene expression ; glutathione s-transferase ; senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carnation flower petal senescence is associated with the expression of specific senescence-related mRNAs, several of which were previously cloned [5]. The cDNA clone pSR8 represents a transcript which accumulates specifically in senescing flower petals in response to ethylene. Here we report the structural characterization of this cDNA. A second cDNA clone was isolated based on shared sequence homology with pSR8. This clone, pSR8.4, exhibited an overlapping restriction endonuclease map with pSR8 and contained an additional 300 nucleotides. Primer extension analysis revealed the combined cDNAs to be near full-length and the transcript to accumulate in senescing petals. Analysis of the nucleotide sequence of SR8 cDNAs revealed an open reading frame of 220 amino acids sufficient to encode a 25 kDa polypeptide. Comparison of the deduced polypeptide sequence of pSR8 with other peptide sequences revealed significant similarity with glutathione s-transferases from a variety of organisms. The predicted polypeptide sequence shared 44%, 53% and 52% homology with GSTs from maize, Drosophila and man, respectively. We discuss our results in relation to the biochemistry of flower petal senescence and the possible role of glutathione s-transferase in this developmental process.
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    URL: http://dx.doi.org/10.1007/BF00039505
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    Wound-regulated accumulation of specific transcripts in tomato fruit: interactions with fruit development, ethylene and light (1991)
    Springer
    Plant molecular biology 17 (1991), S. 453-464 
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    ISSN: 1573-5028
    Keywords: ethylene ; fruit repening ; gene expression ; light ; Lycopersicon ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regulation of three cDNA clones (pT52, pT53, and pT58) was analyzed in terms of wounding alone and wounding in conjunction with developmental and environmental cues (ripening, ethylene, and light) in tomato fruit tissue. The pT52-specific transcript level is induced by wounding in early-red and red stage fruit and by ethylene. The pT58-specific transcript level is also induced by wounding and ethylene in early-red stage fruit but is not induced by wounding in red fruit. The pT53-specific transcript level is repressed by wounding in early-red and red stage fruit. Like the pT52- and pT58-specific transcripts, the pT53-specific transcript is induced by ethylene. Furthermore, the level of the pT52-specific transcript is regulated by light. Analysis of unwounded tissue showed that the abundance of each cdNA-specific transcript changes during fruit ripening and that each of the transcripts is present in other plant organs as well. This analysis provides information about the interactions between developmental and environmental factors affecting these genes.
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    URL: http://dx.doi.org/10.1007/BF00040639
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    Expression of a bacterial lysine decarboxylase gene and transport of the protein into chloroplasts of transgenic tobacco (1991)
    Springer
    Plant molecular biology 17 (1991), S. 475-486 
    Details
    ISSN: 1573-5028
    Keywords: Nicotiana tabacum ; plant transformation ; gene expression ; bacterial lysine decarboxylase ; protein transport ; chloroplasts ; cadaverine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A possible approach for altering alkaloid biosynthesis in plants is the expression of genes encoding key enzymes of a pathway such as lysine decarboxylase (ldc) in transgenic plants. Two strategies were followed here: one focused on expression of the gene in the cytoplasm, the other on subsequent targeting of the protein to the chloroplasts. Theldcgene fromHafnia alvei was therefore (a) placed under the control of the 1′ promoter of the bidirectional Tr promoter fromAgrobacterium tumefaciens Ti- plasmid, and (b) cloned behind therbcS promoter from potato fused to the coding region of therbcS transit peptide. Bothldc constructs, introduced intoNicotiana tabacum with the aid ofA. tumefaciens, were integrated into the plant genome and transcribed as shown by Southern and northern hybridization. However, LDC activity was only detectable in plants expressing mRNA under the control of therbcS promoter directing the LDC fusion protein into chloroplasts with the aid of the transit peptide domain. In plants expressing the processed bacterial enzyme cadaverine levels increased from nearly zero to 0.3–1% of dry mass.
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    URL: http://dx.doi.org/10.1007/BF00040641
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    Structure, expression, chromosomal location and product of the gene encoding ADH1 inPetunia (1991)
    Springer
    Plant molecular biology 17 (1991), S. 37-48 
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    ISSN: 1573-5028
    Keywords: alcohol dehydrogenase ; anaerobiosis ; chromosome mapping ; gene expression ; Petunia hybrida ; plant development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genomic clone for an alcohol dehydrogenase (Adh) gene has been isolated fromPetunia hybrida cv. V30 by screening aPetunia genomic library with a maizeAdh1 probe. A combination of RFLP and allozyme segregation data failed to demonstrate which of twoAdh loci, both of which map to chromosome 4, was the source of the cloned gene. The product of the cloned genes has been identified unequivocally by a transient expression assay inPetunia protoplasts. We have designated this genePetunia Adh1. The expression of this gene is tightly regulated in the developing anther, where its gene product is the predominant ADH isozyme. It is anaerobically inducible in roots, stems and leaves of seedlings. The induction of enzyme activity is correlated with induction ofAdh1 mRNA.
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    URL: http://dx.doi.org/10.1007/BF00036804
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    Expression and stability of amplified genes encoding 5-enolpyruvylshikimate-3-phosphate synthase in glyphosate-tolerant tobacco cells (1991)
    Springer
    Plant molecular biology 17 (1991), S. 1127-1138 
    Details
    ISSN: 1573-5028
    Keywords: tobacco ; 5-enolpyruvylshikimate-3-phosphate synthase ; cDNA clone ; gene expression ; gene amplification ; glyphosate ; cell culture ; tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two distinct cDNAs for 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) were obtained from a glyphosate-tolerant tobacco cell line. The cDNAs were 89% identical and the predicted sequences of the mature proteins were greater than 83% identical with EPSPS proteins from other plants. Tobacco EPSPS proteins were more similar to those from tomato and petunia than Arabidopsis. One cDNA clone, EPSPS-1, represented a gene that was amplified in glyphosate-tolerant cells, while the gene for EPSPS-2 was unaltered in these cells. Consequently, EPSPS-1 mRNA was more abundant in tolerant than unselected cells, whereas EPSPS-2 mRNA was at relatively constant levels in these cell lines. Exposure of unselected cells and tobacco leaves to glyphosate produced a transient increase in EPSPS mRNA. However, glyphosate-tolerant cells containing amplified copies of EPSPS genes did not show a similar response following exposure to glyphosate. A significant proportion of the EPSPS gene amplification was maintained when tolerant cells were grown in the absence of glyphosate for eight months. Plants regenerated from these cells also contained amplified EPSPS genes.
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    Retention characteristics of chlorinated polycyclic aromatic hydrocarbons in normal phase HPLC. I. Chloro-added PAHs (1991)
    Springer
    Chromatographia 32 (1991), S. 334-340 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Normal phase separations ; Cyanopropyldimethyl silica ; Chloro-added polycyclic aromatic hydrocarbons ; Environmental samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention characteristics in normal phase HPLC of highly biologically active chloro-added polycyclic aromatic hydrocarbons (PAHs) were studied. Silica, cyanopropyldimethylsilyl- and aminopropylsilyl- modified stationary phases were investigated. Retention properties of chloroadded PAHs on these phases were shown to be strongly influenced by the number of chloro-additions. This is due to the strong polarity of the methylene carbon at the chloro-addition site. Active silica had a strongly degrading effect on the unstable chloro-added PAHs during separation. Aminopropylsilica did not exhibit sufficient selectivity towards chloro-added PAHs when compared to chlorosubstituted PAHs. Cyanopropyldimethylsilica was shown to be applicable to a group separation of chloro-added and chloro-substituted PAHs. A fast clean-up procedure for chloro-added PAHs in complex samplesis outlined. It involves an initial elimination of more polar substances on a short open column with strongly deactivated silica and a subsequent separation on a cyanopropyldimethylsilyl HPLC column in normal phase mode.
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    Chromatography in pore networks II — The role of structure and adsorption in the band broadening (1991)
    Springer
    Chromatographia 32 (1991), S. 345-349 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column packings ; Pore size distribution ; Diffusion and adsorption ; Band broadening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The complex intraparticle structure typical of chromatographic column packings has been analyzed by use of an equivalent network model which emphasizes pore size distribution and connectivity. Special attention is given as to the way in which diffusion and adsorption interact and display modified peak spreading characteristics according to the morphology of the pore space. This study reveals a very significant increase in the column band broadening over that expected from physical adsorption which can arise from particular distributions of pore sizes. This has implications for designing packings which take advantage of the separating power due to adsorption but do not compromise the resolution of the chromatographic system.
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    Multiple forms of DNA-methylases from hepatic nuclei of animals in health and disease (1991)
    Springer
    Bulletin of experimental biology and medicine 111 (1991), S. 47-50 
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    ISSN: 1573-8221
    Keywords: DNA-methylase ; multiple forms ; hydrophobic properties ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1007/BF00841238
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    Regulation of proenkephalin A gene expression in aggregating fetal rat brain cells (1991)
    Springer
    Cellular and molecular neurobiology 11 (1991), S. 245-251 
    Details
    ISSN: 1573-6830
    Keywords: enkephalin ; mRNA ; depolarization ; gene expression ; aggregating cells ; neuronal cell culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Aggregating fetal rat brain cells express a significant amount of proenkephalin A (PENK) mRNA, and a selective radioimmunoassay shows that this mRNA is also translated into enkephalins. 2. Depolarization with potassium chloride (KC1) or veratridine increases the expression of PENK mRNA in a time-dependent fashion, with a maximal increase of sixfold. It is interesting, however, that depolarization of the same cultures with KC1 has no effect on the expression of prodynorphin mRNA. 3. An increase in PENK mRNA levels has been also observed in cultures treated with 8-Br-cAMP, phorbol 12-myristate-13-acetate (TPA), or dexamethasone. 4. However, incubation of the cultures with the opioid agonist etorphine or the antagonist naltrexone did not alter PENK gene expression, suggesting that there is not feedback control of opioids on PENK biosynthesis in these cells. 5. The increase in PENK mRNA in depolarized and in TPA-, dexamethasone-, or 8-Br-cAMP-treated cultures was not accompanied by a significant increase in the amount of free immunoreactive met-enkephalin. Fetal brain cell cultures are therefore a useful neuronal model system for studying the mechanism that regulated the expression of PENK mRNA.
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    Separation and characterization of a viscosity index improver copolymer by high-performance liquid chromatography (1991)
    Springer
    Chromatographia 31 (1991), S. 71-74 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size exclusion chromatography ; Styrene-methacrylate polymers ; IR and UV spectroscopy ; Lubricating oils additives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Characterization of a poly(styrene-alkyl methacrylate) viscosity index improver according to its chemical composition distribution and molecular weight distribution was carried out by liquid adsorption chromatography, size exclusion chromatography and infrared and ultraviolet spectrophotometry. The industrial polymer was fractionated by liquid chromatography using silica gel as adsorbent and a mixture of 1,2-dichloroethane and methanol as mobile phase. Each fraction was analyzed by size exclusion chromatography and infrared and ultraviolet spectroscopy. The number average molecular weight ranged from 10000 to 36000 and the weight average molecular weight from 19000 to 264000. The styrene content of the various fractions analysed was between 29.5% and 72.2%.
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    Determination of laidlomycin and 26-deoxylaidlomycin by high-performance liquid chromatography (1991)
    Springer
    Chromatographia 31 (1991), S. 603-605 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Laidlomycin, 26-deoxylaidlomycin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High performance liquid chromatography on an octadecyl silica column has been used to determine laidlomycin: 26-deoxylaidlomycin ratios and to determine the concentration of both compounds by standard addition in samples prepared from fermentation broths ofStreptoverticillium olivoreticuli. A refractive index detector was preferred to an ultraviolet detector owing to the presence of UV-absorbing impurities which could not be completely separated from the substances of interest. Linear relationships were obtained from the calibration data. The coefficient of variation for the estimation of ratio and concentration of the compounds determined was better then 5%. The estimated limit of detection for both substances was about 50μg·ml−1.
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    Prediction of retention of O-ethyl, O-aryl and N-isopropyl phosphoroamidothioates in RP-HPLC from molecular structure parameters (1991)
    Springer
    Chromatographia 31 (1991), S. 143-146 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Molecular structure parameters ; Prediction of retention ; Phosphoroamidothiotes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Multi-variable regression analysis between lnkw, c (in retention equation lnk′=lnkw+cCb) and molecular structure parameters, including hydrophobicity, electric effect, field effect and position-specific effect constant, was carried out with O-ethyl, O-aryl and N-isopropyl phosphoroamidothioates as test solutes. With these quantitative relationships, the retention behaviour of these solutes for different mobile phase compositions was predicted. The results showed that there are only 26.7% of total, experimentally measured, capacity factors with relative deviations larger than 5% and only 2.2% with deviations larger than 10%, which means that it is possible to apply the method reported to predict retention values for qualitative purposes for different mobile phase compositions.
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    A method for the determination of histamine in wine by HPLC with precolumn derivatization with phenylisothiocyanate (1991)
    Springer
    Chromatographia 31 (1991), S. 133-136 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Histamine in wine ; Pre-column derivatization ; Solid phase extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for determining histamine in wine by precolumn derivatization with PITC (phenylisothiocyanate) with reversed-phase HPLC and UV detection is reported. Histamine can be determined together with the 24 amino acids within 40 min, or separately in a shorter time (less than 4 min) if a prior solid phase extraction clean-up is used.
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    Retention behavior of the inclusion complexes of some polycyclic aromatic hydrocarbons with β-cyclodextrin (1991)
    Springer
    Chromatographia 31 (1991), S. 157-162 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cyclodextrin inclusion complexes ; Structure-retention relationships ; Polycyclic aromatics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behaviour of a group of polycyclic aromatic hydrocarbons having nearly equal ionization potentials but different molecular polarizability values was investigated by reversed-phase HPLC and gas chromatography, using β-cyclodextrin as a selective inclusion reagent. In HPLC, the cyclodextrin was applied as an additive to the ethanolwater binary mobile phase, while in gas chromatography β-cyclodextrin served as the stationary phase coated on an inert support. The relationships between the capacity factors, molecular polarizabilities and the shape parameter of solute molecules is discussed.
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    Quantitation of cortico-steroids as common adulterants in local drugs by HPLC (1991)
    Springer
    Chromatographia 31 (1991), S. 67-70 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cortico-steroids ; Drug adulterants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive and specific method for quantitation of the steroids betamethasone, prednisolone and cortisone acetate commonly used as adulterants in locally produced herb extracts and in certain homeopathic drugs is described. Reverse-phase liquid chromatography with UV detection has been used.
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    Chromatography of inorganic anions on poly(vinyl alcohol) gel columns with acidic eluents (1991)
    Springer
    Chromatographia 31 (1991), S. 80-84 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Poly(vinyl alcohol) gel ; Inorganic anions ; UV detection for IC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Poly(vinyl alcohol) (PVA) gel shows ionic retention properties for common inorganic anions when an acidic eluent is used. The ionic property of the PVA gel is due to the proton-acceptable nitrogen atoms of the cross-linking agent and the carboxylic residues being comprised in the gel matrix. The extent of the net charge on the gel surface depends on the pH of the eluent. At a pH ranging from 2.3 to 5.3, the PVA gel behaves as a weak anion exchanger with very low ion-exchange capacity. At these conditions four UV-absorbing inorganic anions (bromate, bromide, nitrate, and nitrite) are separated by eluting with aqueous sulfuric acid. Alkyl groups introduced on the gel surface hinder the ionized solute molecules from accessing to the positively charged functional groups on the gel surface. A neutral solute (HNO2) is retained with non-ionic interactions.
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    Influence of injection conditions in reversed-phase high-performance liquid chromatography of chlorophylls and carotenoids (1991)
    Springer
    Chromatographia 31 (1991), S. 589-594 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Injection conditions ; Chlorophylls and carotenoids ; Extraction solvents ; Phytoplankton pigments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The RP-HPLC analysis of chlorophylls, their degradation products (chloropigments) and carotenoids is very sensitive to the nature of the injection solvent. The effect of sample-solvent interaction can result in the production of distorted, or even false, peaks that could be erroneously interpreted as “pigment like” or as poor chromatographic resolution. The previously suggested theoretical explantion, based on differences in solvent characteristics as expressed by the Polarity Index (P′) or even by the more precise solvent strength parameter for reversed-phase systems (S) we use, was unsatisfactory. The problem seems more complex, with other parameters such as injection volume and solute concentration or solvent selectivity also playing a role. As a practical consequence, however, suggesions are made for optimum injection conditions. Also, the presence of ion-pairing reagents in the injection solvent is demonstrated to be unnecessary.
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    The influence of end-capping on the enantioselectivity of a chiral phase (1991)
    Springer
    Chromatographia 31 (1991), S. 129-132 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; End-capping ; Chiral stationary phase ; Enantioselectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of end-capping chiral stationary phases (CSP's) derived fromN-(2-naphthyl)alanine undecyl ester has been examined using either trimethylchlorosilane (TMCS), hexamethyldisilazane (HMDS), or bis(trimethylsilyl) trifluoroacetamide (BSTFA) as end-capping reagents. The separation factor (α) and capacity factor (k′) of the enantiomers ofN-(3,5-dinitrobenzoyl)leucine octadecyl amide andN-(3,5-dinitrobenzoyl)alanine butyl ester were evaluated on three columns all packed with material from the same batch of stationary phase. These columns were essentially identical before, but not after end-capping with the above reagents. TMCS and HMDS were found to be superior to BSTFA, which appears to cause a significant loss of bonded phase from the silica surface. It seems that residual silanols affect the retention either by interacting with the analyte or by interacting with strands of stationary phase. End-capping usually increases enantioselectivity, sometimes by decreasing k′ for the first enantiomer and increasing k′ for the second enantiomer. The enhancement in enantioselectivity is greatest in relatively nonpolar mobile phases and occurs to a greater extent for phases having incomplete surface coverages.
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    Chromatographic characterization of a bonded liquid crystal stationary phase for HPLC (1991)
    Springer
    Chromatographia 31 (1991), S. 147-151 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Liquid crystal bonded phase ; Polycyclic aromatics ; Carvone and pulegone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A chromatographic and thermodynamic study of the compound [4-(allyloxy)benzoyl]-4-methoxyphenyl (ABMP) as a model of a chemically bonded liquid crystal stationary phase for HPLC was undertaken. A number of polycyclic aromatic hydrocarbons (PAHs) and two small solutes, carvone and pulegone, were studied under varying solvent and temperature conditions. Plots of log k′ vs. % organic in the mobile phase were not completely linear in all cases. The van't Hoff plots revealed at least one phase transition. The enthalpies of solute transfer from the mobile phase to the ABMP phase were determined for several PAHs. All tests indicate that ABMP possess liquid crystal properties when bonded to particulate silica.
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    Silica surface controversies, strong adsorption sites, their blockage and removal. Part II (1991)
    Springer
    Chromatographia 31 (1991), S. 193-205 
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    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Silanol adsorption centres ; Strongly interacting adsorption sites ; Suppression of adsorption activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this second part of the review heterogeneity of the silica surface is described and evidence is presented for the existence of a low population of strong adsorption sites. Methods of detection and determination of these strongly interacting sites are discussed. The last part of the review is devoted to the suppression of unwanted adsorption activity. Methods of blockage and special methods for the preparation of HPLC packings are described.
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    A rapid HPLC determination of narasin in fermentation broth (1991)
    Springer
    Chromatographia 31 (1991), S. 277-280 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Simplex optimization ; Narasin in fermentation broth ; Vanillin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid HPLC assay with post-column derivatization has been developed for the determination of narasin in fermentation broth. The reaction of narasin with substituted benzaldehydes was investigated under first order conditions and the rate constants were determined for a variety of substituted benzaldehydes. Vanillin reacted most rapidly to produce a red color. The reaction conditions were optimized to acheive a maximum response with a minimum analysis time.
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    The effects of pH and alcoholic organic modifiers on the direct separation of some acidic, basic and neutral compounds on a commercially available ovomucoid column (1991)
    Springer
    Chromatographia 31 (1991), S. 329-334 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ovomucoid stationary phase ; Chiral separations ; Mobile phase effects ; Protein conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effects of alcoholic modifiers and pH on the chromatographic properties of an immobilized ovomucoid chiral stationary phase have been investigated using acidic, basic and neutral solutes. A series of primary, secondary and tertiary alcohols and pH's ranging from 3.5 to 6.0 were used in this study. The results indicate that both the shape and the hydrophobicity of the alcoholic modifier affect retention (k') and enantioselectivity (α). In general, an increase in the hydrophobicity of the modifier results in a decrease in k's and α's. However, this is not the case whent-butanol is the modifier, suggesting that the size of the alkyl moiety attached to the carbinol carbon also contributes to the chromatographic results. The pH studies indicated that Coulombic interactions play a role in the retention of the acidic and basic solutes. The results also suggest that in addition to ethanol and 1-propanol,t-butanol should be considered during optimization and that maximum efficiencies may be obtained at pH 5.0.
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    Influence of the mobile phase composition on the adsorption isotherms of an amino-acid derivative on immobilized bovine serum albumin (1991)
    Springer
    Chromatographia 31 (1991), S. 323-328 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Adsorption isotherms ; Immobilized serum albumen ; Chiral stationary phase ; Leucine, N-benzoyl derivative
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The saturation capacity of columns packed with bovine serum albumin immobilized on silica has been determined for the N-benzoyl derivative of leucine at different compositions of a 1-propanol/water mobile phase. In all cases it has been found that the equilibrium adsorption data are well accounted for by a biLangmuir isotherm. The experimental data are consistent with the assumption that the column saturation capacity of the chiral selective sites as well as the saturation capacity of the non-selective sites are independent of the 1-propanol concentration in the range 0–10%.
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    New synthesis of alkyldihydrosilanes and their applications in modification of silica gel (1991)
    Springer
    Chromatographia 31 (1991), S. 335-341 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded phase synthesis ; Alkyl and aryldimethyl phases ; CP/MAS NMR spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A comparison of newly synthesized, reversed-phase bonded stationary phases is presented. The materials studied include monomeric n-octyl, n-octadecyl, aryl and n-octyldihydrogeno bonded-phases. Differences in reactivity of the silane functional groups are demonstrated and the high coverage obtained with the hydrogeno-bonded phases is shown. The structures of the bonded phases have been determined by29Si and13C CP/MAS NMR spectroscopy.
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    Comparison of surface states of chemically modified silicas in aqueous acetonitrile and methanol (1991)
    Springer
    Chromatographia 31 (1991), S. 347-350 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically modified silicas ; Surface states ; n-alkylbenzenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The thermodynamic behaviour of n-alkylbenzenes on chemically modified silicas in reversed-phase liquid chromatography has been examined in acetonitrile-water and methanol-water systems. Plots of the thermodynamic parameters obtained against the organic solvent compositions indicate an interesting trend which implies that the surface states of the chemically modified silicas under the two eluent systems are different.
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    A particle size distribution analysis of stressed HPLC column packing material (1991)
    Springer
    Chromatographia 31 (1991), S. 362-366 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Particle size distribution ; Stationary phase stress ; Silica gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A particle size distribution analysis has been completed on three different HPLC column packing materials including silica gel (Si60) and two bonded phases (RP8 and RP18). The stationary phases were subjected to 18 hours stress with 1 N or 3 N KOH and found to have quantitatively different distribution patterns initially, at 13 hours and finally at 18 hours although the average particle diameters for the Si60 and RP8 were the same or higher at 18 hours as initially. Thirteen hoursstress with sodium octanesulfonate, tetrabutylammonium phosphate and ammonium acetate at exaggerated conditions also resulted in distributional changes with the Si60 and RP8 decreasing in average particle diameter when exposed to ammonium acetate and tetrabutylammonium stressing respectively.
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    Separation of food-related biogenic amines by ion-interaction reversed-phase high performance liquid chromatography. Tyramine, histamine, 2-phenylethylamine, tryptamine and precursor aminoacids. Application to red wine (1991)
    Springer
    Chromatographia 31 (1991), S. 381-386 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Biogenic amines ; Wine ; Food-related biogenic amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Methods for the separation of food-related biogenic amines (histamine, tyramine, 2-phenylethylamine and tryptamine) have been developed based on ion-interaction reversed-phase liquid chromatography. Two different interaction reagents have been comparatively used, namely octylamine ortho-phosphate (at wave-lengths of 230, 254 and 280 nm) and octylamine salicylate (at a wavelength of 254 nm). The different elution sequence orders shown by the investigated amines for the two reagents are discussed and compared. The detection limits obtained were 20 ppb for tryptamine (λ =280 nm), 500 ppb for 2-phenylethylamine (λ=254 nm), 400 ppb for tyramine (λ=230 or 280 nm) and 900 ppb for histamine (λ=230 nm). The method was applied to the analysis of a five years old Italian red wine, in which 2-phenylethylamine (at a concentration of 72±3 ppm) and tryptamine (at a concentration of 4.0±0.3 ppm) were found to be present.
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    Estimation of the degree of self-association of water using a novel retention model (1991)
    Springer
    Chromatographia 31 (1991), S. 387-392 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention model ; Self-association of water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An attempt has been made to gain a semi-quantitative insight into the self-association of water molecules through hydrogen bonds. This was only possible with the use of a new solute retention model for the chromatographic systems by considering intermolecular interactions between the constituents of binary mobile phases. Four different sizes of the average associative aqueous multimer were assumed. By comparing measured and calculated retention values, the existence of associated aqueous multimers consisting of 100 aqueous monomer units is postulated as an average multimer structure.
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    Analysis of nucleotides, nucleosides, nucleobases in cells by ion-pair reversed-phase HPLC (1991)
    Springer
    Chromatographia 31 (1991), S. 401-410 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair reversed-phase separations ; Nucleotides ; Extraction from cells and tissue ; Retention mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC methods for the separation of nucleotides, nucleosides and nucleobases by ion-pair reversed-phase are reviewed. The advantages of these are discussed versus anion-exchange and reversed phase separations. Extraction procedures for nucleotide determinations from cells and tissues are pointed out in detail. Extracts from red blood cells, Ehrlich ascites tumour cells, hepatocytes, intestine are used for determination of nucleotide concentrations by the methods described.
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    Automated HPLC-amino acid determination of protein hydrolysates by precolumn derivatization with OPA and FMOC and comparison with classical ion exchange chromatography (1991)
    Springer
    Chromatographia 31 (1991), S. 441-447 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion exchange chromatography ; Quantitative amino acid analysis ; OPA/FMOC precolumn derivatization ; Cheese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An improved HPLC method for the quantitative determination of the amino acids from hydrolysed cheese proteins and peptides is described. Some important improvements to the existing method are suggested. The addition of piperidine-4-carboxylic acid (PICA) as a hydrolysis-resistant internal standard enabled the quantification of secondary amino acids. The following analytical parameters have been determined: repeatability, detection limit and linearity in the measuring range. A statistical comparison with the classical ion chromatographic method gave an excellent correlation for all determined amino acids. Both methods are free of artifacts and systematic errors. Compared with ion chromatography, HPLC shows the following advantages: faster equilibration of the column, shorter retention times, more stable baseline, narrower peaks and more sensitive fluorescence detection. A drawback is the slightly lower repeatability for some amino acids.
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    Chiral amino acid microanalysis by direct optical resolution of fluorescent derivatives on BSA-based (resolvosil) columns (1991)
    Springer
    Chromatographia 31 (1991), S. 429-433 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separations ; Amino acids ; Fluorogenic derivatization ; N-(Chloroformyl)-carbazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new reagent for fluorescence labelling of amino acids, N-(chloroformyl)-carbazole, has been used in order to achieve high sensitivity of detection as well as good optical resolution. The derivatization reaction is fast and conveniently carried out at room temperature by shaking a buffered aqueous solution of the amino acids with an acetone solution of the reagent. The individual derivatized amino acids are first separated and collected via chromatography on a standard octadecyl-silica column. Each amino acid derivative is then analyzed for enantiomer composition by re-injection on a BSA-silica (Resolvosil®) column using fluorescence detection. For some amino acids (alanine, threonine, phenylalanine, tryptophan) enantiomeric separation factors exceeding α=3 have been obtained. The phosphonic acid analogue of alanine (1-aminoethylphosphonic acid) was also found to be well resolved into its enantiomers.
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    Analysis of catechins and proanthocyanidins in grape seeds by HPLC with photodiode array detection (1991)
    Springer
    Chromatographia 31 (1991), S. 465-468 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Catechins ; Grape seeds ; Proanthocyanidins ; UV-visible spectroscopy/diode array detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase, high-performance liquid chromatography coupled to photodiode array detection has been used to analyse catechins and proanthocyanidins extracted from grape seeds. Results show that the ethyl acetate fraction obtained by passing extracts of samples adjusted to pH 7.0 through preconditioned C18 SEP-PAK cartridges contains several catechins and proanthocyanidins. Seven peaks have been assigned to standard catechins and proanthocyanidins on the basis of their retention times and UV spectra. Other peaks which appear in the chromatogram show spectral behaviour similar to that of standard catechins and proanthocyanidins.
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    HPLC of individual site glycoforms in serum orosomucoid (1991)
    Springer
    Chromatographia 31 (1991), S. 478-480 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Orosomucoid ; Complex glycans ; α1 glycoprotein ; Glycopeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The glycoforms contained within each glycosylation site of orosomucoid can be separated by reverse-phase HPLC without removal of the associated peptide or chemical derivatization. The chromatographic properties of the glycopeptides are dominated by the peptide portion but modified by the hydrophilicity of the glycan in a regular manner depending on its size. Assignments for known structures are readily made, permitting quantitative assessment of changes in glycoform concentration at individual glycosylation sites.
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    Immunoaffinity precolumn for selective sample pretreatment in column liquid chromatography: Immunoselective desorption (1991)
    Springer
    Chromatographia 31 (1991), S. 469-477 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Immunoaffinity precolomn ; Oestrogens ; Bioanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An automated liquid chromatographic system is described using immunoaffinity precolumns for sample pretreatment. The system consists of a column-switching unit allowing preconcentration from a large volume of sample (e.g. 15 ml of urine) onto an immunoaffinity precolumn (containing polyclonal antibodies immobilized on Sepharose). After sorption, the analytes are desorbed by a mixture of two cross-reacting solutes, followed by reconcentration on a C-18-bonded silica precolumn, and then separation on a C-18-bonded silica analytical column. Using oestrogen steroids as model compounds and UV absorbance detection, the minimum detectable concentration is ca. 200 ng/l with a repeatability of 6–8%. The total analysis time is 45 min which allows the unattended analysis of 30 samples per day. The features of the sample pretreatment method, especially of the immunoselective desorption, are evaluated and the general applicability of the system is discussed.
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    Chromatographic optimization for the determination of traces of selenonium and arsonium cations by HPLC with on-line detection by AAS (1991)
    Springer
    Chromatographia 31 (1991), S. 481-488 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Selenonium and arsonium cations ; AAS detection ; Chromatographic optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Optimal mobile phase compositions were determined for the separation of selenonium ions [trimethylselenonium, (2-hydroxyethyl)dimethylselenonium and (2-acetoxyethyl)dimethylselenonium] and, separately, for arsonium ions (tetramethylarsonium, arsenobetaine, and arsenocholine) by HPLC with detection by atomic absorption spectrometry (AAS). Surface response methodologies were used to predict the variations in detector response (peak area), capacity factors, and selectivities as a function of the mobile phase composition. For selenonium analytes, a mixture of triethylammonium and trimethylsulfonium ions in the methanol-1% acetic acid mobile phase provided a compromise between resolving power and chromatographic efficiency. By contrast, optimum chromatography of the arsonium analytes was obtained by replacing onium additives in the mobile phase by picrylsulfonic acid. For both selenonium and arsonium analytes, the dominant interaction with the stationary phase was with residual silanols and improvements to the chromatographic performance of these analytes resulted in appreciable decreases in their limits of detection.
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    Flame ionization detection for the determination of the chemical composition distribution of non-UV absorbing copolymers (1991)
    Springer
    Chromatographia 31 (1991), S. 493-499 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flame ionization detection ; Poly(styrene-co-methyl acrylate) ; Poly(methyl acrylate-co-n-butyl acrylate) ; Chemical composition distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This investigation is focused on the development of HPLC with subsequent flame ionization detection as a tool to determine the chemical composition distribution of non-or poorly UV absorbing copolymers. Experiments were carried out with poly(styrene-co-methyl acrylate) and poly(methyl acrylate-co-n-butyl acrylate) copolymers. HPLC combined with FID provided useful qualitative information. Quantitative information could be obtained after calibration.
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    Separation of glycated hemoglobin A1C by high-performance liquid chromatography on a non-porous exchanger (1991)
    Springer
    Chromatographia 31 (1991), S. 505-506 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Non-porous cation exchanger ; Hemoglobin A1C ; pH gradient elution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance ion exchange chromatography on a nonporous cation exchanger was examined for the separation of glycated hemoglobin. A standard sample of human hemoglobin was separated with salt or pH gradient elution. Glycated hemoglobin A1C was well separated from other hemoglobin variants in less than 10 minutes. pH gradient elution gave better resolution than salt gradient elution.
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    Packing meterials with surface barriers, controlled distribution and topography of ligands for sample clean-up and analysis of biologically active solutes in HPLC (1991)
    Springer
    Chromatographia 31 (1991), S. 507-511 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Restricted access packings ; Packings with surface barriers ; Sample clean-up of biologically active analytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Various types of, so-called, restricted access packings have been developed for sample clean-up and analysis of biologically active solutes by means of HPLC. The unique feature of these packings is that they prevent the access of matrix components such as protein whilst selectively retaining the drug components and their metabolites. This results from the fact that the particles of the packings possess a surface barrier for large solutes at the external or internal surface area and exhibit a controlled gradient in the chemical surface composition. They are grouped, according to their particle structures, into internal-surface reversed phases (ISRP), shielded hydrophobic phases (SHP), semi-permeable surfaces (SPS), dual zone phases (DZP) and mixed functional phases (MFP). The structural characteristics and the chromatographic properties of these packings are reviewwed, especially with regard to their use in the assaying of drugs.
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    Determination of carbonyl compounds in air by HPLC using on-line analyzed microcartridges, fluorescence and chemiluminescence detection (1991)
    Springer
    Chromatographia 32 (1991), S. 33-39 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Air analysis ; Dansylhydrazones of carbonyl compounds ; Chemiluminescence ; Fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Sensitive and selective detection of dansylhydrazones of atmospheric carbonyl compounds (aldehydes and ketones) can be achieved using high performance liquid chromatography (HPLC) with fluorescence or chemiluminescence detection. The carbonyl compounds are derivatized by drawing air through small glass cartridges packed with porous glass particles impregnated with dansylhydrazine. After sampling, the contents of the cartridges are analyzed on-line by using a small plug of water (200 μL) to transfer and focus the hydrazone derivatives at the head of a HPLC column. Greatly increased sensitivity over traditional methods derives from 1) analysis of the entire contents of the sampling cartridge, and 2) detection by fluoresence or peroxyoxalate chemilum-inescence. Results are compared for photo-initiated and H2O2-initiated peroxyoxalate chemiluminescence. This novel and practical system enables the detection of sub-ppbv concentrations of formaldehyde, acetaldehyde, acetone and higher carbonyls in air using relatively short sampling times.
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    Use of a displacement model for solvent sorption to study non-specific selectivity in reversed-phase liquid chromatography (1991)
    Springer
    Chromatographia 32 (1991), S. 13-18 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alkyl bonded phases ; Non-specific selectivity ; Hydro-organic mobile phases ; Retention of alkanoate esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A thermodynamic equation is derived for the non-specific selectivity of alkyl bonded phases as a function of the mobile phase composition using a displacement mechanism to model the sorption of solvents into the bonded phase. The equation is used to calculate the thermodynamic parameters which characterize the incremental behavior of a hydrophobic group in ethyl alkanoate and methyl perfluoroalkanoate ester solutes chromatographed with water-methanol and water-acetonitrile mobile phases on both octyl and octadecyl bonded phases.
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    High performance liquid chromatography assay for alanine amino transferase (1991)
    Springer
    Chromatographia 32 (1991), S. 23-26 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enzyme assay ; Alanine amino transferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An improved method of alanine-amino transferase determination is proposed. The reaction is carried out with alanine and 2-oxoglutarate as substrates and analysis is by HPLC on a reversed-phase chromatographic system using a C18 column and tetrabutylammonium phosphate in phosphate buffer (pH 7.0)-acetonitrile as mobile phase. The enzyme activity was determined by directly following the formation of pyruvic acid without employing any secondary reaction, which is necessary in the spectrophotometric method. The detection limit of pyruvic acid is 10 pmole μl−1 and the standard deviation for the enzymatic activity of standard solutions is 5.4%. Furthermore under the chromatographic conditions selected it is possible to detect the presence of some intermediate species.
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    High-performance liquid chromatographic determination of furfural and hydroxymethylfurfural in apple juices and concentrates (1991)
    Springer
    Chromatographia 32 (1991), S. 45-48 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Furfural ; Hydroxymethylfurfural ; Apple juice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and sensitive method for determining 2-furaldehyde (FUR) and 5-hydroxymethyl-2-furaldehyde (HMF) in apple juices and juice concentrates has been developed. The method for FUR and HMF involves the solid-liquid extraction of the juice by using a C-18 cartridge prior to reversed-phase separation with detection at 280 nm. The mobile phase was acetonitrile-water (8/92, v/v) at a flow rate of 1.0 ml/min. Recoveries from apple juices and juice concentrates spiked at different levels ranged from 94.1 to 104.0 (FUR) and 94.5 to 100.5 (HMF). The quantification limit for both, FUR and HMF, was 5 ppb.
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    Sample-induced internal pH gradients in microcolumn liquid chromatography of proteins (1991)
    Springer
    Chromatographia 32 (1991), S. 61-64 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sample-induced pH gradients ; Separation of proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The technique of an internal pH gradient induced by the sample is applied to the separation of proteins by liquid chromatography. Compatibility of the method with microcolumns is demonstrated and examples of separations on different types of sorbents are given.
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    URL: http://dx.doi.org/10.1007/BF02262468
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    Distribution behavior of some drug enantiomers in an aqueous two-phase system using counter-current extraction with protein (1991)
    Springer
    Chromatographia 32 (1991), S. 56-60 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Counter-current extraction ; Chiral resolution ; Ofloxacin enantiomers ; Aqueous two-phase system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The partial resolution of some drug enantiomers by counter-current extraction in an aqueous two-phase system using bovine serum albumin (BSA) or ovomucoid (OVM) as chiral discriminator is described. The phase system was prepared with dextran 40, polyethylene glycol and a protein. Ofloxacin (OFLX) enantiomer was well recognized by the BSA system, whereas the enantiomers of carvedilol (β-blocker) and DG-5128 (a new oral hypoglycaemic drug) were hardly recognized by the OVM system. The distribution coefficients of (S)-, (R)- and rac-OFLX varied with pH. Good enantioselectivity for OFLX was obtained at relatively high pH (≥ pH 9). The crude optically enriched OFLX enantiomers were extracted from the aqueous fractions and finally purified by thin-layer chromatography.
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    Evaluation of octadecyl-bonded alumina for separations of proteins and peptides by reversed-phase high-performance liquid chromatography (1991)
    Springer
    Chromatographia 32 (1991), S. 49-55 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Protein separations ; Peptide separations ; Octadecylalumina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A recently-developed octadecyl-bonded alumina (ODA) stationary phase was evaluated for the separation of peptides and proteins by reversed phase high performance liquid chromatography. Using standard water-acetonitrile mobile phase gradients containing 0.1 % trifluoroacetic acid, the average peak capacity obtained for the separation of a mixture of ribonuclease a, cytochrome c, lysozyme and carbonic anhydrase on an ODA column are similar to that obtained on a widely used octadecylsilane (ODS) column. However, overall chromatographic resolution of the components of this mixture on ODA is inferior to that obtained on ODS. Cytochrome c peak areas were found to be ∼50% smaller on the ODA column than on ODS. On the other hand, both peak capacities and resolutions of octapeptide mixtures were found to be generally superior on the ODA column, and peak areas for a representative octapeptide were found to be virtually identical for both ODA and ODS columns. The differences in the results obtained on the ODA and ODS columns for these separations are attributed to the smaller pore size and unique fused-microplatelet shape of the ODA particles. Comparisons of the separations of the tryptic digest of cytochrome c on the ODS and ODA columns demonstrate that the ODA phase is potentially as useful as ODS for peptide mapping applications.
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    Analysis of enantiomeric flavanones in plant extracts by high-performance liquid chromatography on a cellulose triacetate based chiral stationary phase (1991)
    Springer
    Chromatographia 32 (1991), S. 69-72 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomeric separation ; Chiral stationary phase ; Cellulose triacetate ; Flavanones ; Plant extracts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Flavanones ofArachis hypogaea, Hemizonia increscens, Eriodictyon glutinosum andThymus vulgaris extracts have been stereospecifically analysed by gradient elution on a column of cellulose triacetate supported on silica gel diol. The stereochemistry of naringenin, eriodictyol and homoeriodictyol was in favour of the 2S-configurated flavanones.
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    Studies of the influence of hydrogen chloride on the liquid chromatographic properties of amino bonded phases (1991)
    Springer
    Chromatographia 32 (1991), S. 79-81 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amino bonded phases ; Hydrogen chloride treatment ; Retention anomalies ; Normal-phase separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The influence of hydrogen chloride on the retention properties of aminopropyl bonded phases is studied using a series of simple aromatics, phenols and acids. The result of the HCL treatment is to mediate the hydrogen bonding interaction between the solute's polar functional groups and the bound amino groups.
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    Ion-pair chromatography of dianionic species by dionium reagents (1991)
    Springer
    Chromatographia 32 (1991), S. 73-78 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair separations ; Dianionic species ; Dionium reagent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Dionium cations, polymethylenebis(tributylphosphonium)s (BuCnBPs), were used as ion-pair reagents for ion-pair chromatography of dianionic species, such as maleate, fumarate, phthalates, and naphthalenedisulfonates. The longer the length of methylene chain connecting the two phosphonium cationic ceterns within BuCnBP, the larger was the retention of these dianionic species. The dionium reagents had a higher retention ability compared to conventional monoonium reagents, and enabled a higher resolution among the dianionic species of structural isomers. The extraction behavior of the dianionic species in a loctanol/water system was also investigated. The retention behavior by the use of BuCnBP was discussed in comparison with the extraction behavior.
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    Enantioseparation of α-phenylglycine by HPLC on an ODS column coated with chiral crown ether (1991)
    Springer
    Chromatographia 32 (1991), S. 82-84 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separation ; Chiral crown ethers ; Phenylglycine enantiomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Previous work has demonstrated the possibility of crcating chiral stationary phases by coating a suitable support material via the mobile phase. The result is a wide variety of chiral phase systems which can be used in liquid chromatogrphy to separate enantiomers by a liquid-solid adsorption mechanism. The present paper demonstrates the potential of this technique for chiral crown ethers incorporating an α-D-mannopyranoside unit using the separation of phenyglycine enantiomers as an example.
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    Rapid separation of some antiepileptic drugs in serum by HPLC (1991)
    Springer
    Chromatographia 32 (1991), S. 85-86 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Antiepileptic drugs ; Optimised separation ; Serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A fast and easy, iscratic high-performance liquid chromatographic method for the simultaneous determination of primidone, phenobarbital, phenytoin, carbamazepine and thiobutabarbital from serum samples has been developed. The optimal eluent composition is 36% acetonitrile, 24% methanol and 40% phosphate buffer. Using a programmable wavelength detector very low (sub-therapeutic) levels of the drugs can be measured.
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    Effect of inorganic salt concentration on the retention value in reversed phase ion-pair liquid chromatography (1991)
    Springer
    Chromatographia 32 (1991), S. 538-542 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair separation ; Salt concentration ; Charge number of solute ; Gouy-Chapman theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Thermodynamic and numerical treatments have been combined with Gouy-Chapman theory were to show that the effect of the salt concentration on the capacity factor in reversed-phase ion-pair liquid chromatography (RP-IPC) can be expressed as lnk′=A+blnCs. The parameter B is related to the charge number of the solute, and the parameter A is determined by both electrostatic and nonelectrostatic interaction, and can the linearly correlated with logarithm of the capacity factor in RP-HPLC for the solute with one negative charge. It also been observed that the electrostatic interaction is reduced with increasing salt concentration in RP-IPC, and this effect is more remarkable for solutes with more than the one negative charge of sulphonic acids.
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    Study of the efficiency of a mobile phase used in size-exclusion HPLC for the separation of peptides from a casein hydrolysate according to their hydrodynamic volume (1991)
    Springer
    Chromatographia 32 (1991), S. 499-504 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion ; Peptides ; Casein hydrolysate ; FAB-MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A casein hydrolysate was eluted on a TSK G-2000 SW sizeexclusion high-performance liquid chromatography (SE-HPLC) column using a mobile phase which gives a correlation coefficient of 0.98 for the separation of 20 pure and synthetic peptides and proteins of molecular weight (M. W.) varying from 243.28 (Ala-Pro-Gly) to 43 000 (Ovalbumine) daltons. Further isolation and purification of peptides present in each of the 8 different fractions collected from the SE-HPLC were done by reversed-phase HPLC (RP-HPLC). Peptide experimental M. W. determined from the calibration curve obtained for synthetic or purified peptides was compared to their precise M.W. obtained by fast atom bombardment-mass spectrometry analysis (FAB-MS). The results do not show a separation of this complex hydrolysate by SE-HPLC according to the hydrodynamic volume of its constituents.
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    Applicability and precision of simultaneous chromatographic determination of some characteristics of solid phases and their beds (1991)
    Springer
    Chromatographia 32 (1991), S. 514-522 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Streaming current ; Specific pore volume and surface area ; Specific weight ; Bed porosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The applicability and precision of the method allowing the determination of several characteristics of the sorbent and its bed from two simple chromatographic retention measurements were tested with porous metal oxides and some other solids. The typical time of one retention experiment is 1–3 minutes. The method was verified with chromatographic solid phases containing both mesopores and macropores. The agreement between the retention volume of the streaming current response, caused by the change in the concentration of the polar component of the binary hydrocarbon-based mobile phase, and the total volume of the liquid in the column is decisive for the applicability of the method. If the influence of the error in the determination of the sorbent's weight in the column and of the column tube's volume are neglected, the external and the total bed porosities and the specific weight of the sorbent can be determined with the relative error of the retention volume measurement. The error of the determination of the specific pore volume and internal bed porosity will be twice as much. The specific surface area can be determined approximately for sorbents with average and large surface areas.
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    High-performance liquid chromatographic assay of debrisoquine and its 4-hydroxy metabolite in human urine (1991)
    Springer
    Chromatographia 32 (1991), S. 523-526 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Debrisoquine ; Urine ; Phenotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An isocratic HPLC method is described. It allows the simultaneous determination of debrisoquine and 4-hydroxydebrisoquine in urine. Sample preparation involves a rapid and simple (one step) liquid-liquid extraction without derivatization. Separation, followed by UV-detection, is carried out on a nitrile column in reversephase mode with a binary, aqueous mobile phase. This rapid assay uses a new internal standard (guabenxane) and allows the determination of urinary concentrations with good precision and appropriate sensitivity.
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    Elution behavior of N-heterocyclic derivatives of mixed ruthenium(II)-sulfoxide complexes in reversed-phase high-performance liquid chromatography (1991)
    Springer
    Chromatographia 32 (1991), S. 546-548 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ruthenium mixed complexes ; Sulfoxides ; N-Heterocyclic bases ; Hydrophobic properties of aromatic ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The elution behaviour of a series of dichlorobis-(dimethylsulfoxide)bis(N-heterocyclic)ruthenium(II) complexes has been investigated using reversed-phase HPLC. Similar trends as those displayed by the free N-heterocyclic bases have been observed for the complexes, essentially reflecting the hydrophobic properties of the aromatic ligands.
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    Sample preparation by supercritical fluid extraction in environmental food and polymer analysis (1991)
    Springer
    Chromatographia 32 (1991), S. 527-537 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Supercritical fluid chromatography ; Supercritical fludi extraction (SFE) ; Explosives ; Cholesterol ; Polymer additives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Extraction with supercritical CO2 is a versatile method for sample clean-up and trace enrichment. The off-line coupling of SFE and HPLC is used to determine various explosives in debris as well as pesticides in soil. In food analysis the metod could be applied to determine cholesterol in noodles quantitatively. Correlations between the retention in RP chromatography and required extraction conditions could the established. The higher the organic modifier concentration in the eluent has to be, the smoother the extraction conditions required. With the non-volatile solutes studied, extraction temperature had no influence on extraction yield and speed. On-line coupling of SFE and capillary SFC is a very convenient and sensitive method for the determination of polymer additives. The coupling device described can also be used for “solventless” injection in capillary SFC.
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    Reverse-phase HPLC of organic acids in musts (1991)
    Springer
    Chromatographia 32 (1991), S. 555-558 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Organic acids ; Grape musts ; Direct injection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple method for reverse-phase HPLC analysis of organic acids present in must has been developed. It is carried out in isocratic conditions, with a weak dilute acid as eluent and U.V. detection. The aim is to minimize sample preparation merely to filtration: direct injection is proposed as an approach toin vivo conditions.
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    Optimization of isocratic mobile phase composition for HPLC analysis of eleven substituted phenols (1991)
    Springer
    Chromatographia 32 (1991), S. 566-572 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Isocratic Optimization ; Overlapping Resolution mapping method ; Substituted Phenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The Overlapping Resolution Mapping (ORM) method has been applied to predict the best mobile phase composition for the separation of eleven substituted phenols. This separation was carried out by HPLC using reversed-phase isocratic elution and UV detection with a diode array detector. The effect of temperature on the separation process was also taken into account. The optimized method was applied to identify phenols in waste and drinking water.
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    A computer routine for the selection and optimization of multisolvent mobile phase systems in reversed-phase liquid chromatography (1991)
    Springer
    Chromatographia 32 (1991), S. 559-565 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Multisolvent mobile phase ; Optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A computer program is described for the optimization of reversed-phase multisolvent separations. After four initial gradient runs are carried out, calculation will locate a possible optimum with binary systems or select two binary mixtures with respect to both the analysis time and the selectivity. In this latter case, two additional experiments will locate the true optimum on a straight line joining these two binary compositions on the solvent triangle (ternary system). The efficiency of this procedure is demonstrated with an illustrative example.
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    Separation of copoly(styrene/acrylonitrile) samples according to composition under reversed phase conditions (1991)
    Springer
    Chromatographia 32 (1991), S. 107-112 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Styrene/acrylonitrile polymers ; Gradient elution ; Solubility effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Copoly(styrene/acrylonitrile) samples (S/AN) have been repeatedly separated according to composition by gradient HPLC with alkane hydrocarbons as a starting eluent A and dichloromethane (DCM) or tetrahydrofuran (THF) as a solvent B. In these systems, retention increased with AN content of the copolymers. The chemical nature of the column packings used had almost no influence on the retention of S/AN samples. The present paper shows thatn-pentane andn-heptane, when used in a given volumetric gradient with DCM+20% methanol as a solvent B, lead to identical solution characteristics of S/AN on silica columns. A similar result was obtained on C18 columns withn-heptane or cyclohexane, whereas gradient elution with toluene as a starting eluent caused insufficient resolution. Reversed phase separation of S/AN copolymers could be achieved on polystyrene gel columns through gradients with methanol as a starting eluent and DCM or THF as a solvent B. In both systems, retention decreased with increasing AN content of the copolymers. The elution characteristics were almost linear in the range 0–20 wt% AN. This behaviour can be understood in the context of polymer solubility: in both systems, the solubility borderline of S/AN has a distinct maximum at about 25 wt% AN. Reversed phase separation was achieved at the lefthand slope of these curves where the dissolution of a sample with a higher AN content requires less DCM or THF solvent than the dissolution of copolymers which are poorer in AN. This idea predicts that samples with more than 25 wt% AN should elute later than S/AN whose composition is near to the solubility maximum. This indeed was found with a copolymer containing 36.2 wt% AN.
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    Improved HPLC methodology in occupational exposure studies on formaldehyde (1991)
    Springer
    Chromatographia 32 (1991), S. 113-115 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Formaldehyde in air ; Dinitrophenyl hydrazine ; Occupational hygiene studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This work describes an HPLC method for the determination of formaldehyde concentration in air. Traps containing 20–40 mesh silica gel coated with 2,4-dinitrophenylhydrazine (DNPH) are used. After aspiration of air the traps are eluted with methanol. The hydrazone formed is then separated on a C18 column using a mobile phase of methanolwater (50–50 v/v). The effluent is monitored with a UV detector at 365 nm. To calibrate and to compare this method with that of Niosh 2502 (traps coated with 2 benzylamino ethanol on Chromosorb 102), a mixing chamber that generated atmospheres of known concentration of formaldehyde was used.
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    Identification of by-products in phenylisocyanate pre-column derivatization by thermospray liquid chromatography-mass spectrometry (1991)
    Springer
    Chromatographia 32 (1991), S. 125-129 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenylisocyanate derivatization ; By-products of derivatization ; Thermospray LC/MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Thermospray liquid chromatography-mass spectrometry has been applied to the identification of by-products in precolumn derivatization by phenylisocyanate. These byproducts are eluted early in the same chromatographic region as the low molecular weight derivatives and were located by chromatographic analysis of a blank sample. Their identification would offer further qualitative information in the use of phenylisocyanate as a derivatizing agent. Five compounds resulted from the reaction of phenylisocyanate and the reaction medium were identified: two from a reaction between phenylisocyanate and methanol, two from the reaction between phenylisocyanate and water, and one from the polymerisation of phenylisocyanate.
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    Determination of micelle-solute association constants of some benzene and naphthalene derivatives by micellar high-performance liquid chromatography with butanol and sodium chloride additives to mobile phase (1991)
    Springer
    Chromatographia 32 (1991), S. 148-154 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micelle-solute association constants ; Benzene and naphthalene derivatives ; Butanol and NaCl additives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The interaction between some benzene and naphthalene derivatives and sodium dodecyl sulphate and hexadecyltri-methylammonium bromide in the presence of n-butanol and sodium chloride has been evaluated by high-performance liquid chromatography using micellar mobile phases. Micelle-solute association constants are given for the compounds investigated. The results show that addition of n-butanol to the mobile phase decreases the association constant values relative to those in the absence of any additive. Conversely, when sodium chloride is added to the mobile phase, an increase of the association constant is obtained in most cases. Good correlation between free energy of transfer for water-micelles and for octanol-water has been observed.
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    Dependence of the retention volumes of additional streaming current responses and of the column void volume on mobile phase composition (1991)
    Springer
    Chromatographia 32 (1991), S. 130-136 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Streaming current ; Column interparticle volume ; Column void volume ; Column hold-up volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The influence of the alcohol content of the mobile phase and water, acetic acid and aniline as mobile phase additives on the generation and shape of two additional changes of the streaming current, generated inside the liquid chromatography column by injection of any sample and recorded before the responses of retained solutes, was studied in a normal-phase system using silica gel as the stationary phase. The mobile phases were based on a n-heptane-1-propanol mixtures. Under the same conditions the relationships between the column interparticle volume, the column void volume and the total liquid volume in the column and the retention volumes of these two streaming current responses, having the form of chromatographic peaks, were studied. The column void volume was identified with the retention volume of n-octane. The total liquid volume in the column (column hold-up) was calculated from the weight loss of the column wetted with water at first and then dried in nitrogen stream. The retention volume of the first streaming current response equals the column interparticle volume disregarding the mobile phase composition. If the 95∶5 n-heptane-1-propanol mobile phase contains water up to 80% of its saturated concentration (up to 0.114% by vol.), the retention volume of the second response agrees with the total volume of the liquid in the silica gel column, with a precision better than 2%. At a higher relative water saturation the retention volume of the second response increases, while the column void volume decreases. Both changes are explained by the spontaneous formation of a highly polar stagnant liquid in the pores of the silica gel.
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    Liquid chromatography of erythromycin A and related substances on poly(styrene-divinylbenzene) (1991)
    Springer
    Chromatographia 32 (1991), S. 162-166 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Erythromycin A and related substances ; Poly(styrene-divinylbenzene)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An isocratic liquid chromatography method for assay and purity control of erythromycin is presented. Erythromycin A is separated from all its potential impurities, except erythromycin D. The selectivity depends on the pore size of the poly(styrene-divinylbenzene) stationary phase. Wide pore PLRP-S 8 μm 1000 Å shows the best selectivity. The column is heated at 70°C. The mobile phase is acetonitrile-2-methyl-2-propanol-0.2 M potassium phosphate buffer pH 9.0-water (3:16.5:5:75.5). The flow rate is 2 ml/min. UV detection is performed at 215 nm. The total analysis time is about 30 min. The method was used to compare official standards.
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    Poly(methylglutamate)-coated surfaces in HPLC and CE (1991)
    Springer
    Chromatographia 32 (1991), S. 171-178 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary Electrophoresis ; Surface Coating ; Poly(methyglutamate)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Thermal polymerization of the N-carboxyanhydride of glutamic acid-5-methylester was used to coat microparticulate silica and the surface of capillaries with poly(methylglutamate) (PMG). By increasing the thickness of the PMG layer the hydrophobicity of the stationary phases could be increased. However, total shielding of surface silanols was not achieved. The PMG-coated silicas for HPLC showed unexpected and strange behavior in the chromatography of proteins. Nevertheless, capillaries coated with PMG proved to be excellent for highly efficient CE separations of proteins at medium pH values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02325022
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    Porous copolymer-based cation exchanger for the off-line preconcentration of aromatic amines from water (1991)
    Springer
    Chromatographia 32 (1991), S. 167-170 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous copolymer-based cation exchanger ; Solid-phase extraction ; Aromatic amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A weakly polar porous copolymer and the sulfonic acid cation exchanger based on this copolymer were tested as sorbents for off-line preconcentration of aromatic amines from water. Minicolumns packed with the 1,4-di(methacryloyloxymethyl)naphthalene—divinylbenzene copolymer and the cation exchanger were used for the solid-phase extraction of polar amines. In order to study the sorption properties of these polymeric materials, the recoveries and breakthrough volumes ofp-aminophenol,o, m andp-phenylenediamine, aniline,o andp-anisidine,p-nitroaniline, ando-toluidine were determined.
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    URL: http://dx.doi.org/10.1007/BF02325021
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  • 88
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    An application of fast protein liquid chromatography (FPLC) in the purification of retinol binding protein from rat serum (1991)
    Springer
    Chromatographia 32 (1991), S. 229-232 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Affinity chromatography ; SDS-PAGE ; Ultrafiltration ; Retinol binding protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retinol Binding Protein (RBP) is the specific plasma protein for the transport of retinol from liver to peripheral tissues. It is a single polypeptide chain of approximately 21 KDa, and circulates as a 1∶1 molar complex with transthyretin (TTR). The relative low concentration in plasma (40–50 μg/ml and its chromatographic behaviour on ionic exchangers render the purification of rat RBP particularly laborious. In this paper we report a simple and semi-automatic method for the preparative purification to homogeneity of rat serum RBP. The method includes: (1) Selective removal of albumin by affinity chromatography on a Blue Sepharose column; (2) Chromatography on a Mono Q strong anion exchange column; (3) Dissociation of the RBP-TTR complex by 3 M urea; (4) Concentration, desalting and freeze drying. The purified RBP has been used for the production in rabbit of antirat RBP specific antibodies for studies on nutritional control of RBP synthesis and metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276245
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  • 89
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    Retention behavior of some monobasic penicillins and their quaternary ammonium ion pairs in reversed-phase high-performance liquid chromatography (1991)
    Springer
    Chromatographia 32 (1991), S. 436-440 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair chromatography ; Quaternary ammonium ion pairs ; Penicillins ; Retention behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behavior of some monobasic penicillins (penicillin G, penicillin V, oxacillin, cloxacillin and dicloxacillin) and their quaternary alkylammonium ion pairs has been studied in a reversed-phase high-performance liquid chromatographic system using Partisil 5 μm ODS-3 asstationary phase and mixtures of acetonitrile and aqueous phosphate buffers as mobile phases. The influence of pH, pairing-ion chain length and concentration, and column temperature on retention has been investigated and the observed behavior of the compounds during the chromatographic process has been discussed.
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    URL: http://dx.doi.org/10.1007/BF02327974
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  • 90
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    A quantitative study of the adsorption effect on the retention of dicarboxylic acids in ion-exclusion chromatography (1991)
    Springer
    Chromatographia 32 (1991), S. 453-456 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-exclusion ; Retention ; Adsorption effects ; Dicarboxylic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention values and distribution coefficients for C4−C9 dicarboxylic acids on a column packed with cation exchange resin in the H+ form were determined, using dilute HCl solution as eluent. Based on the Donnan membrane equilibrium and adsorption equilibrium, adsorption coefficients were evaluated, and the adsorption contributions to the retention of these analytes were estimated.
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    URL: http://dx.doi.org/10.1007/BF02327977
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  • 91
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    Determination of polar pollutants in water using an on-line liquid chromatographic preconcentration system (1991)
    Springer
    Chromatographia 32 (1991), S. 445-452 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; On-line preconcentration ; Polar pollutants ; Water (tap and surface)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An isocratic column liquid chromatographic system with UV absorbance detection at 230 nm has been developed for the rapid trace-level determination of a large number of polar pollutants in water. The systems contains two precolumns, in series, which are packed with a styrenedivinylbenzene (PLRP-S) polymer. The second precolumn is also loaded with sodium dodecylsulphate before use. Each precolumn is combined with a PLRP-S analytical column, and aqueous acetonitrile mixtures (pH 3) are used for the separation of neutral as well as acidic and basic pollutants. With 10-ml water samples the detection limits for all analytes, in tap water, are in the low to sub μg/l range. Relevant analytical data are reported and the advantage of using a dodecylsulphate-loaded precolumn over a cation-exchange precolumn is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02327976
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  • 92
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    Determination and quantification of dimethyl sulphoxide by HPLC (1991)
    Springer
    Chromatographia 32 (1991), S. 461-462 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; DMSO in water and wastewater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatographic method has been developed for detecting and quantifying dimethyl sulphoxide (DMSO) in water and especially in wastewater. The detection limit for the quantification of DMSO is 0.5 ppm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02327979
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  • 93
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    Analysis of the soluble proteins in grape musts by reversed-phase HPLC (1991)
    Springer
    Chromatographia 32 (1991), S. 463-465 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Grape musts ; Soluble proteins ; Simplex optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase high performance liquid chromatography (RP-HPLC) was applied to the analysis of the soluble proteins from grape musts, with protein separation based on hydrophobicity. The initial percentage and rate of increase of organic modifier were optimized using the Modified Simplex method. Both the qualitative and quantitative data in the chromatograms yielded information on the variety origin of grape musts.
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    URL: http://dx.doi.org/10.1007/BF02327980
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  • 94
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    Reversed-phase ion-interaction chromatography of metal ions by EDTA precomplexation (1991)
    Springer
    Chromatographia 31 (1991), S. 539-543 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-interaction chromatography ; EDTA complexes ; Heavy metal ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Conditions for the isocratic separation by reversed-phase ion-interaction chromatography of Bi(III), Fe(III), Co(III), Ni(II), Cu(II) and Pb(II) chelates with ethylenediaminetetraacetic acid have been studied using UV-Vis detection. Both chromatographic and spectrophotometric conditions for the determination of these metal chelates are discussed including ion-interaction reagent concentration, water/methanol ratio, ionic strength, pH and absorbing wavelengths. Detection limits are particularly satisfactory for Bi(III), Fe(III) and Co(III) chelates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02279472
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  • 95
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    Comparison of 20 normal phase LC systems for separation of chalcones (1991)
    Springer
    Chromatographia 31 (1991), S. 575-582 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phases ; Normal phase analysis ; Chalcones ; Factor analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention of 36 E-s-cis and Z-s-cis chalcone isomers has been measured using 20 normal phase HPLC systems containing the chemically-bonded stationary phases, Zorbax ODS, LiChrospher 100 Diol and Spherisorb AP (n-propylpicryl ether bonded to silica gel), with a variety of mobile phase modifiers. Tetentivity and the specific properties of these chromatographicsystems are considered. The experimental results were processed using correspondence factor analysis and hicrarchical ascending classification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02279478
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  • 96
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    Estimation of dead-time in liquid chromatography from retention behaviour of homologous series by non-linear regression (1991)
    Springer
    Chromatographia 31 (1991), S. 544-548 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dead time ; Homologous series ; Non-linear regression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary There is still no generally accepted method for determining the dead-time in liquid chromatography. Calculation of the dead-time from retention times of homologous series is often said to be accurate and convenient [1–3]. This method is not often used, however, because the algorithms emplyed take too much time or can only be used in special cases. The method of calculation described here overcomes these problems. The algorithm is not only fast but uses straightforward mathematics.
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    URL: http://dx.doi.org/10.1007/BF02279473
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    Comparison of extraction methods for the determination of polycyclic aromatic hydrocarbons in soot samples (1991)
    Springer
    Chromatographia 31 (1991), S. 569-574 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Polycyclic aromatic hydrocarbons ; Soot and air samples ; Liquid CO2 extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The results of the analysis of polycyclic aromatic hydrocarbons (PAH) in soot and similar types of sample are often dependent on the extraction method applied, owing to carbonaceous substances present in these samples. The recoveries of three extraction methods, and ultrasonic ether, a Soxhlet toluene and a Soxhlet extraction with liquid CO2 were compared for a typical soot sample. Additionally the CO2 extraction was optimized with respect to the necessary number of transfers during the extraction and the proper method to remove the CO2 after extraction. Finally, the liquid chromatographic pretreatment of the extract, prior to gas chromatographic analyses of the PAH, was improved.
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    URL: http://dx.doi.org/10.1007/BF02279477
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  • 98
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    Chromatographic behaviour of homologous amines: Comparison of derivatizing agents, columns and mobile phases (1991)
    Springer
    Chromatographia 31 (1991), S. 41-49 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amines ; Retention mechanism ; Separation factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The liquid chromatographic behaviour of aliphatic mono- and polyamines belonging to different homologous series has been investigated using various pre-column derivatizing agents (OPA and CNB), mobile phases (water-MeOH and water-ACN), RP columns (different packing sizes and shapes) and detectors (UV and fluorescence) in order to characterize the different contributions to retention and the different selectivities under the conditions investigated. The parameters derived allowed computation of capacity factors in good agreement with experiments. The chromatographic method optimized with respect to OPA derivatization has been successfully utilized for the determination of putrescine, cadaverine and 2-phenyl-ethylamine in cheese samples under different ageing conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290494
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  • 99
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    Retention behavior of dipeptide isomers in reversed-phase high-performance liquid chromatography (1991)
    Springer
    Chromatographia 31 (1991), S. 27-30 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dipeptide isomers ; Retention variations ; van der Waals volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effects of eluent pH and organic modifier concentration on the capacity factor (k′) and selectivity of dipeptide isomers were investigated. It has been observed that the variation in the logarithm of the capacity factor of the dipeptide isomers is linearly dependent on the organic modifier concentration (Cb), however, the selectivity is almost independent of it. Both capacity factor and selectivity were seriously affected by the pH of the eluent. Both the capacity factor and the intercept of the ln k′ vs. Cb plot increased with increasing van der Waals volume of the non-polar amino acid subunit of the dipeptides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290492
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  • 100
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    Stereochemical resolution of enantiomeric 2-aryl propionic acid non-steroidal anti-inflammatory drugs on a human serum albumin based high-performance liquid chromatographic chiral stationary phase (1991)
    Springer
    Chromatographia 31 (1991), S. 55-59 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separations ; Non-steroidal anti-inflammatory drugs ; Immobilized human serum albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The native enantioselectivity in binding of human serum albumin (HSA) towards 2-aryl propionic acid non-steroidal anti-inflammatory drugs (2-APA-NSAIDs, the “profens”) was found to be preserved when the protein was immobilized within a commercially available diol high-performance liquid chromatographic column. High capacity factors were obtained, reflecting the previously observed extensive binding of the 2-APA-NSAIDs to free HSA. The capacity factors were modified by the addition of octanoic acid to the mobile phase. Chiral resolution of the enantiomers of all nine 2-APA-NSAIDs studied was achieved. Preliminary studies show that in addition to being a useful chiral analytical tool for this therapeutically important series of compounds, the HSA chiral stationary phase may provide useful information on the affinity and binding mechanism of small molecules to HSA.
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    URL: http://dx.doi.org/10.1007/BF02290496
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