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  • Column liquid chromatography  (54)
  • Escherichia coli  (36)
  • ASTROPHYSICS
  • Data analysis / ~ processing
  • Industrial Chemistry
  • Inorganic Chemistry
  • NOISE
  • Seismology
  • ddc:330
  • Springer  (91)
  • DGG  (1)
  • Fed. Inst. Techn., No. 101  (1)
  • 1985-1989  (93)
  • 1950-1954
  • 1987  (93)
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Keywords
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  • 1985-1989  (93)
  • 1950-1954
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  • 1
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    Pattern recognition for earthquake detection by mental pictures (1987)
    Springer
    In:  Bull., Polar Proj. OP-O3A4, ASST'87, Berlin, Springer, vol. 81A, no. 16, pp. 347-350, (ISBN: 3-540-23712-7)
    Details
    Publication Date: 1987
    Keywords: Detectors ; Seismology ; Pattern recognition
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    BIBLIOGRAPHY SEISMOLOGY
  • 2
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    A seismic network with loosely coupled remote stations (1987)
    Fed. Inst. Techn., No. 101
    In:  Bull., Polar Proj. OP-O3A4, Proc. XX. General Assembly of ESC 1986 at Kiel, Zürich, Fed. Inst. Techn., No. 101, vol. 81A, no. 16, pp. 117-127, (ISBN: 3-540-23712-7)
    Details
    Publication Date: 1987
    Keywords: Seismic networks ; arc ; COS ; dbm ; BUG ; Seismology ; Nearfield
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    BIBLIOGRAPHY SEISMOLOGY
  • 3
    facet.materialart.
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    Automatische Detektion und Auswertung in Seismischen Netzen (1987)
    DGG
    In:  47. DGG-Tagung, Clausthal, DGG, vol. C 560, 183 pp., no. GL-TR-89-0143, pp. 235, (ISBN 3-933346-037)
    Details
    Publication Date: 1987
    Keywords: Data analysis / ~ processing ; Detectors ; ARR ; arc ; BUG ; Seismology ; Pattern recognition ; Seismic networks
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    BIBLIOGRAPHY SEISMOLOGY
  • 4
    Electronic Resource
    Electronic Resource
    Nucleotide composition and kinetic complexity of the genomic DNA of an intracellular symbiont in the pea aphidAcyrthosiphon pisum (1987)
    Springer
    Journal of molecular evolution 24 (1987), S. 205-211 
    Details
    ISSN: 1432-1432
    Keywords: Endosymbiont ; Aphid ; Genome size ; Nucleotide composition ; Cell organelle ; Mycoplasma ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An intracellular symbiont was isolated from the mycetocyte of the pea aphidAcyrthosiphon pisum, and its genomic DNA was compared with those ofEscherichia coli andMycoplasma capricolum with respect to nucleotide composition and kinetic complexity. Thermal dissociation, CsCl density equilibrium centrifugation, and high-performance liquid chromatography of the nuclease P1 digest all indicated that the G+C content of the endosymbiont DNA is as low as 30%. In this respect, the endosymbiont resembledMycoplasma species. The reassociation kinetics of genomic DNA labeled by nick translation suggested that the endosymbiont genome is 1.4×1010 daltons in size, about 5 and 18 times as large as those ofE. coli andM. capricolum, respectively. The results were confirmed by reassociation of endosymbiont DNA labeled by incubation with [3Hthymidine in Grace's medium. The endosymbiont genome of the aphid was about 500 times larger than those of leafhopper endosymbionts previously analyzed by ultracentrifugation. These characteristic properties of the aphid endosymbiont genome are discussed in connection with the evolution of cell organelles, and with reference to a previous finding that most of the genes of the aphid endosymbiont are not expressed when present intracellularly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02111233
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  • 5
    Electronic Resource
    Electronic Resource
    Cytosine deaminase that hydrolyzes creatinine to N-methylhydantoin in various cytosine deaminase-forming microorganisms (1987)
    Springer
    Archives of microbiology 147 (1987), S. 58-63 
    Details
    ISSN: 1432-072X
    Keywords: Creatinine deimination enzymes ; Creatinine deiminase ; Cytosine deaminase ; Creatinine degradation ; N-Methylhydantoin ; Creatinine ; Cytosine ; Pseudomonas putida 77 ; Cytosine deaminase induction ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Creatinine deimination has been newly detected in the following various cytosine deaminase-forming microorganisms: Escherichia coli, Proteus mirabilis, Pseudomonas aureofaciens, Pseudomonas chlororaphis and Pseudomonas cruciviae. All these microorganisms, except for E. coli, formed cytosine deaminase in a constitutive or repressive way. P. putida 77 and E. coli showed highly increased formation of creatinine deiminase in the presence of creatinine and cytosine. Throughout serial DEAE-Sephacel and Sephacryl S-300 column chromatographies, the cytosine deaminases of these microorganisms, except for that of P. ovalis, were found to hydrolyze both creatinine and cytosine at comparable rates. No concrete evidence was obtained for the presence of any other protein that hydrolyzed creatine and/or cytosine than the cytosine deaminases in the three test microorganisms randomly selected for investigation. Different from P. putida 77, none of the test microorganisms degraded N-methylhydantoin; neither N-methylhydantoin amidohydrolase nor N-carbamoylsarcosine amidohydrolase was formed in the presence of creatinine in these microorganisms. As a result, the wide occurrence of cytosine deaminases in microorganisms was found to be related to the wide distribution of those microorganisms which hydrolyze creatinine to N-methylhydantoin without further degradation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00492905
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  • 6
    Electronic Resource
    Electronic Resource
    Evolutionary relationship between Enterobacteriaceae: comparison of the ATP synthases (F1F0) of Escherichia coli and Klebsiella pneumoniae (1987)
    Springer
    Archives of microbiology 148 (1987), S. 187-192 
    Details
    ISSN: 1432-072X
    Keywords: F1F0 ATP synthase ; Escherichia coli ; Klebsiella pneumoniae ; Phylogenetic relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ATP synthase complex of Klebsiella pneumoniae (KF1F0) has been purified and characterized. SDS-gel electrophoresis of the purified F1F0 complexes revealed an identical subunit pattern for E. coli (EF1F0) and K. pneumoniae. Antibodies raised against EF1 complex and purified EF0 subunits recognized the corresponding polypeptides of EF1F0 and KF1F0 in immunoblot analysis. Protease digestion of the individual subunits generated an identical cleavage pattern for subunits α, β, γ, ε, a, and c of both enzymes. Only for subunit δ different cleavage products were obtained. The isolated subunit c of both organisms showed only a slight deviation in the amino acid composition. These data suggest that extensive homologies exist in primary and secondary structure of both ATP synthase complexes reflecting a close phylogenetic relationship between the two enterobacteric tribes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414810
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  • 7
    Electronic Resource
    Electronic Resource
    Cloning and sequence of the mdh structural gene of Escherichia coli coding for malate dehydrogenase (1987)
    Springer
    Archives of microbiology 149 (1987), S. 36-42 
    Details
    ISSN: 1432-072X
    Keywords: Catabolite repression ; Genetics ; Malate dehydrogenase ; Molecular cloning ; Sequence ; CRP binding site ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The malate dehydrogenase gene of Escherichia coli, which is susceptible to catabolite and anaerobic repression, has been cloned using plasmic pLC32-38 of Clarke and Carbon (1976). The nucleotide sequence was determined of a 2.47 kbp fragment, containing the mdh structural gene. All information necessary for expression of the mdh structural gene was mapped within a 1.3 kbp SphI-BstEII fragment. Compared with the untransformed wild type, transformations with pUC19 vector, containing this fragment, gave up to 40-fold more malate dehydrogenase activity in both E. coli wild type and mdh mutant recipients. Catabolite repression was not affected in the transformants. A possible CRP binding site in the promotor region of the mdh gene provides evidence for a co-regulation with fumA gene, the structural gene of fumarase, which is also subject to catabolite repression. The structures for transcription initiation and termination were similar to those previously described for E. coli. Amino acid sequence homologies between pro- and eucaryotic malate dehydrogenases are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423133
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  • 8
    Electronic Resource
    Electronic Resource
    Osmoregulation in Escherichia coli by accumulation of organic osmolytes: betaines, glutamic acid, and trehalose (1987)
    Springer
    Archives of microbiology 147 (1987), S. 1-7 
    Details
    ISSN: 1432-072X
    Keywords: Escherichia coli ; Osmoregulation ; Glycine betaine ; Proline betaine ; γ-Butyrobetaine ; Trehalose ; Glutamic acid ; Nuclear magnetic resonance spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It has been shown previously that externally added glycine betaine is accumulated in Escherichia coli in response to the external osmotic strength. Here we have shown, by using nuclear magnetic resonance spectroscopy and radiochemical methods, that E. coli growing in a glucose-mineral medium of elevated osmotic strength generated with NaCl, had the same capacity to accumulate proline betaine and glycine betaine. Its capacity to accumulate γ-butyrobetaine was, however, 40 to 50% lower. Accordingly, externally added proline betaine and glycine betaine stimulated aerobic growth of osmotically stressed cells equally well, and they were more osmoprotective than γ-butyrobetaine. In cells grown at an osmotic strength of 0.64, 1.01, or 1.47 osmolal, respectively, the molal cytoplasmic concentration of the two former betaines corresponded to 29, 38, or 58% of the external osmotic strength. Nuclear magnetic resonance spectroscopy revealed that trehalose and glutamic acid were the only species of organic osmolytes accumulated in significant amounts in cells grown under osmotic stress in glucosemineral medium without betaines. Their combined molal concentration in the cytoplasm of cells grown at 1.01 osmolal corresponded to 27% of the external osmotic strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00492896
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of organic nitrogen and glucose on the production of recombinant human insulin-like growth factor in high cell densityEscherichia coli fermentations (1987)
    Springer
    Journal of industrial microbiology and biotechnology 2 (1987), S. 181-186 
    Details
    ISSN: 1476-5535
    Keywords: Recombinant human insulin-like growth factor ; Escherichia coli ; Fermentation ; Production ; Somatomedin C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Two kinds of fed batch fermentation processes were compared at a 10-liter scale to examine their effect on recombinant human insulin-like growth factor (IGF-1) gene expression inEscherichia coli. The difference between the two processes was the feed medium composition and whether the process used a single or dual feed during the course of the fermentation. In the dual feed system, organic nitrogen was delivered at a higher rate (50 g/h) than in the single feed system (5 g/h). The dual feed process resulted in a significant increase in IGF-1 yield. 30 mg IGF-1/g dry cell weight was synthesized in the dual feed system compared to 3 mg IGF-1/g dry cell weight obtained in the single feed system. The presence of high levels of organic nitrogen during the induction period may enhance IGF-1 synthesis by protecting the IGF-1 from proteolytic degradation. The IGF-1 yield decreased to 17 mg/g dry cell weight when the glucose supply was decreased from 17 g/h to 8 g/h during the induction period; however, an increase in glucose supply from 17 g/h to 50 g/h during the induction period did not enhance the IGF-1 synthesis. Thus, the enhancement of IGF-1 gene expression in the dual feed process was mainly dependent on a high level of organic nitrogen and an appropriate level of glucose in the medium during the induction period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569426
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of linker insertions on the biogenesis and functioning of the Escherichia coli outer membrane pore protein PhoE (1987)
    Springer
    Molecular genetics and genomics 208 (1987), S. 485-489 
    Details
    ISSN: 1617-4623
    Keywords: PhoE porin ; Escherichia coli ; Insertion mutagenesis ; Topology ; Biogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To study the effects of small insertions on the biogenesis and functioning of outer membrane pore protein PhoE of Escherichia coli K12, oligonucleotides were inserted at five different sites in the phoE gene. The proteins encoded by the mutant alleles all appeared to be incorporated into the outer membrane since cells producing these proteins bound either phages specific for the PhoE protein or monoclonal antibodies or both. However, one mutant protein was apparently not incorporated normally since expression of this protein was lethal and the protein did not function as a pore. Amino acid residues 75 and 280 of the PhoE protein appear to be exposed on the cell surface because insertions at these sites interfere with the binding of PhoE-specific phages or monoclonal antibodies to whole cells, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328144
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  • 11
    Electronic Resource
    Electronic Resource
    Regulation of major outer membrane porin proteins of Escherichia coli K 12 by pH (1987)
    Springer
    Molecular genetics and genomics 208 (1987), S. 511-517 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; pH ; Outer membrane proteins ; Protein and operon fusions ; Osmosensor EnvZ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electrophoretic analysis of total membrane proteins of Escherichia coli cells grown at neutral or acid pH showed that ompF, ompC and lamB porin gene expression was regulated by changes in extracellular pH. Growth at acid pH was correlated with a decrease in outer membrane proteins OmpF and LamB and an increase in protein OmpC. pH-induced effects were confirmed and quantitatively estimated by using strains carrying ompF-lacZ, ompC-lacZ and lamB-lacZ fusions. Our studies showed that the pH-dependent regulation acted at a transcriptional level on ompF and ompC gene expression and also at a post-transcriptional level on ompF gene expression. Similar studies carried out with envZ strains showed that the pH-controlled transducing signal was mediated via the EnvZ protein, although other pH-dependent pathways were also involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328148
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  • 12
    Electronic Resource
    Electronic Resource
    Heat-shock induction of RNA polymerase sigma-32 synthesis in Escherichia coli: Transcriptional control and a multiple promoter system (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 10-15 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; RNA polymerase ; rpoH ; Heat-shock ; Multiple promoters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transcriptional start sites of the rpoH gene which codes for a minor σ factor (σ32) of Escherichia coli RNA polymerase were determined. The rpoH gene is transcribed, both in vivo and in vitro, from two major (P1 and P2) and one minor (P2*) promoters. In vitro synthesis of the rpoH mRNAs is dependent on the major species of RNA polymerase holoenzyme (Eσ70) but not on the minor one (Eσ32). S1 nuclease analysis of the in vivo RNA showed that the level of rpoH transcript from the downstream P2 promoter increases rapidly when E. coli cells are transferred from 30° C to 42° C, while the transcript from the upstream P1 promoter remains at a constant level. Under these conditions, the metabolic stabilities of rpoH mRNAs are virtually unaffected, suggesting that the synthesis of rpoH mRNA from the P2 promoter is specifically enhanced upon heatshock.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337752
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  • 13
    Electronic Resource
    Electronic Resource
    Genetic and physical analysis of plasmid genes expressing inducible resistance of tellurite in Escherichia coli (1987)
    Springer
    Molecular genetics and genomics 208 (1987), S. 288-293 
    Details
    ISSN: 1617-4623
    Keywords: Tellurium resistance ; Inducible ; Plasmid ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A large (〉250 kb) conjugative plasmid, pMER610, specifying resistance to tellurium and mercury was isolated from an Alcaligenes strain and transferred by conjugation to Escherichia coli AB1157. The acquisition of pMER610 by AB1157 increased the resistance to both tellurite and tellurate by 100-fold. Expression of tellurite resistance by pMER610 and the cloned Ter determinant was inducible by prior exposure to tellurite at levels sub-toxic to the sesitive AB1157. Physical analysis of the cloned Ter fragment located the resistance determinant to a 3.55 kb region. Insertion of Tn 1000 (γδ) into this region produced two classes of sensitive mutations, fully sensitive and intermediate or hyposensitive, which map in adjacent regions and form two complementation groups. Maxicell analysis identified four polypeptides (15.5, 22, 23 and 41 kDa) expressed by the Ter clone. The 23 kDa polypeptide may not be required for resistance since tellurium-sensitive γδ insertion mutations were not detected in the 23 kDa coding region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330455
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  • 14
    Electronic Resource
    Electronic Resource
    The Escherichia coli cell division proteins FtsY, FtsE and FtsX are inner membrane-associated (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 504-508 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Cell division ; ftsE ; Operon ; Membrane location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cell division genes ftsY, ftsE and ftsX form an operon mapping at 76 min on the Escherichia coli chromosome. The protein products of these genes have been indentified previously. We have studied the cellular location of the radiolabelled Fts proteins using maxicells and standard fractionation procedures. Previous protein sequence homologies suggested an inner membrane location for FtsE. We have confirmed this predicted location and have shown that FtsY and FtsX are also inner membrane-associated. These results are igreement with the hypothesis that FtsE may act at the inner membrane, in a “septalsome” complex, by coupling ATP hydrolysis to the process of bacterial cell division.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327204
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  • 15
    Electronic Resource
    Electronic Resource
    Multivalent regulation of the nusA operon of Escherichia coli (1987)
    Springer
    Molecular genetics and genomics 206 (1987), S. 185-191 
    Details
    ISSN: 1617-4623
    Keywords: nuA operon ; Regulation ; RNA polymerase ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The rate of synthesis and intracellular content of the NusA protein, a transcription termination factor, were determined for wild-type and nusA and/or nusB mutants of Escherichia coli. Both the rate and content of NusA in wild-type strains were similar to that of the RNA polymerase σ subunit, a transcription initiation factor, on a molar basis, and about 30%–40% the levels of RNA polymerase ββ′ subunits. At the stationary phase of cell growth, the values increased in parallel for both transcription factors up to approximately the level of the ββ′ subunits. In nus mutants, the rate of synthesis and the content of the σ subunit were significantly increased. These observations together suggest that the two transcription factors are coordinately regulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333573
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  • 16
    Electronic Resource
    Electronic Resource
    OriC plasmids do not affect timing of chromosome replication in Escherichia coli K12 (1987)
    Springer
    Molecular genetics and genomics 209 (1987), S. 188-192 
    Details
    ISSN: 1617-4623
    Keywords: oriC ; Escherichia coli ; Density shift ; Interreplication time ; Rate-limiting event
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The variability of the time interval between successive rounds of chromosome replication was estimated by density-shift experiments, by measuring the conversion of heavy DNA to hybrid density and light DNAs upon transfer of a steady-state culture growing in medium with [13C]glucose and 15NH4Cl to medium with light isotopes. The coefficient of variation (CV%) for the interreplication time of the Escherichia coli K12 chromosome was found to be 17%, i.e. similar to that for interdivision time. The presence of additional copies of oriC in the cell on a high copy number plasmid did not increase the CV of interreplication time. It is concluded that a single rate-limiting event is unlikely to time the initiation of chromosome replication. The regulation of initiation at oriC and the coordination with cell division is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329857
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  • 17
    Electronic Resource
    Electronic Resource
    Intraplasmid recombination in Streptomyces lividans 66 (1987)
    Springer
    Molecular genetics and genomics 209 (1987), S. 154-158 
    Details
    ISSN: 1617-4623
    Keywords: Recombination ; Plasmid ; Streptomyces ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An Escherichia coli-Streptomyces shuttle plasmid pIF132 containing two direct mel repeats was constructed. While pIF132 replicated relatively stably in E. coli (Rec+ or recA), its structure was unstable in S. lividans: recombination between the mel repeats resulted in a smaller plasmid, pIF138. Furthermore, pIF132 formed oligomers extensively in E. coli but not in S. lividans.
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    URL: http://dx.doi.org/10.1007/BF00329851
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  • 18
    Electronic Resource
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    Nucleotide sequence of putP, the proline carrier gene of Escherichia coli K12 (1987)
    Springer
    Molecular genetics and genomics 208 (1987), S. 70-75 
    Details
    ISSN: 1617-4623
    Keywords: Proline carrier gene ; putP ; Escherichia coli ; DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of the putP gene coding for the proline carrier in Escherichia coli has been determined and the amino acid sequence of the proline carrier deduced from it. The proline carrier is predicted to consist of 502 amino acids, resulting in a molecular weight of 54,343. The predicted protein is very hydrophobic (70% nonpolar amino acids), and its hydropathy profile suggests that it is composed of 12 hydrophobic segments with a mean length of 24.4 residues/segment. If these segments are assumed to be α-helical, the mean length of each domain corresponds to the thickness of the hydrophobic core of the membrane. Potential promoter, catabolite gene activator protein (CAP) binding sites and several palindromic sequence, which might be regulatory regions by the putA gene product, were also found in the 5′ flanking region of the postulated putP gene. A typical p-independent transcription termination signal was found after the terminator codon of the putP gene.
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    URL: http://dx.doi.org/10.1007/BF00330424
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  • 19
    Electronic Resource
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    Amino acid alterations in a hydrophobic region of the TraT protein of R6-5 increase the outer membrane permeability of enteric bacteria (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 178-180 
    Details
    ISSN: 1617-4623
    Keywords: Outer membrane permeability ; Outer membrane proteins ; TraT protein ; Escherichia coli ; Salmonella typhimurium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two insertion mutations, each introducing a new negatively charged amino acid residue into a hydrophobic region of the TraT protein coded by the F-like plasmid R6-5 caused significant alterations in outer membrane permeability of Escherichia coli and Salmonella typhimurium, so that strains carrying plasmids with either of these mutations became sensitive to hydrophobic antibiotics.
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    URL: http://dx.doi.org/10.1007/BF00337776
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  • 20
    Electronic Resource
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    A newly discovered tRNA 1 Asp gene (aspV) of Escherichia coli K12 (1987)
    Springer
    Molecular genetics and genomics 206 (1987), S. 356-357 
    Details
    ISSN: 1617-4623
    Keywords: tRNA 1 Asp ; aspV ; Escherichia coli ; dnaQ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report a new tRNA 1 Asp gene near the dnaQ gene, which is located at 5 min on the Escherichia coli linkage map. We named it aspV. The sequence corresponding to the mature tRNA is identical with that of the two previously identified tRNA 1 Asp genes (aspT and aspU), but there is no homology in the sequences of their 3′-and 5′-flanking regions.
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    URL: http://dx.doi.org/10.1007/BF00333595
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  • 21
    Electronic Resource
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    Cloning and expression of the exbB gene of Escherichia coli K-12 (1987)
    Springer
    Molecular genetics and genomics 206 (1987), S. 246-251 
    Details
    ISSN: 1617-4623
    Keywords: Iron transport ; Escherichia coli ; exbB gene ; Colicin uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The exbB locus of Escherichia coli is involved in the uptake of certain iron(III) siderophore compounds, of vitamin B12 and of certain colicins. Outer membrane receptor proteins are essential constituents of the corresponding uptake systems. The DNA carrying the exbB locus was cloned into pACYC184 and subcloned into pUC18. With the use of insertion mutagenesis employing transposon Tn1000 and by deletion analysis, the exbB locus was confined to a 1.9 kb DNA fragment. An in vitro transcription/translation system and minicells programmed by exbB + plasmids expressed a protein with an apparent molecular weight of 26,000. One plasmid, designated pKE7, expressed this protein to an extent that it became a prominent band in the membrane fraction of transformants. In contrast, chromosomally encoded ExbB protein could not be detected. The plasmid-encoded ExbB protein was mainly localized in the cytoplasmic membrane. Ferrichrome transport in exbB mutants was restored by exbB + plasmids. Moderate overexpression of ExbB resulted in an enhanced ferrichrome transport, strong overexpression reduced the transport rate compared to a wild-type strain. The ExbB function shares some properties with the TonB function.
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    URL: http://dx.doi.org/10.1007/BF00333580
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  • 22
    Electronic Resource
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    Effect of the direction of DNA replication on mutagenesis by N-methyl-N′-nitro-N-nitrosoguanidine in adapted cells of Escherichia coli (1987)
    Springer
    Molecular genetics and genomics 208 (1987), S. 446-449 
    Details
    ISSN: 1617-4623
    Keywords: N-methyl-N′-nitro-N-nitrosoguanidine ; Mutagenesis ; Lambda phage ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The methylating agent N-methyl-N′-nitro-N-nitrosoguanidine preferentially induces G:C to A:T transitions at DNA base pairs with the G in one particular strand of the cI gene in a lambda prophage, in this case the non-transcribed straind, in Escherichia coli cells in which the adaptive response is induced. The same preference is found for the cI gene inserted in the genome in the inverse orientation, so the differential effect is not caused by the direction of motion of the DNA replicating fork.
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    URL: http://dx.doi.org/10.1007/BF00328137
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  • 23
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    Cloning and sequencing of the HU-2 gene of Escherichia coli (1987)
    Springer
    Molecular genetics and genomics 209 (1987), S. 408-410 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; HU-2 protein ; Gene cloning ; Nucleotide sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Escherichia coli HU-2 gene was cloned using a DNA fragment from the HU-1 gene as a probe. The amino acid sequence of the HU-2 protein deduced from the nucleotide sequence is in good agreement with the published sequence. The nucleotide sequence has a possible promoter and a typical ribosomal binding site upstream of the translation initiation codon (AUG) and a possible rhoindependent terminater site downstream of the termination codon (UAA) of the gene.
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    RNA polymerase sigma-related proteins in Escherichia coli: Detection by antibodies against a synthetic peptide (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 5-9 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; RNA polymerase ; Sigma factor ; Heat-shock ; Synthetic peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Antibodies were raised against a synthetic tetradecameric peptide with an amino acid sequence, DLIQEGNIGLMKAV, which corresponds to the most highly conserved region of bacterial RNA polymerase σ factors. In a Western-blot analysis of total Escherichia coli proteins, the antiserum reacted specifically with at least three proteins with apparent molecular weights of 75 kDa, 27 kDa and 23 kDa, in addition to the known σ factors (σ70 and σ32). The majorities of σ70 and σ32 were recovered as associated forms with the RNA polymerase on glycerol gradient centrifugation, while the other cross-reacting proteins were not. Unambiguous evidence was obtained which indicated that the intracellular level of σ32 increased rapidly upon heatshock, at least in the strain containing high copy numbers of the rpoH gene.
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    Secondary structure of the autoregulatory mRNA binding site of ribosomal protein L1 (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 60-68 
    Details
    ISSN: 1617-4623
    Keywords: mRNA secondary structure ; Nuclease sensitivity ; Translational repressor ; Ribosomal protein ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The secondary structure of the autoregulatory mRNA binding site of Escherichia coli ribosomal protein L1 has been studies using enzymatic methods. The control region of the E. coli L11 operon was cloned into a vector under control of the Salmonella phage SP6 promoter, and RNA transcribed using SP6 RNA polymerase. The secondary structure of this RNA was probed using structure-specific nucleases, and by comparison of the data with computer predictions of RNA folding, secondary structural features were deduced. The proposed model is consistent with elements of some previously proposed models, but differs in other features. Finally, secondary structure information was obtained from two mutant mRNAs and the structural features correlated with observed phenotypes of the mutants.
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    Nucleotide sequence of putC, the regulatory region for the put regulon of Escherichia coli K12 (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 364-368 
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    ISSN: 1617-4623
    Keywords: Promoter region of the putA gene ; putC ; Nucleotide sequence ; Escherichia coli ; nitrogen control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of the putC region, from which divergent transcription of the putP and putA genes starts, was determined. The promoter region for the putA gene was restricted to the location between the HindIII site and the NcoI site or at the NcoI site by using putA-lacZ fusion plasmids and the transcriptional start for the putA gene was identified in the region between the HindIII site and the NcoI site by S1 mapping. This region also contains a potential CAP binding site, a ribosome binding site, and a sequence that is highly homologous to argTr. five potential promoters (putPp1-putPp5) for the putP gene, which were separate from the promoter region for the putA gene, were indicated by S1 mapping analysis of the putP gene transcripts. We concluded that the putC region is 419 bp long and contains two independent sets of promoters, regulating the expression of putP and putA genes in opposite directions. In addition, this region was found to contain an open reading frame (orf) capable of encoding a polypeptide of 111 amino acids in overlapping fashion. But studies using an orf-lacZ fusion gene showed that this open reading frame was not expressed.
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    An efficient procedure for extraction and determination of steroids in the tissue of laboratory animals (1987)
    Springer
    Chromatographia 23 (1987), S. 796-802 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Steroids ; Rat tissue ; Purification by extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatographic method for analysis of steroids in the tissue of laboratory animals is described. A two-stage solid extraction procedure, utilizing Sep-pak C18 and graphitized carbon black, gives a purified product. Steroids in this extract were separated by multistep gradient elution with a reversedphase liquid chromatography system, using acetonitrilewater as solvent. Several columns with different geometry and phase loading were investigated. Optimum resolution was obtained with a medium covered and spherical particle. The applicability of this method was successfully demonstrated in the analysis of the testis and adrenal gland of rat.
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    HPLC of aminoacids on silica coated with ammonium tungstophosphate (1987)
    Springer
    Chromatographia 23 (1987), S. 814-817 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin layer chromatography ; Ammonium tungstophosphate ; Aminoacids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of aminoacids on columns of silica coated with different percentages of ammonium tungstophosphate at several buffer phosphate concentrations is reported. The stationary phase shows a high selectivity towards aminobutyric acids and methyl derivatives of tryptophan due to the distance between the carboxylic group and the −NH 3 + group involved in the cation-exchange process and/or to the steric hindrance by a methyl substituent. A relationship between HPLC and HPTLC data has been verified and applied to the prediction of the separation of six aminoacids.
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    Limits of determination and calibration in HPLC (1987)
    Springer
    Chromatographia 23 (1987), S. 934-938 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Calibration ; Confidence interval ; Limit of determination ; Limit of calibration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In HPLC calibration the expressions lowest calibration limit and determination limit are defined in statistical terms. The lowest calibration limit is the minimum mass in the measured series of calibration points. It is calculated from the confidence interval of the inverse of the calibration function as the lowest mass limit that may be differentiated from zero mass with a preset probability of error. If the calculated lowest calibration limit is lower than the actual data, points at lower concentration may be measured. The determination limit is the smallest concentration of an analysis that is differentiated from the concentration zero or an apparent blind value in the calibration curve with a given probability of error. Using two different UV-detectors (variable wavelength and photodiode-array) the lowest calibration limit is experimentally evaluated and compared with specific data for the detectors.
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    Sub-nanogram detection of dihydroartemisinin after chemical derivatization with diacetyldihydrofluorescein followed by high-performance liquid chromatography and UV absorption (1987)
    Springer
    Chromatographia 23 (1987), S. 112-114 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pre-column derivatization ; Ultraviolet detector sensitivity ; Dihydroartemisinin ; Diacetyldihydrofluorescein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of diacetyldihydrofluorescein (DADF) for derivatization of dihydroartemisinin (dihydroqinghaosu, DHQHS) is proposed. The reaction between DHQHS and this reagent in the presence of 4-dimethylaminopyridine (DMAP) and N,N′-dicyclohexylcarbodiimide (DCC) was complete in 8 hours at room temperature giving about 80 per cent theoretical yield. The derivative showed intense UV absorption, thus providing a sensitivity of 0.1 nanogram by UV detection after column separation. The influences of the ratio of the reagents, reaction temperature, chromatographic conditions and the extent of detection linearity were investigated. The reaction gave consistent results and chromatographic separation was not affected by an excess of the reagent or side products.
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    HPLC in photokinetics: Determination of reaction mechanism and photochemical quantum yields of (E)-1-phenylpropene (1987)
    Springer
    Chromatographia 23 (1987), S. 395-400 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Photokinetic data ; Reaction mechanism ; (E)-1-phenylpropene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A combined method of high-performance liquid chromatography and UV-absorption spectroscopy is described for use in dynamic systems. It provides a way of obtaining detailed mechanistic information as well as quantitative data (rate constants, quantum yields), even though neither mechanism nor photoproducts are known. The kinetic treatment of the photoreaction of (E)-1-phenylpropene was successful, showing a photo-isomerization and a parallel step. Information on this additional step is obtained by using HPLC to observe the changes in the concentrations of the reactants' selectivity. The necessity of process control is demonstrated.
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    Determination of particulate fatty acids as P-bromophenacyl- or phenylphenacylesters using HPLC (1987)
    Springer
    Chromatographia 23 (1987), S. 419-422 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fatty acid esters ; Particulate material in seawater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the determination of fatty acids of the molecular weight range of propionic to erucic acid is reported. The acids are converted to either p-bromophenacyl-or p-phenylphenacylesters and the esters are separated by HPLC and detected by UV-absorption. Twentytwo esters, including saturated, monoolefinic and polyunsaturated ones were separated within one HPLC-run. The detection limit is about 5 pmol per fatty acid. The application of the method to particulate material is described.
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    New polymer coated anion-exchange HPLC-phases: Immobilization of poly (2-hydroxy, 3N-ethylenediamino) butadiene on silica and alumina (1987)
    Springer
    Chromatographia 23 (1987), S. 435-441 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange stationary phases ; Polymer coating ; Cross-linking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary PHEB=POLY(2-hydroxy, 3N-ethylenediamino)butadiene has been synthesized. This unsaturated pre-polymer can be immobilized on different, preferably inorganic supports of suitable porosity such as silica or alumina by cross-linking. Weak anion-exchange phase are obtained. Such phases do not have the disadvantages of organic polymeric phases, regarding pressure stability and swelling by solvent influence. The ion-exchange capacity and the retentivity of IE-separations can deliberately be varied via the thickness of the cross-linked polymer layer. Alumina can also be coated with PHEB applying the same cross-linking procedure. Such phases exhibit an exceptional chemical stability even when operated with mobile phases at very high pH-values. Separations of excellent selectivity are achieved for inorganic anions, as well as with mixtures of aliphatic and aromatic free acids also including hydroxy- (mono- or poly)carboxylic acids.
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    Application of the electrostatic interaction concept for the study of the retention behaviour of peropyrene-type polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 473-476 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase systems ; Stationary phase-solute interactions ; Polycyclic aromatics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capacity factors of peropyrene-type polycyclic aromatic hydrocarbons were measured using 15 different liquid chromatographic reversed phase systems. On the basis of the retention data the electric interaction indices have been calculated. Application of these indices for structure-retention studies on peropyrene-type polycyclic aromatic hydrocarbons is demonstrated.
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    Separation of gonadal steroid epimers using high performance liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 31-32 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gonadal steroids ; Epimers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chromatographic separation of biologically active epimeric steroids was carried out using a combination of normal and reversed phases. Testosterone (17β-OH) was separated from its 17α-OH epimer epitestosterone using a normal phase silica column whereas their reduced 5α-metabolites were separated on a reversed phase system. The separation of other gonadal steroids including the epimers 20α- and 20β-hydroxypregn-4-en-3-one is also discussed. The technique is particularly useful for separating mixtures of naturally occurring steroid epimers prior to radioimmunoassay.
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    Separation of chlorophylls and their degradation products in marine phytoplankton by reversed-phase high-performance liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 26-30 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ammonium acetate buffer eluent ; Chlorophylls and degradation products ; Marine phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An RP-HPLC procedure which separates chlorophylls and their degradation products is described. By employing an amonium acetate buffered mobile phase and a linear gradient elution, complex mixtures of chloroand phaeopigments are separated in less than 30 minutes. The method has been applied to the control of chlorophyll enzymatic degradation in cultures of two algal species, and has also been successfully used in the analysis of algal xanthophylls.
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    Reversed-phase HPLC behaviour of metal complexes with 4-(2-pyridylazo) resorcinol. A detailed study in the light of solvophobic theory (1987)
    Springer
    Chromatographia 23 (1987), S. 736-746 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Behaviour of metal complexes ; Solvophobic theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of Cu(II), Fe(II), Ni(II) and Co(II) complexes with 4-(2-pyridylazo)resorcinol was studied. The experimental results were very sensitive even to less obvious operational parameters like the kind of the cation (sodium or ammonium) of the phosphate salt used as buffer. The puzzling pattern of the data obtained was interpreted in terms of the equations formulated by Horvath's ‘olvophobic” theory which correlates the capacity factors of the solutes with the surface tension of the mobile phase. A satisfactory rationalization of the data was obtained together with qualitative information on the stoichiometry and charge state of metal complexes. Useful suggestions about the direction to address the experimental work in order to obtain the best results was also obtained.
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    Separation of transition metal ions and preconcentration of platinum (IV) and chromium (III) on alumina-immobilized diethylenetriaminepentaacetic acid by ligand exchange (1987)
    Springer
    Chromatographia 23 (1987), S. 747-751 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand Exchange ; Diethylenetriaminepentaacetic acid ; Transition metal ion separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Basic alumina-bonded diethylenetriaminepentaacetic acid (DTPA) has been utilized for the separation and preconcentration of some transition metal ions on the basis of ligand exchange. Breakthrough capacity and rate of sorption have been studied. The distribution coefficients of 16 transition metal ions have been determined in demineralized water, 0.01 M sodium citrate and in four different pH systems. On the basis of differences in Kd values some quantitative separations of metal ions have been achieved. The greater selectivity behaviour (higher Kd values) of the adsorbent for Pt(IV)and Cr(III) has been utilized for their preconcentration in the presence of other metal ions. The method has been employed for the recovery of Pt(IV) and Cr(III) from tapwater and sea-water samples.
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    Gel filtration and high-performance liquid chromatographic analysis of phosphotungstic acid soluble peptides from blue cheeses (1987)
    Springer
    Chromatographia 23 (1987), S. 764-766 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gel permeation chromatography ; Cheese peptides ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The nitrogen fraction from cheese, soluble in phosphotungstic acid has been analyzed by gel permeation and high performance liquid chromatography. Elution profiles of this fraction on Sephadex G-10 show that there are no peptides of molecular weight higher than 700 daltons. Six fractions have been obtained. The first one has the peptides and some amino acids. Fractions II to VI contains mostly free amino acids. Fraction I has been separated into many peaks by HPLC. Six or seven of these peaks are presumed to correspond to peptides.
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    Preparation and performances of small bore columns packed with reversed-phase materials and their use for the evaluation of air pollutants (1987)
    Springer
    Chromatographia 23 (1987), S. 803-810 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Small-bore packed columns ; Air pollutants ; PAH, nitro and oxy-PAH ; Aldehydes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of small bore columns (1 mm i.d.) packed with reversed-phase materials is described. High efficiency (Hmin=2 dp), coupled with a small C term (0.005 sec) have been obtained so that high speed can be combined with sufficient resolution for the separation of complex organic mixtures. These columns have been used for the separation of air pollutants dispersed in different matrices (air, particulate matter and rain water). Practical applications include the determination of aldehydes in air and emission samples, PAHs, nitrated and oxygenated PAHs in dust sampled from the stack of an industrial emission or collected in a urban area and the analysis of organic components dissolved in rain water collected at a rural site. Specific detection of these pollutants has been achieved by connecting small bore columns to UV absorbance, voltammetric and fluorimetric detectors. Mass spectra of some specific components have been recorded using the off-line technique.
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    HPLC determination of the aromatic fraction of gasoline (1987)
    Springer
    Chromatographia 23 (1987), S. 825-828 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gasoline ; Single-ring aromatic hydrocarbons ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This work reports a rapid and easy procedure for the analysis of the aromatic fraction in gasoline. No sample pretreatment is required, since the gasoline is diluted in methanol and directly injected into a liquid chromatograph. A spectrophotometer detector and a spectrofluorimeter detector are used in series. The procedure has been applied to a large number of Italian and European refined gasoline samples.
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    Separation of aldicarb, aldicarb sulfoxide, and aldicarb sulfone on unmodified silica with reverse-phase eluents (1987)
    Springer
    Chromatographia 23 (1987), S. 109-111 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Normal and reverse phase ; Aldicarb ; Aldicarb sulfoxide ; Aldicarb sulfone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Aldicarb, aldicarb sulfoxide, and aldicarb sulfone were chromatographed on an octyl-silica bonded-phase column and on an unmodified silica column using acetonitrile/water mobile phases. The elution order of the analytes from the silica column was different from that using the octyl-silica bonded phase and allowed confirmation of residues of aldicarb sulfoxide in citrus nectar. Isocratic elution of the unmodified silica column allowed rapid sample throughput.
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    High-performance ligand exchange chromatography on chiral diamine-bonded silica gel (1987)
    Springer
    Chromatographia 23 (1987), S. 118-120 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand-exchange chromatography ; Chiral bonded phase ; Racemate resolution ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The resolution of racemates on chiral chemically bonded silica gel by high-performance ligand-exchange chromatography is described. The stationary phase was prepared by bonding (−) trans 1,2 cyclohexanediamine to silica gel through the coupling agent 3-glycidoxypropyl silane. The resolution of several α-amino acids and of compounds of pharmaceutical interest is reported.
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    Characteristics of the B subunit of the thermolabile enterotoxin produced byEscherichia coli strain A−B+ (1987)
    Springer
    Bulletin of experimental biology and medicine 103 (1987), S. 94-97 
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    ISSN: 1573-8221
    Keywords: Escherichia coli ; B subunit ; diarrhea ; antibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1007/BF00840150
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    Functional properties ofEscherichia coli single-stranded DNA binding proteins in vivo (1987)
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    Bulletin of experimental biology and medicine 103 (1987), S. 372-374 
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    ISSN: 1573-8221
    Keywords: Escherichia coli ; SSB proteins ; mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1007/BF00840566
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    Large non-homology in heteroduplex DNA is processed differently than single base pair mismatches (1987)
    Springer
    Molecular genetics and genomics 206 (1987), S. 181-184 
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    ISSN: 1617-4623
    Keywords: Escherichia coli ; Bacteriophage λ ; DNA loops ; DNA repair ; Gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Unmethylated DNA heteroduplexes with a large single stranded loop in one strand have been prepared from separated strands of DNA from two different strains of bacteriophage λ, one of which has a ∼800 base pair IS1 insertion in the cI gene. The results of transfections with these heteroduplexes into wild-type and mismatch repair deficient bacteria indicate that such large non-homologies are not repaired by the Escherichia coli mismatch repair system. However, the results do suggest that some process can act to repair such large non-homologies in heteroduplex DNA. Transfections of a series of recombination and excision repair deficient mutants suggest that known excision or recombination repair systems of E. coli are not responsible for the repair. Repair of large non-homologies may play a role in gene conversion involving large insertion or deletion mutations.
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    Molecular cloning and nucleotide sequence of the mutT mutator of Escherichia coli that causes A:T to C:G transversion (1987)
    Springer
    Molecular genetics and genomics 206 (1987), S. 9-16 
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    ISSN: 1617-4623
    Keywords: mutT mutator ; Escherichia coli ; A:T→C:G transversion ; Molecular cloning ; Nucleotide sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Escherichia coli mutator gene mutT, which causes A:T→C:G transversion, was cloned in pBR 322. mutT + plasmids carry a 0.9 kb PvuII DNA fragment derived from the E. coli chromosome. Specific labelling of plasmid-encoded proteins by the maxicell method revealed that mutT codes for a polypeptide of about 15,000 daltons. The protein was overproduced when the mutT gene was placed under the control of the lac regulatory region on a multicopy runaway plasmid. The nucleotide sequence of the mutT gene was determined by the dideoxy method.
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    Expression of F transfer functions depends on the Escherichia coli integration host factor (1987)
    Springer
    Molecular genetics and genomics 207 (1987), S. 302-305 
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    ISSN: 1617-4623
    Keywords: Escherichia coli ; IHF protein ; Plasmid F ; Conjugal transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We present evidence that the Escherichia coli DNA binding protein, IHF, plays an important role in conjugal transfer of the plasmid F. Our results suggest that IHF exerts this effect by positively effecting transcription of the transfer (tra) operon of the plasmid.
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    Nucleotide sequence of the fhuC and fhuD genes involved in iron (III) hydroxamate transport: Domains in FhuC homologous to ATP-binding proteins (1987)
    Springer
    Molecular genetics and genomics 209 (1987), S. 49-55 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Iron hydroxamate transport ; fhuC, fhuD genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The transport of Fe3+ into cells of Escherichia coli occurs via siderophores and the uptake through the outer membrane of three Fe3+-siderophore compounds containing hydroxamate residues requires three specific receptor proteins. In contrast, transport through the cytoplasmic membrane is catalysed by three common proteins encoded by the fhuB, fhuC and fhuD genes. The nucleotide sequence of a DNA fragment containing the fhuC and fhuD genes has been determined: the open reading frame of fhuC contains 795 nucleotides which encode a polypeptide with a molecular weight of 29 255 and the largest open reading frame of the fhuD region comprises 888 nucleotides. However, we propose that translation of fhuD initiates at the fourth potential start codon resulting in a polypeptide with a molecular weight of 28 282. Both proteins are moderately nonpolar and membrane-bound. They lack obvious signal sequences. Segments of the FhuC protein display strong homology to ATP-binding proteins, suggesting a function in Fe3+ uptake similar to the ATP-binding proteins of transport systems that depend on periplasmic proteins. This study completes the nucleotide sequence of the fhu operon which consists of the four genes fhuA fhuC fhuD fhuB arranged in this order on the E. coli chromosome and transcribed from fhuA to fhuB.
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    URL: http://dx.doi.org/10.1007/BF00329835
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    The relative rate of synthesis and levels of single-stranded DNA binding protein during induction of SOS repair in Escherichia coli (1987)
    Springer
    Molecular genetics and genomics 209 (1987), S. 612-614 
    Details
    ISSN: 1617-4623
    Keywords: ssb ; Single-stranded DNA binding protein ; SOS repair ; RecA protein ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Induction of the SOS response in Escherichia coli results in an increase in the relative rate of synthesis of single-stranded DNA binding protein (SSB). In contrast to RecA protein, this increase is slow and does not lead to higher SSB levels. The significance of ssb induction to SOS repair is discussed.
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    URL: http://dx.doi.org/10.1007/BF00331171
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    Hierarchy of the strength of Escherichia coli stringent control signals (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 1-4 
    Details
    ISSN: 1617-4623
    Keywords: Stringent control ; RNA polymerase ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The quantitative effect of ppGpp, the effector of stringent control, on various Escherichia coli promoters was measured in an in vitro mixed transcription system. This allowed us to determine, among these promoters, the hierarchy of promoters according to their ppGpp susceptibility. The strength of the stringent control signal, however, was found to be altered when the test promoters were transcribed by ppGpp-insensitive RNA polymerases from relaxed mutants of E. coli, which carry substitutions in the β subunit gene (rpoB). Thus, it was concluded that the activity of the stringent control signal depends on the nature of the RNA polymerase as well as that of the promoter.
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    URL: http://dx.doi.org/10.1007/BF00337750
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    Replication intermediate of a hybrid plasmid carrying the replication terminus (ter) site of R6K as revealed by agarose gel electrophoresis (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 394-398 
    Details
    ISSN: 1617-4623
    Keywords: Replication terminus ; Escherichia coli ; Y-shaped molecule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 4.32 kb DNA fragment, on which the DNA replication terminus (terR) site of plasmid R 6K was located, was inserted into the unique EcoRI site of plasmid pUC9. To detect replication intermediate molecules with a replication fork halted at the terR site, a cell DNA extract was digested with EcoRI, electrophoresed through an agarose gel and stained with ethidium bromide. In addition to two major bands, one derived from vector DNA and the other from the ter insert fragment, two extra minor bands were detected. Following DNA-DNA hybridization and electron microscopic observation we concluded that the two minor bands corresponded to the two Y-shaped molecules, produced from the θ-shaped intermediate molecules by EcoRI digestion.
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    URL: http://dx.doi.org/10.1007/BF00327188
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    Escherichia coli strains with defined mutations which alter cellular permeability (1987)
    Springer
    Journal of industrial microbiology and biotechnology 1 (1987), S. 335-340 
    Details
    ISSN: 1476-5535
    Keywords: Escherichia coli ; Outer membrane permeability ; Porin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary We describe the construction and analysis of an isogenic series ofEscherichia coli K12 strains that vary in their outer membrane permeability. They carry mutations that alter the amount and the type of porin present in the outer membrane. The permeability profiles of these strains suggest that both the amount and the type of porin present in the outer membrane affects permeability. Several of the strains carry mutations that extend the permeability of the outer membrane to include a variety of compounds that are normally excluded from entering the cell.
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    URL: http://dx.doi.org/10.1007/BF01569312
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    High-cell-density fermentation studies of a recombinantE. coli that expresses atrial natriuretic factor (1987)
    Springer
    Journal of industrial microbiology and biotechnology 2 (1987), S. 47-52 
    Details
    ISSN: 1476-5535
    Keywords: Fermentation ; High cell density ; Escherichia coli ; RecombinantE. coli ; Atrial natriuretic factor (ANF) ; Fusion protein expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Studies are presented on the fermentation of recombinantEscherichia coli that express rat atrial natriuretic factor (ANF) as a fusion protein. Our objective was to achieve high cell density while maintaining ANF expression at the same level as observed in shake flasks. Improved fermentation conditions included: maintaining glucose concentrations at 1 g/l, using an enriched medium, adding concentrates of medium throughout the fermentation, and blending oxygen for adequate aeration. Cell densities of 12 g/l (dry weight) were achieved, which represented a 10-fold increase over non-improved conditions, while maintaining ANF levels at 7 mg/g of dry cell mass. When galactose was used as an initial carbon source or as a feed supplement, there was a 2-3-fold increase in the expression of ANF from these high-cell-density fermentations. The recombinant ANF was biologically active.
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    URL: http://dx.doi.org/10.1007/BF01569405
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    Effects of fermentation feeding strategies prior to induction of expression of a recombinant malaria antigen inEscherichia coli (1987)
    Springer
    Journal of industrial microbiology and biotechnology 2 (1987), S. 87-95 
    Details
    ISSN: 1476-5535
    Keywords: Fermentation ; Process control ; Expression of recombinant proteins ; Escherichia coli ; Malaria vaccine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A variety of feeding strategies have been described for attaining high cell densities in fed-batch fermentors. Although cell density is an important component in the produtivity of recombinant fermentations, it must be achievable with high product expression levels. Experiments were conducted to study the influence of fermentation feeding strategies on the production of a recombinant malaria antigen inEscherichia coli. C-source feeding profiles were calculated to maintain specific growth rates at 0.1, 0.2, 0.35, and 0.5 l/h prior to induction in defined and complex media using an exponential growth model. Fed-batch fermentations employing these feeding profiles effectively controlled the specific growth rates prior to induction. Antigen yields per dry cell weight did not vary with specific growth rate. Antigen yields from fed-batch fermentations achieving high cell densities were similar to batch fermentations achieving low cell densities. These results show that C-feeding policies can limit growth without reducing expression levels in some systems, and suggest applications in managing oxygen demand and catabolic by-product formation during process scale-up.
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    URL: http://dx.doi.org/10.1007/BF01569507
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    Effect of rare earth cations on bactericidal activity of anionic surfactants (1987)
    Springer
    Journal of industrial microbiology and biotechnology 1 (1987), S. 377-381 
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    ISSN: 1476-5535
    Keywords: Antimicrobial ; Metal salt ; Lanthanum ; Escherichia coli ; Staphylococcus aureus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Rare earth metal cations are antibacterially synergistic with anionic surfactants, yielding mixtures that have bactericidal activity against a variety of gram-positive and gram-negative bacteria at minimum concentrations ranging from 16 to 125 μg/ml. Uptake of surfactant byEscherichia coli increases in the presence of lanthanum, suggesting that the role of rare earth metal cations is to reduce the net negative surface charge on the bacteria, thereby increasing the affinity between the negatively charged surfactant and the bacterial surface.
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    URL: http://dx.doi.org/10.1007/BF01569335
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    Optimization of fat soluble vitamin separation in reversed-phase microcolumn liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 320-324 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore capillary columns ; Polymer based octadecylsilica bonded phase ; Fat soluble vitamins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Separation behavior of fat soluble vitamins on various chemically bonded materials in non-aqueous reversedphases microcolumn liquid chromatography has been investigated. The best performance was found on a polymer-based octadecyl bonded phase. Optimization of separation for vitamins D2, D3, E and E acetate has been tried using this polymer-based column and it has been found that a binary mobile phase consisting of acetonitrile and methanol gave complete separation of fat soluble vitamins.
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    URL: http://dx.doi.org/10.1007/BF02316175
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    A comparative study of large volume injection techniques for microbore columns in HPLC (1987)
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    Chromatographia 23 (1987), S. 331-336 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore columns ; Injection techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper focuses attention on the potentially larger signal-to-noise ratios produced by microbore columns in comparison with conventional columns. The increased chromatographic signals by the application of microbore columns are due to the lower chromatographic dilution of elution profiles which are proportional to the square of the column inner radius. Generally less than 1μl sample should be injected into microbore systems to obtain the full benefit of the column performance. However, since more sample can be loaded on conventional columns compared to microbore columns the advantage of improved signal-to-noise ratio can only be realised in situations where very little sample is available. To inject more than 1μl sample, at the same time avoiding extra band-broadening effects, suitable injection techniques must be available. In this study three injection methods for microbore systems that meet this condition, are studied and compared.
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    URL: http://dx.doi.org/10.1007/BF02316178
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    High-performance liquid chromatography using a color-forming agent as a component of the mobile phase. Separation and determination of nickel and zinc wity xylenol orange (1987)
    Springer
    Chromatographia 23 (1987), S. 355-360 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange chromatography ; Xylenol orange ; Separation of nickel and zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid chromatographic procedure for separating nickel and zinc has been developed. Xylenol orange, which is one of the sensitive and commercially available color-forming agents, was used as a component of the mobile phase. The two ions could be separated on weak anion-exchange gels within 10 min. The procedure was suitable for the determination of nickel and zinc in relatively pure solutions with fairly high sensitivity. The described liquid chromatographic analysis would be also potentially applicable for any aqueous sample containing trace levels of metal cations at 1–10 ppm.
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    URL: http://dx.doi.org/10.1007/BF02316182
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    Determination of oligosaccharides (DP1-DP8) in samples with high content of salt and organic matter by reversed phase HPLC (1987)
    Springer
    Chromatographia 23 (1987), S. 557-560 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Oligosaccharides ; Interference by salts ; Complex biological samples ; Enzymatic assays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the determination of oligosaccharides in samples of high salt content by RP-HPLC with water as eluent and refractive index detection. The samples, mussel processing wastes which are used as media for microfungus and yeast cultures and hence for enzymatic assays (amilolitic capacity) of these microorganisms that develop within the wastes, have been treated with ethanol to precipitate the macromolecular organic matter and desalted by a modified mixed bed resin before chromatographic analysis is carried out.
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    URL: http://dx.doi.org/10.1007/BF02324863
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    Group-type separation and determination of phenolic compounds in coal-derived products by HPLC (1987)
    Springer
    Chromatographia 23 (1987), S. 579-582 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Backflush technique ; Coal-derived procucts ; Separation of phenolic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid method was developed for the direct extraction of phenolic compounds from coal-derived products and subsequent isocratic HPLC analysis in a reversed-phase system by using the backflush technique.
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    High-performance liquid chromatography using a color-forming agent as a mobile phase component. Separation of alkaline-earth-metal cations with arsenazo III and a non-porous gel column (1987)
    Springer
    Chromatographia 23 (1987), S. 583-589 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Non-porous gel ; Alkaline-earth cations ; Arsenazo III
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid chromatographic procedure for separating alkaline-earth-metal cations with a non-porous gel column has been developed. Arsenazo III, which is one of the sensitive and commercially available color-forming agents, was used as a component of the mobile phase. Magnesium and calcium could be separated on the nonporous gel column within 55 seconds. The procedure was suitable for the separation of alkaline-earth-metal cations in relatively pure solutions with high sensitivity. Because of its rapidity the described procedure is also potentially applicable for any aqueous sample.
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    High-performance liquid chromatography of biphenols and bis (hydroxyphenyl) propanes (dianes) with voltammetric and UV photometric detection (1987)
    Springer
    Chromatographia 23 (1987), S. 102-108 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Biphenols ; Dihydroxyphenylpropanes ; Voltammetric detection ; UV photometric detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behaviour of mono- and dihydroxy derivatives of biphenol and bis(hydroxyphenyl)propanes was studied on chemically bonded C-18, CN-, phenyl, phenoxypropyl- and NH2 stationary phases and on silica gel. The effects of the mobile phase, i.e., of the methanol content, the ionic strength, pH and the contents of cationic and anionic ion-pairing agents on the retention data were investigated. In the reversed-phase systems, all the substances are satisfactorily separated except for 3- and 4-hydroxybiphenyl; these isomers can be separated on silica gel, using a mixture of heptane and propanol as the mobile phase. Sodium dodecylsulphate, present at concentrations higher than the critical micelle concentration (about 10−2 M, depending on the methanol content), causes a decrease in the retention times and an improvement in the separation. UV absorption spectra, calibration curves and the detection limit values were obtained at two wavelengths and at various salt concentrations in the mobile phase. Hydrodynamic voltammograms of the solutes were measured in a carbon fibre detector and the calibration curves and detection limit values were measured at the optimal voltage (+1.2 V/Ag/AgCl) as a function of the mobile phase composition. For most test substances voltammetric detection is two to three times more sensitive than UV detection. The combination of a UV and a voltammetric detector in series has been utilized to identify the products of microbial degradation of biphenyl.
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    Reversed-phase ion-pair systems to predict partition coefficients of β-carbolines by HPLC and TLC (1987)
    Springer
    Chromatographia 23 (1987), S. 713-716 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Ion pairing system ; Log P prediction ; Group contributions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A group of 17 β-carbolines was studied in HPLC and TLC systems in order to predict their partition coefficients (log P values). On account of the basic or acid character of some of these compounds, an ion pairing system gave the best results. Both HPLC and TLC data were comparable for log P prediction but severe pH conditions required the use of TLC plates. Retention data are quantitatively related to lipophilicity (expressed as the Hansch constant) and polarity (as the inductive constant) of the solute molecule.
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    URL: http://dx.doi.org/10.1007/BF02312661
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    Chitosan-coated silica gel as a new support in high-performance liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 731-735 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chitosan-coated silica gel ; Nucleotides ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new stationary phase was prepared by immobilizing the chitosan, a natural hydrophilic polymer, on microparticolate silica gel. The effect of the polarity, pH and ionic strength of the mobile phase has been studied in order to find optimal conditions for the separation of nucleotides and aminoacids. The influence of the properties of the mobile phase on the retention was examined, allowing to employ the chitosan-coated silica gel both to anion exchange and adsorption, depending on the pH and the polarity of the eluent used.
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    Qualitative description of dispersive and inductive electrostatic interactions in reversed-phase liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 752-759 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase systems ; Phases-solute interactions ; Molecular polarizability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Variations in the electrostatic interaction have been studied using polycyclic aromatic hydrocarbons as standard compounds and different reversed-phase HPLC systems. Various methanol-water and acetonitrile-water binary mixtures were applied as the mobile phase. The stationary phases investigated consist of octadecylsilica and arenyl-silica. Using polarizability, dipole moment and ionization potential values of the solutes and mobile phase components as molecular descriptors an electrostatic interaction model is proposed.
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    Ligand exchange separation of amines on copper (II) sorbed on zinc silicate (1987)
    Springer
    Chromatographia 23 (1987), S. 93-96 
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    ISSN: 1612-1112
    Keywords: Paper chromatrography ; Column liquid chromatography ; Copper-impregnated zinc silicate ; Separation of amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Papers impregnated with Cu(II) sorbed on zinc silicate have been used to study the ligand exchange chromatographic behavior of amines. RF values of 16 amines have been studied in 6 different systems. On the basis of differences in RF values various analytically important qualitative separations of amines on impregnated papers and quantitative separations on columns of copper(II) sorbed on zinc silicate have been achieved.
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    Comparison of octadecyl-bonded silica and styrene-divinylbenzene copolymer sorbents for trace enrichment purposes fundamental aspects II. Linear chromatographic behaviour of the extracting supports (1987)
    Springer
    Chromatographia 23 (1987), S. 163-168 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Linear isotherms ; Octadecyl bonded silica ; Styrene divinylbenzene ; Frontal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two reversed-phase LC systems were investigated by frontal analysis for the determination of linear chromatographic conditions, as defined according to the isotherm concept. The Partisil ODS-3 bonded silica and the PRP-1 polystyrene-divinylbenzene resin were used as stationary phases together withtrans-2-hexen-al as test solute and methanol-water mixtures as mobile phases. Particular attention was paid to the respective influence of the two main parameters which may cause sorbent overloading, that is, the capacity factor (k′) and the solute concentration in the mobile phase (Cm). Provided that k′Cm≤10−2 M, linear chromatographic behaviour was observed for both sorbents, the maximum capacities of which were found greater than 1mmolg−1.
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    Estimation of the band broadening contribution of HPLC equipment to column elution profiles (1987)
    Springer
    Chromatographia 23 (1987), S. 189-194 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Instrument bandbroadening by extrapolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Methods to determine the contribution of the chromatographic equipment to the total band broadening which involve replacing the column by a union or a capillary tube are not suitable as they involve a fundamental change in the chromatographic system. The linear extrapolation method, based on the estimation of the relative influence of the instrument variance on solutes with different capacity factors, is a more attractive alternative method since the column remains in the chromatographic system. This method is only valid when a number of conditions are satisfied. By meeting these conditions the error in the instrument variance by using the linear extrapolation method was determined. At the same time, ways to minimise these errors were studied. Use of the linear extrapolation method in combination with conventional columns of 4.6 mm i.d. appears to yield inaccurate results. In combination with microbore columns the method can be used, provided the columns have a maximum length of 5cm and contain a packing material with a particle size of 2 or 3μm. The error in the determined instrument variance is then of the order of 2μl2.
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    Non-aqueous reverse-phase HPLC analysis of triglycerides (1987)
    Springer
    Chromatographia 23 (1987), S. 209-214 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Review of triglyceride analysis ; Column temperature gradients ; Combined LC and other techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The present review cites 54 papers dealing with reversephase HPLC analysis of triglycerides. The objective of the review was not merely to list the main contributions made in recent years but also to present a discussion of those papers representing qualitative advances and improvements helping to obviate the difficulties associated with this type of analysis. The use of mobile phase polarity and column temperature gradients and the combination of HPLC with other analytical methods such as mass spectrometry or GLC analysis of fatty acids are examples of such contributions.
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    Chromatographic packings made by solide phase synthesis (1987)
    Springer
    Chromatographia 23 (1987), S. 254-256 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Synthesis of stationary phases ; Influence of surface pH ; Influence of temperature, concentration and reaction ; time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new way to produce liquid chromatographic stationary phases is suggested. The method is based upon a solide-phase reaction between the silica surface and the adsorbed silane molecules. The role of surface pH is demonstrated. The influence of other reaction conditions (concentration of the silane solution, effect of temperature and reaction time) is discussed.
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    Preparation of chiral stationary phase via activated carbamate intermediate for liquid chromatographic optical resolution (1987)
    Springer
    Chromatographia 23 (1987), S. 727-730 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Succinimido carbamate intermediates ; Amino acid enantiomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chiral stationary phases (CSPs) for liquid chromatography were prepared by the way of an activated carbamate intermediate. The amino group of aminopropylsilyl silica gel was first activated by carbamylation with disuccinimido carbonate (DSC). The obtained activated carbamate silica gel (ACsil) proved useful as an intermediate for the preparation of urea-type CSPs. The reaction of ACsil with (S)- of (R)-1-(α-naphthyl)-ethylamine gave naphthylethylurea type CSPs. These CSPs were also obtained directly from aminopropylsilyl silica gel by its reaction with optically active (S)- or (R)-succinimido 1-(α-naphthyl)ethyl carbamate (SINEC). Several phenylthiohydantoin amino acid enantiomers and p-bromophenylcarbamyl amino acid enantiomers were resolved on the CSPs by elution with aqueous mobile phase.
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    Determination of the concentration of silanol groups by a chemical reaction with methyllithium and GC measurements of evolved methane (1987)
    Springer
    Chromatographia 23 (1987), S. 767-769 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Bonded silica ; Residual silanol groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Silanol groups of chromatographic material surfaces were determined by chemical reaction with methyl-lithium. Evolved methane was measured by a gas chromatographic method using a column packed with molecular sieves. This chromatographic technique leads to very reproducible results, particularly for the control of the hydroxylation of a silica gel and for the analysis of residual groups at the surface of bonded silica.
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    URL: http://dx.doi.org/10.1007/BF02312671
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    Determination of low boiling aldehydes in air and exhaust gases by using annular denuders combined with HPLC techniques (1987)
    Springer
    Chromatographia 23 (1987), S. 829-834 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aldehydes ; Annular denuder ; Environmental analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An improved procedure for the HPLC determination of C1−C3 aldehydes in environmental samples is described. These air pollutants are quantitatively collected on annular denuders coated with 2,4-Dinitrophenylhydrazine and analyzed as hydrazone derivatives by HPLC with UV absorbance and voltammetric detection. Collection efficiencies of aldehydes are reported and compared with other available methods. Practical examples of the application of the method are given.
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    URL: http://dx.doi.org/10.1007/BF02311408
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    Assay for urinary estriol during the menstrual cycle based on extraction by a graphitized carbon black cartridge followed by high-performance liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 835-838 
    Details
    ISSN: 1612-1112
    Keywords: Estriol ; Urine ; Menstrual Cycle ; Column liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatography (HPLC) assay for estriol in nonpregnancy urine is described. After Enzymic hydrolysis, the estriol is extracted from urine by the sorbent trap technique utilizing graphitized carbon black (Carbopack B). After some washing steps, estriol is desorbed by a suitable solvent system. After solvent removal, the sample is injected into an HPLC column for estriol quantification. Analytical recovery of estriol was 96.1%. The precision of the method was 2.6 and 4.9% respectively at 145 and 10.6ng/ml of urine. The limit of sensitivity was set at 0.8 ng/ml of urine. The mean contents of estriol in the follicular and luteal phases were respectively 11.3 and 38.8 ng/ml of urine.
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    URL: http://dx.doi.org/10.1007/BF02311409
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    Influence of column temperature, water content, polarity, and acidity of isohydric solvents on the separation of butyrophenones on silica gel (1987)
    Springer
    Chromatographia 23 (1987), S. 893-898 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Isohydric solvents ; Butyrophenones ; Direct-silica gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The behaviour of butyrophenones in high performance liquid chromatography on silica gel using isohydric solvent systems has been studied. The influence of column temperature, water content, acidity and polarity of isohydric solvents on the retention, column efficiency and resolution of a series of butyrophenones have been investigated. Through the results obtained more insight has been gained into the theoretical aspects of the adsorption process on silica gel with isohydric solvent systems.
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    URL: http://dx.doi.org/10.1007/BF02261467
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    Large scale purification of synthesized oligodeoxyribonucleotides by reversed-phase chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 909-914 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase separation ; Oligodeoxyribonucleotides ; Isolation of pure material
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase chromatographic column suitable for the purification of chemically synthesized large oligodeoxyribonucleotides (oligo-DNA) was prepared. The specifications of this column are; the selected silica (Toyo Soda silica) with large pore size (at least 150 Å) and small particle diameter (5 μm desired) should be grafted only with monochloro alkylating reagent of long alkyl chain (sufficiently C18) so that the carbon content of the resultant packing material is 15–16%. Using this column, we could isolate the targeted large oligo-DNA (up to 50mer) in a large scale (75 μg per one cycle) from the impurities in the reaction mixture formed during the automated synthesis by the phosphite method.
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    URL: http://dx.doi.org/10.1007/BF02261470
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    A critical review of some liquid chromatography systems for the separation of sugars (1987)
    Springer
    Chromatographia 23 (1987), S. 292-300 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Separation of sugars ; Review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This contribution to the problems of carbohydrate (sugar) column liquid chromatography, evaluates several currently used systems (reversed phase octadecylated silica gel, amino modified silica gel, cation exchangers on polystyrene and on silica gel basis, polyol derivatised silica gel and anion exchange systems). The elution pattern, analysis time, column efficiency and column life time expectancy are considered to be the important points for this comparison. The application of silica gel-based cation exchanger and of polyol derivatised silica gel is new to this field. The comparison and/or evaluation tries to be critical and to come to a conclusion for the choice of a recommended system.
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    URL: http://dx.doi.org/10.1007/BF02311783
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    Liquid chromatographic determination of dimethadione and trimethadione in human serum on octadecyl treated microporous glass columns (1987)
    Springer
    Chromatographia 23 (1987), S. 325-327 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Packings of octadecylated microporous glass ; Dimethadione and trimethadione in serum ; Pancreatic stones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The liquid chromatographic determination of trimethadione (TMO) and its methabolite, dimethadione (DMO) were studied by high-performance liquid chromatography (HPLC) on octadecyl-modified microporous glasses, prepared with toluene solution containing octadecyl-dimethylchlorosilane, using two types of microporous glass with various mean pore diameters and/or specific surface areas. Using acetonitrile-water mixtures as eluents, TMO and DMO in human serum were separated on the glasses studied, but with different degrees of resolution. In this present study, we report the development of a rapid and selective HPLC method for the simultaneous analysis of TMO and DMO in human serum.
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    URL: http://dx.doi.org/10.1007/BF02316176
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    Characterization of some commercial poly (styrene-divinylbenzene) copolymers for reversed-phase HPLC1 (1987)
    Springer
    Chromatographia 23 (1987), S. 341-349 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cross-linked polystyrene ; Characterization of surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The properties of the poly(styrene-divinylbenzene) copolymers PRP-1 and PLRP-S have been studied by infrared spectroscopy and chromatographic techniques. The following results were obtained: PRP-1 and PLRP-S are spectroscopically very similar. Their surfaces are chemically neither homogeneous nor stable during use. Retained nonpolar solutes should be eluted with a mobile phase containing tetrahydrofuran. Uncharged acids and anions can be chromatographed without difficulty. Cations of amines should be chromatographed only with a mobile phase of low pH. Uncharged amino-alcohols cannot be chromatographed without the addition of a competitor.
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    URL: http://dx.doi.org/10.1007/BF02316180
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    Preparation of silanized silica with high ligand density. The effect of silane structure (1987)
    Springer
    Chromatographia 23 (1987), S. 442-446 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phases ; Kinetics of silanization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A wide-pore silica for HPLC with a particle size of 7.5 μm, specific surface area of 360m2/g, pore diameter of 20 nm and pore volume of 2.1 cm3/g was silanized with n-octadecyldimethyl-chlorosilane (ODMCS), n-octadecyldimethylmetoxysilane (ODMMS) and n-octadecyldimethyl-dimethylaminosilane (ODMAS), in sealed glass ampoules. The ligand density obtained with an excess of ODMCS and ODMMS was found to be limited by reaction equilibrium; at low (〈50%) conversion of the surface silanols, the reaction displays pseudo-first-order kinetics. Silanization with ODMAS, which seems to be sterically controlled at higher conversions, yields a relatively high concentration of bonded octadecyl ligands (4.24μmol/m2).
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    URL: http://dx.doi.org/10.1007/BF02311822
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    HPLC on pentalfuoroanilinopropyl silica gel (1987)
    Springer
    Chromatographia 23 (1987), S. 684-685 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pentafluoroanilinopropyl silica gel ; Donor-acceptor complexes ; Aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of a new pentafluoroanilino-phase for HPLC is described. The retention times (tr) of about twenty aromatic hydrocarbons have been determinated. It has been shown that the aromatics were eluted according to the number of rings. The influence of water content in the mobile phase is commented.
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    URL: http://dx.doi.org/10.1007/BF02311500
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    HPLC determination of thiol drugs in pharmaceutical formulations using ethacrynic acid as a precolumn ultraviolet derivatization reagent (1987)
    Springer
    Chromatographia 23 (1987), S. 680-683 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiol drug analysis ; Derivatization by ethacrynic acid ; Pharmaceutical formulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high performance liquid chromatographic method has been developed for the determination of aliphatic thiol drugs, such as N-acetyl-L-cysteine, captopril and mercaptopropionylglycine in pharmaceutical formulations. The procedure involves a precolumn derivatization of the thiol drug with ethacrynic acid followed by reversedphase HPLC separation and UV detection. The conditions for a rapid and selective reaction of the thiols with ethacrynic acid have been investigated. The method proved to be suitable for a reliable and selective quality control of commercial dosage forms of the examined thiol drugs.
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    URL: http://dx.doi.org/10.1007/BF02311499
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    Trace analysis of sugars by HPLC and post-column derivatization (1987)
    Springer
    Chromatographia 23 (1987), S. 657-662 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Post-column derivatization ; Sugar analysis ; Wine characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A HPLC system with post-column derivatization for the quantitative analysis of sugars in complex matrices is described. As reagent a 0.2% solution of thymol in concentrated sulfuric acid has been used. The reaction is sensitive with reducing as well as non reducing sugars whereas sugar alcohols are discriminated. With this reagent and separation of sugars at high pH values with an anion exchange column it is possible to detect sugars in the ng range. Hence, it is possible to characterize wines not only by their fructose and glucose content but also by differences in the distribution of the other not fermentable sugars like trehalose, arabinose, galacturonic and glucuronic acid.
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    URL: http://dx.doi.org/10.1007/BF02311495
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    On-column catalysis of hydratization equilibria during liquid chromatographic analysis of acetaldehyde and formaldehyde (1987)
    Springer
    Chromatographia 23 (1987), S. 709-712 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polymer-based support ; Aldehydes ; Fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The aldehydes were separated by reversed phase chromatography on a polymer-based support. Acid catalysis on the column was needed to obtain sufficiently fast equilibrium between acetaldehyde and its hydrate. Deuterium labeled acetaldehyde (D3) yielded complete separation from the nonlabeled compound, probably due to a difference in hydratization. Fluorescent products were obtained by reaction between the aldehydes and a mixture of ammonia and dimedone (5.5-dimethyl-1.3-cyclohexanedione). The fluorescence was detected at 460 nm after excitation at 390 nm. A reaction time of 42 seconds at 90°C in a knitted teflon capillary produced detection limits of 0.5 and 1 ng for acetaldehyde and formeldehyde, respectively. A method for preparation of a stable reagent with low background fluorescence is described.
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    URL: http://dx.doi.org/10.1007/BF02312660
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    Effects of reducing agents on the determination of thiolic compounds in the presence of their disulfides using bimane pre-column derivatization (1987)
    Springer
    Chromatographia 23 (1987), S. 717-721 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiols and disulfides ; Fluorescence derivatization ; Monobromobimane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The influence of reducing agents (sodium borohydride, tributylphosphine, dithioerythritol and dithiothreitol) on the conversion of disulfides into their parent thiols, with specific application to cysteine was investigated. Dithioerythritol and dithiothreitol were found to be most suitable for this reaction. A contact time of one hour at room temperature provided quantitative reduction as tested using cystine as a pure disulfide standard. A modified fluorescence labelling procedure with monobromobimane followed by reversed-phase HPLC allows quantitation of the parent thiol and the disulfide content when completing the labelling reaction with and without preliminary treatment with reducing agent. The effects of various bimane reducing agent ratios on the yield of the reaction are discussed. Precautions should be taken when dealing with complex matrices with respect to reagent concentrations and ratios.
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    Activated carbamate reagent as chiral derivatizing agent for liquid chromatographic optical resolution of enantiomeric amino compounds (1987)
    Springer
    Chromatographia 23 (1987), S. 899-902 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chrial separations ; Succinimido carbamate derivatives ; Propranolol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A chiral derivatization reagent having activated succinimido carbamate moieties were developed for the optical resolution of enantiomeric amines by high-performance liquid chromatography. Succinimido R-(+)- or S-(−)-1-phenylethyl and R-(+)- or S-(−)-1-(α-naphthyl)-ethyl carbamates were synthesized by the reaction of optically active phenylethyl and naphthylethyl amines with discuccinimido carbonate (DSC). These reagents reacted with both primary and secondary amine enantiomers such as amino acids and β-amino alcohols to give the corresponding diastereomeric urea derivatives. These diastereomers were efficiently separated by reversed-phase liquid chromatography and detected by their absorption or the fluorescence of the chromophores. The chiral derivatization procedure was applied to the separation and determination of enantiomeric propranolol in serum.
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    URL: http://dx.doi.org/10.1007/BF02261468
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    Optimization of the separation of polymethoxylated flavones in reversed phase liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 15-20 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase operation ; Calculation of optimum solvent composition ; Polymethoxylated flavones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An optimization procedure for the chromatographic separation of polymethoxylated flavones is described. A polyhedron working volume is drawn from a truncated tetrahedron constructed from the four solvents selected. The response function is an n'th degree polynomial the coefficients of which are calculated through the least squares method by means of B=(X′X)−1X′Y in which X′X is the information matrix (X′X)−1 the variance covariance matrix. X is the matrix of the model (polynomial built from the selected experiments) and X′ the transposed matrix. Y is the quality of the chromatogram defined by the resolution of each pair of solutes. An exchange algorithm matrix yields the minimum number of runs necessary to obtain a correct B. Isoresponses curves are drawn by intersection of a cubic volume which includes the polyhedron to give a better insight. An optimal zone is then determined and provides the solvent composition. An optimized chromatogram of 8 methoxylated flavones demonstrates the application of the method.
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    URL: http://dx.doi.org/10.1007/BF02310411
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    Chromatographic determination of lactulose (1987)
    Springer
    Chromatographia 23 (1987), S. 132-136 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Thin-layer chromatography ; Analysis of lactulose in carbohydrate mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Lactulose is a disaccharide with important implications in medicine, nutrition and dairy technology. It has to be determined usually as a minor component in complex matrices containing many other sugars. This paper describes the different chromatographic techniques (planar, liquid and gas chromatography) which have been proposed for the separation and quantification of lactulose in mixtures with other carbohydrates; the advantages of each technique are compared and some features where more research is necessary are outlined.
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    URL: http://dx.doi.org/10.1007/BF02312889
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    A study of the liquid chromatography of some fungicidally active arylsulphonohydrazides (1987)
    Springer
    Chromatographia 23 (1987), S. 328-330 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Arylsulphonohydrazides ; On-column hydrolysis ; Fungicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A number of fungicidally active arylsulphonohydrazides are examined by normal- and reversed-phase liquid chromatography. Although good separations are achieved by reversed-phase LC, difficulties are encountered due to analyte hydrolysis. On the other hand, satisfactory analyses are possible by normal-phase LC particularly on modified silicas.
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    URL: http://dx.doi.org/10.1007/BF02316177
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    Rapid extraction of codeine and morphine in whole blood for HPLC analysis (1987)
    Springer
    Chromatographia 23 (1987), S. 377-378 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Codeine and morphine in blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and efficient procedure is described for the extraction and analysis of codeine and morphine in whole blood. Red blood cells were fragmented by sonication and the blood sample extracted by passing through a bonded silica column (Bond Elute®). The adsorbed drugs were washed and eluted followed by analysis by HPLC. Recoveries were between 95–100% at 5 ng/ml concentrations.
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    URL: http://dx.doi.org/10.1007/BF02316187
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    Liquid chromatographic analysis with electrochemical detection for metoclopramide in human plasma (1987)
    Springer
    Chromatographia 23 (1987), S. 651-652 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Metoclopramide ; Electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, reproducible liquid-chromatographic method for determination of metoclopramide anti-emetic and anti-spasmodic agent is described. Metoclopramide is extracted from alkalinized plasma into diethylether, then separated with a sperisorb CN column and measured through amperometric detection at +1,4 volt vs Ag/ AgCl. The average extraction recovery was 92%. Standard curves were linear and reproducible from 0.05 to 1.5 mg/ L. Within-day CV was better than 6%.
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    URL: http://dx.doi.org/10.1007/BF02311493
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    A solvent-free sampling method for airborne toluene diisocyanate (1987)
    Springer
    Chromatographia 23 (1987), S. 507-511 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Toluene Diisocyanate in air ; Collector for air sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A useful method of sampling and measurement of toluene diisocyanate concentration in atmosphere is described. The sampler consists of glass-fibre filters impregnated with the reagent 1-(2-methoxyphenyl)piperazine1 so that the 2,4 and 2,6 isomers of TDI react to form urea derivatives which are analysed by high performance liquid chromatography in isocratic mode on cyan-amino and C18 bonded phases. A dynamic system was used to generate standard atmospheres of TDI and to validate the sampling method within the humidity range of 0% to 75%. A coated filter, a bubbling solution and an impregnated silica gel were compared as samplers requiring the piperazine reagent in performance experiments.
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    URL: http://dx.doi.org/10.1007/BF02309420
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