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  • Column liquid chromatography  (349)
  • ddc:330
  • Seismology
  • Industrial Chemistry
  • Inorganic Chemistry
  • Springer  (353)
  • 1985-1989  (351)
  • 1950-1954  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Chromatographic analysis of penstemide and serrulatoloside by high-performance liquid chromatography and gradient thin-layer chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 24-26 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Penstemide and serrulatoloside
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Penstemide and serrulatoloside, two iridoids of similar molecular structure, were separated by stepwise gradient TLC in a straight-phase systems (silica-ethyl acetate+isopropanol) and by HPLC in a reversed-phase system (ODS-silica — water+methanol).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290399
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  • 2
    Electronic Resource
    Electronic Resource
    RPLC retention of 1,ω-di(alkoxy)-polysulphides (1989)
    Springer
    Chromatographia 27 (1989), S. 27-30 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; 1,ω-Di(alkoxy)-polysulphides ; Retention contributions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reaction of S2Cl2 with alcohols yields products, the reversed-phase liquid chromatograms of which are similar to those of dialkyl-polysulphides RSnR, i.e., they represent homologous series. Four of the products were identified via GC-MS as 1,ω-di(alkoxy)-polysulphides having the general structure ROSnOR. Retention contributions of alkyl groups R and sulphur atoms in the −Sn — chain are not much different from values observed with polysulphides. The effect of oxygen, however, is only about −100 index units per O atom, while in dialkyl ethers values of −500 units have been reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290400
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  • 3
    Electronic Resource
    Electronic Resource
    The effect of alcoholic mobile phase modifiers on retention and stereoselectivity on a commercially available cellulose-based HPLC chiral stationary phase: An unexpected reversal in enantiometric elution order (1989)
    Springer
    Chromatographia 27 (1989), S. 15-18 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral recognition process ; Enantiomeric elution order ; Mobile phase modifiers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three enantiomeric solutes, a sulphoxide, a piperidine derivative and a methyl ester have been chromatographed on an HPLC chiral stationary phase (CSP) based upon cellulose-tribenzoate (Chiralcel OB-CSP). The mobile phases used in the study were composed of hexane modified with homologous series of primary, secondary and cyclic alcohols. Interesting reversals in enantiomeric elution order have been observed for 2-phenoxypropanoic acid methyl ester associated with changes in chain length or ring size of the alcohol mobile phase modifier. The results of the study suggest that at least two chiral recognition mechanisms operate on the OB-CSP and point out the importance of acquiring elution order data in all studies involving chiral stationary phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290397
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  • 4
    Electronic Resource
    Electronic Resource
    Separation of bromo- and iodosubstituted thyronines by high-performance liquid chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 101-104 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bromo/iodosubstituted thyronines ; Mobile phase optimization ; Radioimmunoassay detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase high performance liquid chromatographic method on C-18 bonded silica is described for the separation of trisubstituted iodo/bromothyronines, which exert thyroid hormone activity. The composition of the mobile phase has been systematically optimized resulting in a ternary mixture of methanol/acetonitrile/water acidified with trifluoroacetic acid. The applicability of ultraviolet absorption detection, amperometric detection and off-line radioimmunoassay was investigated. The latter method allows detection of the different iodo/bromothyronines down to 40–120 ng/l mobile phase; this sensitivity is high enough for application to thyroid hydrolysates in order to clarify the question as to whether bromine can substitute iodine in the biosynthesis of thyroid hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265858
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  • 5
    Electronic Resource
    Electronic Resource
    Retention of 1,ω-bis-(dialkylamino)-polysulphides and related compounds in reversed-phase HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 113-117 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention contribution of nitrogen ; Effect on methylene and sulphur chains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reaction of secondary amines R2NH with disulfur dichloride S2Cl2 in dichloro methane yields mixtures of bis-dialkylamino polysulphides R2N−Sn−NR2 with sulphur chain lengths varying from ns=2 to 14. The S chains are believed to be non-branched. The compounds form homologous series in each of which sulphur atoms give a constant contribution to retention. The sulphur retention index depends slightly on the carbon number in the terminal alkyl groups R. The presence of nitrogen lowers retention. The index increment of N is ca. −160 units, which is distinctly less negative than values found in alkylamines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265861
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  • 6
    Electronic Resource
    Electronic Resource
    LC-MS of enzymatic peptic haemoglobin hydrolysate produced at the pilot-plant level (1989)
    Springer
    Chromatographia 27 (1989), S. 128-134 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion chromatography ; Fast atom bombardment-MS ; Peptic haemoglobin hydrolysate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the ready identification of any peptide isolated from a complex peptic haemoglobin hydrolysate produced on the pilot-plant scale. A combination of size exclusion and reversed-phase, high-performance liquid chromatography have proved to be a useful strategy for fractionation of such a mixture. This technique enabled pure peptides from the total hydrolysate to be obtained. Amino acid analysis and fast atom bombardment mass spectrometry provided the accurate composition and molecular weight of any isolated peptide. Molecular weights are compared with those deduced from size-exclusion chromatography (SEC) and the usefulness of SEC is discussed. The procedure described in this study will be useful for acquiring a better knowledge of such an hydrolysate and could be extended to other crude protein digests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265864
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  • 7
    Electronic Resource
    Electronic Resource
    Chromatographic and potentiometric determination of dissociation constants of weakly basic Aroma compounds (1989)
    Springer
    Chromatographia 27 (1989), S. 194-200 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dissociation constants ; Potentiometric titration ; 2,4-Dimethylthiazole ; Trimethylpyrazine ; Methyl anthranilate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase liquid chromatography on two stationary phases—octadecylbonded silica Partisil ODS-3 and polystyrene-divinylbenzene resin PRP-1—and potentiometric titration in the water/methanol mobile phase were investigated in order to determine the dissociation constants of three weakly basic aroma compounds, namely trimethyl pyrazine, 2,4-dimethyl thiazole and methyl anthranilate. The data obtained from both methods are quite consistent and compare favourably to values found in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260445
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  • 8
    Electronic Resource
    Electronic Resource
    Rapid reversed-phase chromatographic separation and determination of selenum and tellurium (1989)
    Springer
    Chromatographia 27 (1989), S. 292-296 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Selenium(IV)-tellurium(IV) separation ; Flow-through coulometric detector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of selenium and tellurium has been investigated with two different reversed-phase chromatographic methods, using P-350 (methyl-bi-isooctyl phosphate) and TBP (tributyl phosphate) as the stationary phases. HCl, HBr, NaCl and NaBr were employed as mobile phase components in both methods. The results suggested that the separation mechanism corresponds to the formation of TeCl (or TeBr) and P-350H (or TBPH) ion associate. A coulometric flow-through detector was applied to determine Se(IV) and Te(IV). Complete separation and quantitative determination of Se and Te could be achieved in 10 minutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02321271
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  • 9
    Electronic Resource
    Electronic Resource
    Selectivity of alkyl-bonded phases in reversed-phase liquid chromatography of hydrophobic compounds (1989)
    Springer
    Chromatographia 27 (1989), S. 371-377 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alkyl-bonded silica gel ; Enthalpy ; Van der Waals volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Starting from silica gel with a purity of 99.999%, octadecyl-(ODS), octyl-(C8) and propyl-(C3) bonded silica gels were synthesized, and end-capped by trimethyl groups. The pore size was 150 Å and the specific surface area was 320 m2/g. The ODS and C8 silica gels were stable in both acidic and basic solutions. The selectivity of these bonded-silica gels was examined from the difference of the retention behavior of alkanes (Al−Al), alkylbenzenes (Ph−Al), alkylalcohols (Al−OH) and polyaromatic hydrocarbons (PAH) in aqueous acetonitrile. On these packings the log k′ values decreased in the order Al−Al〉Ph−Al〉PAH〉Al−OH. Furthermore, the chromatographic behavior of these compounds was measured on polymer-coated octadecyl-bonded silica gel (CAP) and octadecyl-bonded vinyl alcohol copolymer gel (ODP). The selectivity was verified from the value of R* of these compounds: $$R = R_v + R^* $$ where R is the retention time, and Rv is the retention time of an alkane having the same Van der Waals volume as the analyte. The R* values indicated that this ODS had more selectivity than C8 and C3, however R* on C8 showed a very good correlation with R* on C3. Their retention behavior on CAP was similar to that of ODS, however, their capacity ratios measured on CAP were smaller than those on ODS. The ODP has selectivity for the retention of aromatic compounds, because PAHs were retained strongly on this column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02321286
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  • 10
    Electronic Resource
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    Determination ofAlternaria mycotoxins in foodstuffs by gradient elution liquid chromatography with electrochemical detection (1989)
    Springer
    Chromatographia 27 (1989), S. 425-430 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alternaria mycotoxins ; Food analysis ; Electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The electroactivity of majorAlternaria mycotoxins has been explored in order to devise a liquid chromatographic-electrochemical detection (LC-EC) method for the determination of these toxic metabolites in fungal cultures and in naturally contaminated foodstuffs. Alternariol, alternariol methyl ether, altertoxin-I and altertoxin-II have been found to be electroactive and could be detected at sub-nanogram levels. Advantages and limitations of dual electrode (screen mode) coulometric detection and single electrode amperometric detection are presented and discussed. The feasibility of electrochemical detection in gradient elution liquid chromatography as well as its applicability to the analysis of contaminated foodstuffs is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319558
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  • 11
    Electronic Resource
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    Automatic measurement of some common herbicides by LC using simultaneous UV detection and electrochemical detection in series (1989)
    Springer
    Chromatographia 27 (1989), S. 431-435 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; UV diode array detection ; Electro chemical detection ; Herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An automated procedure is described for simultaneous UV detection at three different wavelengths and electro chemical detection in series of some residual herbicides. UV spectra of nine compounds of different compound groups are presented. Liquid-liquid extraction with dichloromethane and an enrichment of about one thousandfold has been used. Recovery rates after enrichment and detection limits of four s-triazine, three phenyl urea herbicides, metazachlore and metamitrone in river and drinking water are shown. It is concluded that the herbicides examined can be detected at levels between 10ng l−1 and 50ngl−1, without the necessity of derivatisation or clean-up processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319559
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  • 12
    Electronic Resource
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    Separation and purification of porcine pancreatic enzymes by serial operation of ion-exchange and affinity columns (1989)
    Springer
    Chromatographia 27 (1989), S. 449-454 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion exchange and affinity columns in series ; Porcine pancreatic enzymes ; Trypsin and elastase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to separate and purify some of the enzymes contained in porcine pancreas, operation of an ion-exchange column in series with an affinity column has been used. The enzymes dealt with possess very similar molecular weights, isoelectric points and active sites. Hence they are difficult to separate and purify by traditional separation and/or purification methods. CM-Sepharose anion-exchange resin adsorbs elastase and trypsin at low pH (4.5) and desorbs them at high pH (9.0) and high ionic strength. Chitin-CHOM affinity adsorbent adsorbs trypsin at high pH (8.0) and desorbs it at low pH (2.5). By virtue of this complementary relationship two chromatographic columns were connected in series for facilitating the separation and purification of elastase and trypsin from porcine pancreas. The result showed that the specific activities of elastase and trypsin had been increased 16 and 22 fold respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319562
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  • 13
    Electronic Resource
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    Determination of atmospheric ammonia as m-toluamide by denuder sampling and HPLC-UV detection (1989)
    Springer
    Chromatographia 28 (1989), S. 27-30 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Atmospheric ammonia ; m-Toluamide derivative ; Annular denuder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and reliable method for routine measurement of ammonia in ambient air is described. It is based on the collection of ammonia on H3PO3-coated annular denuders and its subsequent derivatization withm-toluoyl chloride (MTC) in alkaline acetonitrile. The resultingm-toluamide is determined by reversed phase HPLC with UV detection at 230 nm. The limit of dotection is about 0.3μg m−3 for NH3 in air samples collected at 151 min−1 for one hour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290378
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  • 14
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    High-performance-liquid chromatography ofThermus aquaticus 50S and 30S ribosomal proteins (1989)
    Springer
    Chromatographia 28 (1989), S. 39-44 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thermus aquaticus ; Ribosome ; 50S and 30S subunit proteins ; Gel electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The ribosomal 50S and 30S subunit proteins (r-proteins) ofThermus aquaticus have, for the first time, been characterized by size exclusion chromatography (SEC) and by reversed phase high performance liquid chromatography (RPC). To ensure that the best resolution in the RPC was obtained. the elution conditions, such as gradient time, flow rate, temperature, ionic strength of the eluent and the type of stationary phase were optimized. Correlation between experimentally found retention times and those predicted by DryLab G was better than 0.7% over 30 peaks. Protein fractions from RPC runs were desalted and processed by gel electrophoresis so that the ribosomal proteins could be identified by their position on SDS-polyacrylamide gels. The enhanced speed and quality of separation which has been achieved in this study is expected to bring advantaces in experimental work with ribosomal proteins as well as with other biopolymers. In our case the high resolution technique provides a basis for the preparation of a collection of individual ribosomal protein components for future rRNA-protein interaction studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290381
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  • 15
    Electronic Resource
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    Polymer coated stationary phases for liquid chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 19-23 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparation of stationary phases ; Polymer coated stationary phases ; Polymer-octyl bonded phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polymethyloctylsiloxane-coated stationary phases have been prepared for liquid chromatography, by thermal reaction. The influence of the reaction conditions on retention and efficiency of test substances with different structures has been discussed. The materials have good stability in both acidic and basic eluents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290376
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  • 16
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    HPLC and electrophoresis — Competitors or partners (1989)
    Springer
    Chromatographia 28 (1989), S. 89-91 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrophoresis ; Comparison of HPLC and electrophoresis ; Proteins, peptides and amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Protein structure analysis is an indispensible tool in modern biological research. However, the isolation of a protein or the separation of peptides in a form suitable for sequence analysis is a considerable technical challenge. The two predominant separation methods in protein biochemistry are chromatography and electrophoresis. In this paper the position, advantaged and disadvantages of both HPLC and electrophoresis for the separation of amino acids, peptides and proteins in protein structure analysis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290389
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  • 17
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    Simultaneous determination of pseudouridine and creatinine in urine by HPLC with polarographic detection (1989)
    Springer
    Chromatographia 28 (1989), S. 605-609 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detection ; Pseudouridine ; Creatinine ; Urine analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The anodic behaviour of pseudouridine a modified nucleoside proposed as tumoral marker, has been studied at a mercury electrode. A method for its determination in urine samples by liquid chromatography with indirect anodic polarographic detection has been developed. The method is simple, highly selective and permits the direct injection of urine after dilution (1∶20) with mobile phase. Creatinine, which also gave an anodic response on mercury, could be simultaneously determined and used as an “internal standard” for Psi. This allowed the pseudouridine/creatinine ratio determination in a single run on the same specimen and the use of urine samples collected randomly instead of the 24h collection. The within-day RSD% for pseudouridine/ creatinine peak areas ratio was 3.4%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260686
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  • 18
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    Evaluation of synthetic procedures for the chemical modification of alumina for HPLC (1989)
    Springer
    Chromatographia 28 (1989), S. 565-568 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; New bonded phases ; Alumina ; Protein separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several reactions are tested for the chemical modification of alumina. These include the following: chlorination of the surface hydroxyls followed by reaction with an organolithium compound; chlorination of the surface hydroxyls followed by reaction with a Grignard reagent; chlorination of the surface hydroxyls followed by reaction with an amine; chlorination of the surface hydroxyls followed by reaction with an alcohol; direct reaction of the alumina with an organochloroalane and direct reaction of the alumina with an alcohol. Only the first reaction gave a product which contained enough bonded organic material to be easily detected by FTIR. Preliminary stability tests show that the product of the first reaction retains the bonded organic material when exposed to nonpolar and polar organic solvents as well as aqueous solutions of pH 1.0, 7.0 and 12.0. Chromatographic testing establishes reversed-phase behavior for alkylarylketones as solutes and the bonded phase displays good biocompatibility for a series of protein standards.
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    URL: http://dx.doi.org/10.1007/BF02260678
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  • 19
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    Separation of adenosine triphosphate and its degradation products in innervated muscle of the frog by reverse phase high-performance liquid chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 610-612 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Adenosine phosphates ; Adenosine phosphate degradation products ; Innervated frog muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Adenosine mono-, di- and triphosphates, inosine monophosphates, adenosine, inosine and hypoxanthine were separated in a single run by high-performance liquid chromatography with UV detection. AC-18 reversephase column was used. An isocratic elution with 100mM phosphate buffer (KH2PO4) pH6.5 and 1.2% methanol, followed by a 5 minute linear gradient up to 15% methanol after the 10th minute was performed during each run with a flow rate of 1.25ml/min. The time required for each analysis was 25 minutes. The detection limit for each substance ranged from 3 to 5 pmol. All the substances under study were detected in the incubation medium when adenosine triphosphate was exogenously applied to the innervated frog sartorius muscle.
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    URL: http://dx.doi.org/10.1007/BF02260687
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  • 20
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    Analysis of preservatives in cosmetics—Methylisothiazolones (1989)
    Springer
    Chromatographia 28 (1989), S. 34-38 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Methylisothiazolones ; Preservatives ; Analysis of cosmetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Antimicrobially active formulations based on 2-methyl-3(2H)-isothiazolone and 5-chloro-2-methyl-3(2H)-isothiazolone (Kathon CG, Euxyl K 100) are incorporated into manufactured cosmetics as preservatives. In this paper we report on the analysis of these active components by means of liquid chromatography. It is conventional for the original methylisothiazolone components in cosmetics to be analyzed by reversed phase high-performance liquid chromatography after column chromatographic separation and flash chromatographic purification. In our new analytical method the methylisothiazolones are converted into the respective β-thiosubstituted acrylamide derivatives, which are ionic substances, with the help of the nucleophilic reagent hydrogensulfite. An ion pair high-performance liquid chromatographic method has been developed for the separation and quantification of these derivatives.
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    URL: http://dx.doi.org/10.1007/BF02290380
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  • 21
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    Molecular interactions in liquid adsorption chromatography with mixed mobile phase. Solvation of the chromatographed substance in a ternary mobile phase (1989)
    Springer
    Chromatographia 28 (1989), S. 151-156 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Molecular interactions ; Association effects ; Analyte solvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The linear Jaroniec equation has been utilized for the description of chromatographic systems in which the test substance molecule is solvated by the solvent molecules. A possibility of the formation of multimolecular solvates in the bulk phase has been confirmed. The measurements were made using liquid adsorption chromatography with ternary mobile phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319638
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  • 22
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    HPLC Analysis of complex mixtures of triglycerides using gradient elutions and an ultraviolet detector (1989)
    Springer
    Chromatographia 28 (1989), S. 183-188 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Triglycerides ; Gradient elution ; UV detector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method of reserved-phase HPLC analysis for mixtures of triglycerides (TG's) that provides good resolution at acceptable analysis times for high-ECN TG's has been developed. An elution gradient of methyltert-butyl-ether (MTBE) in acetonitrile (ACN) was used with an ultraviolet detector operated at 215nm. The effect of the proportion of MTBE in the mobile phase, gradient time, temperature and sample solvent on TG retention and resolution was studied. Linear relationships were derived between the logarithm of the capacity factor (log k'), and the logarithm of selectivity (log α) and the above-mentioned chromatographic factors. The conditions selected were: an elution gradient of from 23 to 30% MTBE, an elution gradient time of 25 minutes, and a temperature of 30°C, which provided good resolution of soybean oil TG's in less than 30 minutes.
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    URL: http://dx.doi.org/10.1007/BF02319644
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  • 23
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    Determination of potential degradation products of piroxicam by HPTLC densiometry and HPLC (1989)
    Springer
    Chromatographia 28 (1989), S. 197-202 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin layer chromatography ; Piroxicam ; Piroxicam degradation products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPTLC densitometry and HPLC are considered for the simultaneous determination of the degradation products of piroxicam (2-aminopyridine, DP-I and DP-II). The substances were separated on silica gel with fluorescence indicator in ethylacetate — toluene — diethylamine (10∶10∶5) and toluene — absolute ethanol — glacial acetic acid (8∶1.2∶0.5) systems. The measuring absorbance (detection of reflectance) of the separated substances was carried out “in situ” at 296 nm using 4-level calibration (external standard, nonlinear regresson function) in the concentration range 600–1200 ng 2-aminopyridine/spot and 300–600 ng DP-I and DP-II/spot. The HPLC method was carried out using RP-8 stationary phase and methanol + phosphate-citrate buffer, pH 3 mobile phase with addition of sodium pentanesulfonate (40+60, v/v). 2-aminopyridine wass detected at 300 nm, DP-I at 280 nm and DP-II at 248 nm. The concentration range for 2-aminopyridine is 2–40 μg/ml, for DP-I and DP-II 2–20 μg/ml (for an injection volume of 10 μl). The results were evaluated by linear regression analysis.
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    Chiral bonded packings for liquid chromatography: Preparation and evaluation of N-acylated aminoacid packings based on aminopropylated silica gel (1989)
    Springer
    Chromatographia 28 (1989), S. 212-216 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral bonded phases ; Enantiomer separations ; Amino acid esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary N-Protected single amino acid residues have been chemically bound to aminopropylated silica gel to give chiral HPLC column packings. Surface coverages have been determined by both elemental and aminoacid analyses. In addition, the nature of the surface-bound groups has been studied by reflectance fourier transform infrared (FTIR) spectroscopy. The resolution of a range of racemic mixtures has been achieved using the column packings.
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    URL: http://dx.doi.org/10.1007/BF02319650
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    Enantiomerization during HPLC on an optically active sorbent. Deconvolution of experimental chromatograms (1989)
    Springer
    Chromatographia 28 (1989), S. 263-266 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Triacetylcellulose ; Enantiomer interconversion ; Deconvolution of chromatograms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The enantiomers of 1,3,7-trimethylbenzo[c]phenanthrene, a chiral helicene hydrocarbon, are separated on triacetyl-cellulose but interconvert during HPLC. Column temperatures were between 2 and 22°C and linear velocities between 0.3 and 1.2 mm s−1. Simultaneous photometric and polarimetric detection resulted in deconvoluted experimental chromatograms, showing the relative concentration of each of the enantiomers as aseparate function of the retention volume. The use of deconvoluted chromatograms for determining rate constants of enantiomerization is discussed. It is of interest that the rate constant at 22.3°C in solution, i.e. in the absence of a sorbent, has been obtained by an independent method: stopped-flow monitoring of racemization after HPLC on triacetylcellulose.
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    The effect of an organic eluent modifier and pH on the separation of wheat-storage proteins: Application to the purification of γ-gliadins ofTriticum monococcum L (1989)
    Springer
    Chromatographia 28 (1989), S. 133-138 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Wheat proteins ; γ-gliadins ; Effect of pH on separation ; Effect of organic modifier on separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase, high-pressure liquid chromatography has been used to separate similar protein (γ-gliadin) components from 70% ethanol extracts of endosperm flour from two different accessions of the diploid wheatTriticum monococcum L. The effect of acetonitrile as the organic eluent was compared to acetonitrile: 2-propanol (3:1) at two different pH's. Conditions for maximum resolution of the γ-gliadin components were found to be at pH 7.2 with acetonitrile: 2-propanol (3:1) as the eluent. These conditions allowed the components to be obtained in sufficient purity for further charaterization.
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    Selective preconcentration on a metal loaded silica precolum and on-line HPLC separation of catechol derivatives in a complex medium. Application to the analysis of catecholamines in urine (1989)
    Springer
    Chromatographia 28 (1989), S. 459-464 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Catecholamines in urine ; Liquid-solid extraction ; Metal-loaded silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of iron loaded silica to selectively preconcentrate, by a chelating effect, catechol and its derivatives has been investigated. Parameters which can influence the breakthrough volume, such as minimum saturation concentration, variation of pH, ionic strength and flow rate of the preconcentrated phase are described. The coupling of this method with an ion-pairing chromatographic separation is demonstrated, several eluting solutions have been investigated. The influence of elution times, the linearity, the limit of detection and the recovery of the system are studied. This method has been applied to the quantitative determination of catecholamines in urine samples using 1,2-dihydroxybenzylamine as an internal standard.
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    Optical resolution HPLC column packings carrying penicillin sulfoxide nucleus. Part I. Polymer synthesis and resolution efficiency (1989)
    Springer
    Chromatographia 28 (1989), S. 505-508 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Optical resolution ; Polymeric adsorbents ; Penicillin sulfoxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polyacryl or methacrylamides bearing penicillin sulfoxide skeleton were synthesized. The obtained polymers were coated onto macroporous silica gel and the properties of the prepared packings were investigated. The column packing comprising poly(benzyl 1-oxo-6-methacrylaminopenicillanate) was found to resolve various aromatic racemates.
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    Optical resolution HPLC column packings carrying penicillin sulfoxide nucleus. Part IV. Effect of substituents in the benzyl ester group on the optical resolution efficiency (1989)
    Springer
    Chromatographia 28 (1989), S. 513-515 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Optical resolution ; Polymeric adsorbents ; Penicillin sulfoxide ; Substituent effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fourteen new vinyl polymers carrying penicillin sulfoxide nucleus, poly (substituted-benzyl 1-oxo-6-metha-crylaminopenicillanate)s, were synthesized in order to investigate the influence of the substituents on the optical resolution capabilities. The resolution efficiency of the high-performance liquid chromatography columns comprising the obtained polymers were examined usingtrans-stilbene oxide and N-acetyl-1-phenethyl-amine. It was found that some columns resolved both racemates, some one, while the others did not separate either. A polymer which has 2,6-dichlorobenzyl moiety was found to resolve both racemates more effectively than the unsubstituted polymer.
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    High-performance liquid chromatographic resolution of enantiomers on chiral epoxy polymer-coated silica gel (1989)
    Springer
    Chromatographia 28 (1989), S. 477-480 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phase ; Resolution of amino acid derivatives ; Enantioseparation by HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A chiral stationary phase for the separation of some D-and L-amino acid derivatives using a new resolving agent is described. The enantiomeric resolution was accomplished by normal phase high-performance liquid chromatography. The support was easily prepared by coating an epoxy polymer of L-valinamide on aminopropylsilanized macroporous silica. The influence of subambient temperatures on the enantioselectivity was also examined.
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    Optical resolution of 2-hydroxy acids by high-performance ligand exchange chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 481-486 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand exchange ; Chiral phase ; Optical resolution of 2-hydroxy acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Using an MCl GEL CRS10W column, which was packed with octadecyl silica (ODS) coated with N,N-dioctyl-L-alanine, optical resolution of 2-hydroxy acids was performed. The optical resolution of mandelic acid derivatives and C2 to C5 2-hydroxy acids was carried without any pretreatment. The MCl GEL CRS10W column could resolve amino acids and 2-hydroxy acids. For their selective detection, a post-column method was employed in which the specific color reaction of 2-hydroxy acids with iron(III) ion was utilized. For the analysis of foodstuffs, in which amino acids and 2-hydroxy acids often coexist, the present method was found to be effective in distinguishing between these enantiomers.
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    Isolation and quantitative analysis of hydroxylysine glycosides (1989)
    Springer
    Chromatographia 28 (1989), S. 497-501 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Collagen metabolites ; Amino acid derivatives ; Glycosides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Methods are described for the isolation of galactosyl hydroxylysine and glucosylgalactosyl hydroxylysine from collagen and for the quantitative analysis of these hydroxylysine glycosides. The isolation procedure, based upon gel filtration and preparative ionpaired reversed-phase high-performance liquid chromatography, is simple and rapid in comparison with existing methods, allowing the production of tens of milligrams of each glycoside in a single day. Quantitative analysis of the hydroxylysine glycosides is effected by reversed-phase high-performance liquid chromatography with precolumn derivatization (usingo-phthal-dialdehyde) and fluorescence detection.
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    A practical description of retention in reversed phase chromatography using four parameters (1989)
    Springer
    Chromatographia 27 (1989), S. 5-14 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention behaviour ; Column parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention of small molecules on reversed phase or other hydrophobic stationary phases can be represented by k′ values of members of a homologous series at varying solvent compositions. The evaluation of simple linear relationships leads to the introduction of a set of four parameters that contain all the information about retention behaviour of this homologous series in the binary solvent system chosen. It is possible to extrapolate to a hypothetical non-hydrophobic molecule and a solvent, the polarity of which equals that of the stationary phase, to characterize the properties of the stationary phase — eluent system. In addition, a chromatographic method for determination of the phase ratio of the column is proposed.
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    Energy calculations and computer modeling of chromatographic separations on microcrystalline cellulose triacetate (1989)
    Springer
    Chromatographia 27 (1989), S. 77-81 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microcrystalline cellulose triacetate ; Molecular modeling ; Computer graphics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Molecular modeling and energy calculations have been used to study the chromatographic separation of aromatic compounds on microcrystalline cellubose triacetate. A linear relationship has been found between the logarithms of the capacity factors and the energy values of the interaction of these compounds with this stationary phase. The interaction energies have been calculated for two different spatial dispositions of the solutes in relation to the sorbent.
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    A chemically bonded liquid crystal as a stationary phase for high performance liquid chromatography. Synthesis on silica via an organochlorosilane pathway (1989)
    Springer
    Chromatographia 27 (1989), S. 559-564 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Liquid crystals ; Synthesis of new bonded phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A compound which becomes a liquid crystal when bonded to a polysiloxane was reacted with dimethylchlorosilane to produce a reagent suitable for bonding to a silica surface. After the silanization reaction was complete, the product was characterized by elemental analysis, diffuse reflectance Fourier transform Infrared Spectroscopy (DRIFT), CP/MAS carbon-13 NMR and differential scanning calorimetry (DSC). Preliminary chromatographic testing was done by retention index measurements using the alkylarylketone homologous series and by measuring the separation factor, α, for anthracene/phenanthrene at two different mobile phase compositions.
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    Preparative medium pressure liquid chromatographic (MPLC) and semipreparative HPLC separation of furocoumarin isomers (1989)
    Springer
    Chromatographia 27 (1989), S. 591-595 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Overpressured layer chromatography ; Furocoumarin isomers ; Preparative separation of plant extracts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Preparative medium pressure liquid chromatography and semi-preparative high performance liquid chromatography on silica were employed for the isolation of eight furocoumarin isomers (iso-bergapten, angelicin, psoralen, bergapten, pimpinellin, sphondin, xanthotoxin and isopimpinellin). The conditions were transposed from analytical on-line overpressured layer chromatography and analytical high performance liquid chromatography, respectively. The retention data of the analytical on-line overpressured layer chromatographic separation and the preparative medium pressure liquid chromatographic isolation show a linear relationship. Using 15 μm TLC silica 60 as stationary phase a dry-packing procedure aas developed for labomatic medium pressure liquid chromatographic glass columns. The efficiency of the preparative separation techniques was demonstrated by the isolation of the investigated furocoumarins from Heraclei mantegazziani radix and from Pimpinellae radix (Balkan quality).
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    Prediction of HPLC retention times in gradient elution from isocratic data application to a set of non-homologous compounds and different stationary phases (1989)
    Springer
    Chromatographia 27 (1989), S. 19-23 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Prediction of retention times ; Gradient elution ; Substituted quinolines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A chromatographic model able to predict, from experimental isocratic data, retention times of solutes under gradient conditions has been proposed previously. The prediction was shown to be totally independent of the chemical properties of both solutes and eluents. In order to further check the general validity of the theory, the model has now been applied to a nonhomologous set of compounds, namely a range of substituted quinolines (methyl-, hydroxy- and amino-) and several different stationary phases. Results show a dependence on the stationary phase and, to a lesser extent, on the chemical structure of the solutes. The possible sources of errors are discussed. The generality of the method holds, within acceptable limits, if predictions concern the same type of stationary phase.
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    The case of the elusive tm values in HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 156-158 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mobile phase retention time ; Capacity factor ; Negative capacity factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Numerous ideas and procedures have been suggested in the literature for the determination of tm, the retention time of a non-retained species, in high-performance liquid chromatography. In some cases chromatograms have been obtained showing sample components eluting prior to the assumed non-retained species. This phenomenon results in apparent negative capacity factors for the species in question. We have proposed a method employing small inorganic anions which results in a limiting value for tm and eliminates apparent negative capacity factors.
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    Analysis of thiols by HPLC after fluorescent prelabelling with 4-(6-methylnaphthalen-2-yl)-4-oxobuten-2-oic acid (1989)
    Springer
    Chromatographia 27 (1989), S. 185-190 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiol analysis ; Fluorimetric detection ; Derivatization with 4-(6-methylnaphthalen-2-yl)-4-oxobuten-2-oic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of 4-(6-methylnaphthalen-2-yl)-4-oxobuten-2-oic acid as a fluorogenic reagent in pre-column derivatization for the high-performance liquid chromatography (HPLC) of biologically important thiols (L-cysteine, glutathione, N-acetylcysteine, homocysteine and mercaptopropionylglycine) was investigated. The aroylacrylic acid reacts selectively and rapidly (15 min. at room temperature) with the thiol compounds to give stable fluorescent adducts which can be separated by reversedphase HPLC and detected fluorometrically (λex 300nm); λem 445nm). The experimental conditions for the thiol derivatization and chromatographic separation are discussed. Applications to the determination of N-acetylcysteine, mercaptopropionylglycine and cysteine are described.
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    Retention behaviour of selected flavonoid compounds in NP-HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 625-627 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Normal phase elution ; Silica and cyano columns ; Flavonoid compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC retention data for a number of flavonoid compounds have been evaluated on normal phase silica and cyano colums according to the Soczewinski-Snyder (S.-S.) model. On the silica phase most of the flavones examined exhibited asymetrical peak shapes indicating strong and mixed retention mechanisms; on the cyano phase the intercept of the S.-S. relationship was independent of any hydroxy substitution pattern or of molecular planarity. A similar behaviour, but with different intercept values, was observed with coumarin and quinone compounds.
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    Preparative HPLC of carotenoids (1989)
    Springer
    Chromatographia 27 (1989), S. 325-327 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carotenoid ; Xanthophyll ; Broccoli ; Paprika
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the preparative HPLC of up to 50mg of carotenoid using a self-packing axially-compressed column. Oxygenated carotenoids, xanthophylls, are separated with silica as the stationary phase and acetone/petroleum ether as the mobile phase, while carotenes are separated using magnesium oxide/polyamide as the stationary phase and undiluted petroleum ether as the mobile phase.
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    Applications of HPLC with evaporative light scattering detection in fat and carbohydrate chemistry (1989)
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    Chromatographia 27 (1989), S. 340-342 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Evaporative light scattering detection ; α, ω-Dicarboxylic and hydroxycarboxylic acids ; Alkylglucosides and glycerides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The advantages of an evaporative light scattering detector in HPLC are demonstrated using the separation of α, ω-dicarboxylic and hydroxycarboxylic acids, alkyl glucosides and mono-, di- and triglycerides as examples. By using this detector reversed phase as well as normal phase gradient HPLC becomes possible for substances with no UV absorption.
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    Preparation of silica-based cation-exchangers for use in ion chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 316-320 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Silica-based cation-exchanger ; Trimethylsilyl chlorosulfonate ; Lanthanides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A low exchange-capacity, silica-based cation-exchanger for use in ion chromatography has been synthesized. (p-Trimethylsilyl)benzyl-dimethylchlorosilane (TBDCS) reacts with trimethylsilyl chlorosulfonate (TMCS) to produce a compound sulfonated in the para position of the type ArSO2OSi (CH3)3, which is bonded to 5 μm porous silica beads and hydrolysed to the corresponding arylsulfonic acid. The product is hydrophilic and has a high degree of sulfonation, efficiencies of packed columns reaching about 40,000–50,000 plates per meter for the separation of the Mn2+ ion. The new stationary phase has been applied to the ion chromatography of some organic and inorganic ions. It is notable that 14 lanthanides can be separated by isocratic elution about one hour on a 150×4·6 mm column, with 4 mM ethylenediamine and 6 mM α-hydroxyl-isobutanoic acid (pH 3.67) as mobile phase.
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    Enhanced chemiluminescence detection of some dansyl amino acids in liquid chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 191-193 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dansyl amino acids ; Chemiluminescence ; Bis(2,4,6-Trichlorophenyl)oxalate, (TCPO) ; Enhancement of luminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The dansylated amino acids alanine, glutamic acid, methionine and norleucine were separated by reversedphase HPLC and detected via chemical excitation using the post-column, TCPO-peroxyoxalate reaction system. Enhancement of the chemiluminescence emission was achieved by including the surfactant Triton X-100 in the eluent.
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    Measurement of elastin hydrolysis by reverse-phase HPLC with on-line post-colum derivatization (1989)
    Springer
    Chromatographia 27 (1989), S. 225-227 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reverse-phase chromatography ; Elastin Hydrolysis measurement ; On-line post-column derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Excessive breakdown of elastin, a structural protein, may be related to aortic disease and emphysema. Since L-valyl-L-proline occurs in high concentrations in elastin, a rapid and sensitive method using HPLC with post-column on-line derivatization was used to measure the dipeptide from swine aortic tissue, and the amount of elastin present was determined. Elastin was extracted by alkaline hydrolysis. After neutralization and filtration, the sample was injected onto a ODS-2 gel column, and the dipeptide was eluted by a linear gradient of 0 to 10% of 1-propanol in 50 mM heptafluorobutyrate, pH 3, at a flow rate of 1 ml/min. The eluent was reacted with fluorescamine at pH 8.6, and fluorescence was detected at an excitation wavelength of 395 nm and a 455 nm cutoff emission filter.
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    Anion exchange behaviour of hydrous titanium oxide and its use for column separations (1989)
    Springer
    Chromatographia 27 (1989), S. 472-474 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydrous titanium oxide ; Anion exchange ; Polyvalent anions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Hydrous titanium oxide (HTiO), prepared under varying conditions of precipitation, has been studied for its anion exchange behaviour. Its chemical and thermal stability has been examined. The stoichiometry of uptake for Cl− has been investigated using a36Cl radiotracer and the regeneration power of the exchanger checked. Distribution coefficients for halides and polyvalent anions have been determined and on the basis of sorption data some polyvalent anions have been separated using HTiO columns.
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    An improved HPLC determination of flavonoids in medicinal plant extracts (1989)
    Springer
    Chromatographia 27 (1989), S. 509-512 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flavonoids ; Crataegus ; Passiflora ; Matricaria ; Ginkgo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Flavonoids of Crataegus monogyna, Passiflora incarnata, Matricaria chamomilla and Ginkgo biloba extracts have been separated by isocratic elution on C18 columns using eluents based on C3 alcohols, tetrahydrofuran or dioxane. Satisfactory results have been obtained at compared to the low resolution achieved with the customary system acetonitrile-water-acetic acid.
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    Chromatography based on membrane separation with vesicular packing material (1989)
    Springer
    Chromatographia 28 (1989), S. 561-564 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size exclusion ; Vesicular packing material ; Proteins and polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new vesicular packing material — prepared from plant cell clusters by purification of the intact cell wall framework —is suitable for chromatography, giving high performance at low pressure gradients. The separation is achieved by dialysis through the cell wall, which is an ultrafilter membrane with an extremely sharp size limit of separation. Almost the whole of the stationary liquid phase is located within the vesicle (empty cell) lumina. In contrast to gel filtration vesicle chromatography gives a practically ideal separation of two size groups with an extremely short fractionation range. The size limit of separation was investigated by chromatography of proteins and other polymers. Group separation of molecules of a polydisperse dextran standard preparation showed that the critical Stokes' diameter for dextran permeation into the stationary liquid phase of the vesicular packing is 5 to 6 nm.
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    URL: http://dx.doi.org/10.1007/BF02260677
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    Semi-preparative high-performance liquid chromatographic separation of four 1.1-dimethylethyl 4- and 5-bromo-trans-2-methylcyclohexane-1-carboxylate isomers (1989)
    Springer
    Chromatographia 28 (1989), S. 585-587 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparative scale separation ; 1,1-Dimethylethyl 4- and 5-bromo-trans-2-methylcyclohexane-1-carboxylate ; Trimedlure-related isomers ; Ceratitis capitata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A semi-preparative high-performance liquid chromatographic procedure on 5-μm silica was developed for the isolation of gram quantities of four 1,1-dimethylethyl 4- and 5-bromo-trans-2-methylcyclohexane-1-carboxylate isomers (trimedlure-related) for NMR studies and comparative biological evaluation as male medfly,Ceratitis capitata, attractants.
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    URL: http://dx.doi.org/10.1007/BF02260682
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    Applications of chromatographic and spectrometric techniques to the study of dexamethasone related compounds (1989)
    Springer
    Chromatographia 28 (1989), S. 623-630 
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    ISSN: 1612-1112
    Keywords: Thin-layer chromatography ; Column liquid chromatography ; Dexamethasone related compounds ; Mass spectrometry ; Illicit drug formulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A methodology for the analysis of dexamethasone and related compounds is proposed. Nine corticoids (corticosteroids) have been separated by TLC and by normalphase HPLC. The optimization of the HPLC separation is performed on a diol column and with a n-hexane/isopropanol (80:20) mobile phase. Mass spectrometry is used to elucidate the nature of the compounds isolated from illicit drug formulations and to confirm the structure of synthesised derivatives from the parent dexamethasone.
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    URL: http://dx.doi.org/10.1007/BF02260691
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    Nucleotide and aldehyde analysis by HPLC for determination of radical induced damage (1989)
    Springer
    Chromatographia 28 (1989), S. 65-68 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Oxygen radicals ; Nucleotides ; Aldehydes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The analysis of two metabolite groups, nucleotides and aldehydes, is necessary for assessment of oxygen radical metabolism during hypoxia and reoxygenation. Nucleotides and their derivatives were determined by HPLC using gradient elution with 10 mM NH4H2PO4 buffer containing 2 mM t-butylammoniumphosphate and acetonitrile. Aldehydes occuring after lipid peroxidation were analyzed by derivatisation to dinitrophenylhydrazones followed by TLC and HPLC separation with methanol/water on an ODS column.
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    Requirements and tests for HPLC apparatus and methods in pharmaceutical quality control (1989)
    Springer
    Chromatographia 28 (1989), S. 85-88 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Quality assurance ; Pharmaceutical analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary One possible method has been demonstrated for pharmaceutical quality control which is not restricted to this field and fulfils and documents the prerequisites for reliable, accurate and precise HPLC analysis. This includes validation which shows that the method is able in principle to fulfil the requirements, the apparatus test which shows that the apparatus generally works correctly and precisely and the system suitability test which shows that the method provides accurate and precise results on this apparatus and with this column for the analysis in question when other non-equipment and non-method-induced errors are excluded.
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    Immobilized enzymes as chromatographic phases for HPLC: The chromatography of free and derivatized amino acids on immobilized trypsin (1989)
    Springer
    Chromatographia 28 (1989), S. 551-555 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separations ; Trypsin on silica ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new HPLC stationary phase was synthesized by the covalent immobilization of the enzyme trypsin (TRYP) on silica. The hydrolytic activity of the immobilized enzyme was 72% of the activity of an equivalent molar amount of free TRYP. The initial chromatographic studies indicate that this phase can be used for chiral separations of enantiomeric O- and N,O-derivatized amino acids which are natural substrates on TRYP and that the stereochemical resolutions are a result of the activity of the enzyme.
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    Effect of destruction of chemically bonded reversed phases by hexamethyldisilazane during end-capping (1989)
    Springer
    Chromatographia 28 (1989), S. 574-578 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phases ; End-capping ; Destructive effects on bonded phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMS) have been used as a secondary deactivation (end-capping) reagents for packing materials for RP HPLC. Three types of chemically bonded phases (CBP) with different structures and different coverage densities were used. The destructive effects of HMDS on the coverage density of chemically bonded C18 and C8 phases is discussed.
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    Assay for methylnaltrexone in rat brain regions and serum by high-performance liquid chromatography with coulometric electrochemical detection (1989)
    Springer
    Chromatographia 28 (1989), S. 359-363 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Coulometric electrochemical detection ; Methylnaltrexone ; Rat brain and serum analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and sensitive method is described for the determination of methylaltrexone, a quaternary narcotic antagonist, in discrete rat brain regions and serum. Separation and quantitation are performed by reversedphase high-performance liquid chromatography with coulometric electrochemical detection. Perchloric acid extracts of the brain tissue or serum were passed through a normal-phase solid-phase extraction CN column, and methylnaltreexone was subsequently eluted with a mixture of absolute ethanol and 25mM trifluoroacetic acid. Methylnaltrexone gave a linear response over the range of 12.5–100ng in 1.0ml for cerebellar homogenates and 25–200ng in 50μl for serum. The average betweenassay coefficients of variation for methylnaltrexone from 1.0ml of cerebellar homogenate and 50μl of serum were 5.2 and 3.6%, respectively, over the concentration range studied. The within-assay coefficients of variation at 12.5ng/ml cerebellar homogenate and 25ng/50μl for serum were 7.4 and 4.6%, respectively. Analytical recovery of methylanyltrexone, added to cerebellar homogenate and serum samples, were 85 and 89%, respectively. The method was applied to the analysis of methylnaltrexone in discrete rat brain regions and serum after intraperitoneal injection.
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    Preparative scale reversed-phase HPLC method for simultaneous separation of carotenoids and carotenoid esters (1989)
    Springer
    Chromatographia 28 (1989), S. 129-132 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carotenoids ; Paprika, Rose hips, Marigold
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the preparative HPLC of carotenoids and carotenoid esters using a self-packing axially-compressed column. The reversed-phase system used employs an RP-18 stationary phase and a mobile phase consisting of a mixture of petroleum spirit, acetonitrile, methanol and tetrahydrofuran. The method is demonstrated for paprika fruit, rose hips and marigold flowers.
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    Retention characteristics of aliphatic compounds on cellulose acetates as a stationary phase with an aqueous mobile phase (1989)
    Springer
    Chromatographia 28 (1989), S. 279-284 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cellulose acetate ; Acetyl content ; Temperature effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Cellulose and cellulose mono-, di-, and triacetate were used as stationary phases for liquid chromatography with water as a mobile phase, and the retention behavior of alcohols, ethers, ketones, and chlorides was examined. For cellulose acetate columns, the logarithm of the specific retention volume, (logV g * ), correlated linearly with the logarithm of partition coefficient between 1-octanol and water (log Ko/w), for each homologous group, but all solutes were unretained on cellulose columns. With the exception of chlorides, the intercept values of the log V g * –log Ko/w regression lines increased significantly with increase of acetyl content of cellulose acetates, but the slopes of the regression lines changed little. This suggests that hydrophobic interaction between the acetyl groups of cellulose acetates and the alkyl chains of the solutes is the dominant factor in the retention. The capacity factors for 1-alcohols with cellulos diacetate column indicated a maximum at a column temperature of about 40°C. This unique retention behavior was assumed to be caused by small structural change of the cellulose acetate polymer, because this temperature effect on the retention corresponded with effects observed by differential scanning calorimetry (DSC).
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    Chromatographic investigations of furocoumarins fromHeracleum genus fruits (1989)
    Springer
    Chromatographia 28 (1989), S. 161-166 
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    ISSN: 1612-1112
    Keywords: Thin-layer chromatography ; Column liquid chromatography ; Micropreparative separations ; Furocoumarins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Furocoumarins from extracts ofHeracleum genus fruits were separated using normal and reversed phase TLC and HPLC and isolated in the milligram scale using overloaded systems of column chromatography. Binary or ternary solvents containing a polar modifier (methanol, diisopropyl ether or acetonitrile) were used as the mobile phases.
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    Influence of mobile phase composition on the adsorption of hen egg-white proteins to anion-exchange cellulose (1989)
    Springer
    Chromatographia 28 (1989), S. 170-178 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange ; Mobile phase optimisation ; Egg-white proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Factors influencing the capacity of Whatman QA52 anion-exchange cellulose for hen egg-white proteins have been investigated. While simply increasing the concentration of protein in the feedstock increases the loading there is a concomitant reduction in binding efficiency in a single pass through the column. Substitution of buffer by water in the mobile phase during sample preparation, thereby reducing the ionic strength of the feedstock, had the effect of significantly increasing protein capacity whilst improving binding efficiency. During column loading large changes in pH of the mobile phase were observed although this had no apparent effect on the chromatography for this system.
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    A chromatographic method for hydrophobicity investigations of sorbents (1989)
    Springer
    Chromatographia 28 (1989), S. 258-262 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded stationary phases ; Evaluation of the hydrophobicity of sorbents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The energy of interaction (∈0) between the methylene group and the surface of a sorbent is proposed for use in the quantitative evaluation of the hydrophobicity of a sorbent. A method was developed to determine the ∈0 parameter from chromatographic measurements using the investigated sorbent as the stationary phase and linear methylene-containing homologous series, e.g., alkanols, amino-alkanes, etc., as the test compounds. The effectiveness of this method is demonstrated by using, as examples, a series of bonded stationary phases and a series of cross-linked copolymeric sorbents differing in the concentration of the hydrophobic groups. The proposed method is compared with the Martin rule used extensively in the chromatography of oligomers.
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    Computer-assisted transposition of conditions in high-performance thin-layer chromatography to high-performance liquid chromatography for the separation of pesticides (1989)
    Springer
    Chromatographia 28 (1989), S. 285-288 
    Details
    ISSN: 1612-1112
    Keywords: Thin-layer chromatography ; Column liquid chromatography ; Mobile phase optimization ; HPTLC transposition to HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A computer-assisted method is presented for mobile phase selection for the optimal separation of pesticides by HPTLC and HPLC. The system is based on a plot of solute retention value and separation criterion vs. binary mobile phase composition for graphic optimization. The result of HPTLC can be transposed to HPLC for optimal separation. The transposition equation is given.
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    HPLC determination of the flavonoid glycosides fromBetulae folium extracts (1989)
    Springer
    Chromatographia 28 (1989), S. 311-312 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flavonoid glycosides ; Betula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The main flavonoid glycosides ofBetulae folium extracts (quercetin-3-glucuronide, myricetin-3-galactoside, hyperosid, quercetin-3-arabinoside and quercetin-3-rhamnoside) have been separated by isocratic elution on a C18 Aquapore RP-300 column. Elution was performed with 17% isopropanol at pH 6.2 confirming the validity of this eluent for the analysis of the flavonoid glycosides.
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    Precolumn fluorogenic labelling of carboxylic acids with the use of N-(1-pyrenyl)-bromoacetamide and phase-transfer catalysis (1989)
    Springer
    Chromatographia 28 (1989), S. 367-369 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carboxylic acids ; Fluoregenic esterification ; Phase-transfer catalysis ; Ion pairing ; N-(1-Pyrenyl)-bromoacetamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary N-(1-Pyrenyl)-bromoacetamide, which is readily synthesized from 1-aminopyrene and bromoacetyl bromide, has proved to be an excellent derivatization reagent for carboxylic acids. A technique has been developed, based upon a reaction with the carboxylate as an ion pair in ethylene dichloride at 90 °C, which gives highly fluorescent ester derivatives, permitting quantitative determination by liquid chromatography of less than one pmol using conventional fluorimetric detection. Further, the method is highly reproducible and of general utility.
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    Application of diode array detectors for solute identification in toxicological analysis (1989)
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    Chromatographia 28 (1989), S. 341-353 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Diode array detectors (DAD) ; Toxicology ; Automated solute identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The possibilities and limitation of automated solute identification via UV/VIS spectroscopy in HPLC are demonstrated and applications in toxicologic analysis are described. A standard isocratic system is used. The influence of various chromatographic parameters on retention time is shown. A retention time window of ±15% is required. In addition to retention time, derived spectral data are calculated (minima and maxima of derivatives, area counts under standardized spectral ranges, absorption at various wavelength) and used for positive solute identification. It is possible to identify solutes with a high degree of certainty in urine and plasma if their concentration is at least 10 ppm.
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    A chromatographic analysis of hindered diffusion of saccharides in silica gels (1989)
    Springer
    Chromatographia 28 (1989), S. 370-374 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Diffusion coefficients ; Distribution coefficients ; Dextran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic technique as a means for experimental studies of diffusion in porous solids has been demonstrated. In this paper we report the effective diffusion coefficients which we have chromatographically obtained for two dextran samples and three low molecular weight solutes. The chromatographic method of measuring diffusional resistances in porous solids has the advantages of rapidity and simplicity. This method also provides information on the axial dispersion and distribution of a solute between the moving phase and the solvent held stationary in the pore. The elution curves of a packed column in pulse response experiments were analyzed by the method of moments to give the parameters of interest. The results indicate that pore diffusion of the solutes was appreciably restricted in comparison with diffusion in bulk solution. The degree of hindrance depended on the size of the diffusing substances.
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    The effects of buffer salt concentration on the HPLC retention of nucleic acid components (1989)
    Springer
    Chromatographia 28 (1989), S. 493-496 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nucleic acid components ; Buffer salt concentration ; Variation of retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In the reversed-phase high-performance liquid chromatographic studies of nucleotides, nucleosides and bases, phosphate and acetate are commonly used as buffer materials. The concentration of these buffer salts in the mobile phase exerts noticeable influence both upon the retardation and upon the separation of the nucleic acid components. This can be of certain usage in the fine adjustment of the elution order of individual components. The possible reasons for the observed data are discussed.
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    Separation of metal acetylacetonates by reversed-phase high-performance liquid chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 519-522 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase chromatography ; Separation of metal acetylacetonates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Using reversed-phase high-performance liquid chromatography acetylacetonate complexes with trivalent metals such as Al(III), Co(III), Cr(III) and Fe(III) have been examined in columns containing RP-2, RP-8 and RP-18 bonded phases. The mobile phase consisted of acetonitrile/water or methanol/water mixtures with various compositions. As shown the order of elution of the acetylacetonates depends on the type of the column packing and on the nature and concentration of the organic modifier in the mobile phase.
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    Purification of human chorionic gonadotropin hormone by anion-exchange high-performance liquid chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 601-604 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion exchange separation ; Preparative separations ; Human chorionic gonadotropin hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatography (HPLC) method was developed for the purification of 50mg crude human chorionic gonadotropin (HCG) hormone sample in one chromatographic run on a 250×10 mm SERVA DEAE Poliol-Si-500 column. During the 60-minute linear gradient of 0.05 M sodium sulfate, 0.05 M sodium hydrogen sulfate and 0.05% (v/v) acetonitrile in buffer “B” complete separation was accomplished in 40 min. Identity and purity of the fractions were checked by SDS electrophoretic method. The eluted HCG fractions were dialyzed for 24 hours to remove the buffer salts and liophilized. The activity of the hormone did not decreased significantly during the purification procedure.
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    Physico-chemical applications of HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 633-638 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Adsorption isotherms ; Equilibria criteria ; Silica and carbon adsorbents ; Aromatic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Examples of high-performance liquid chromatography (HPLC) are given for the determination of adsorption equilibrium and distribution coefficients, calculation of excess adsorption isotherms from solutions ranging from 10−7 to 10−1 mole fraction, changes in activity coefficient of the component predominantly adsorbed from solution and substitution enthalpy. These examples stem from studies of HPLC and the static adsorption of benzene, anisole and benzaldehyde from solutions in n-heptane on macroporous silica and active carbon at various temperatures. A criterion is suggested for evaluating equilibrium in the HPLC process. The potential of size-exclusion chromatography (SEC) for evaluating the volume and predominant diameter of adsorbed pores as well as pore diffraction are discussed. Prospects for HPLC application to molecularstructural analysis and other purposes are discussed briefly.
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    The use of large polycyclic aromatic hydrocarbons to study retention in non-aqueous reversed-phase HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 118-122 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase chromatography ; Non-aqueous reversed-phase chromatography ; Polycyclic aromatic hydrocarbons ; Solvent strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Elution strengths of 11 common HPLC solvents on a polymeric C18 phase were compared using a marker set of polycyclic aromatic hydrocarbons. Naphthalene, pyrene, benzo[ghi]perylene, and three larger naphthologues of 8, 10, and 12 rings (constituting a “naphthalene zigzag” series) were chosen because they span the solvent strength range up to and including the strongest solvents, tetrahydrofuran (THF) and chlorobenzene. Four pairs of similarly shaped isomers were used to probe solvent selectivity. With the exception of THF, HPLC solvent strength correlated with observed red shifts of fluorescence band maxima in each solvent. For THF, the pure solvent and blended mixtures behaved quite differently.
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    HPLC determination of catabolic amines in silage using their dansyl derivatives and an electrochemical detector (1989)
    Springer
    Chromatographia 27 (1989), S. 216-220 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detector ; Amines ; Silages ; Feedstuffs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of the electrochemical detector (EC) in the high performance liquid chromatography (HPLC) of dansyl derivatives of biogenic amines is reported. Isocratic and gradient elution patterns of synthetic mixtures of putrescine, cadaverine, 1,6-diaminohexane, tryptamine, histamine, tyramine, spermine and spermidine on a reversed phase column are shown. Hydrodynamic voltammograms of standard compounds are presented. The detection limits of the EC are compared with those of ultraviolet and spectrofluorimetric detectors. A chromatographic profile of amines from the proteolytic catabolism of maize silage byClostridia is shown.
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    Equilibrium structures of the Arg-aldehyde moiety upon HPLC of peptides (1989)
    Springer
    Chromatographia 27 (1989), S. 228-232 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase ; 13C n.m.r. ; Arginine-aldehyde peptides ; GYKI-14166
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatographic and13C n.m.r. spectrometry methods were used for the investigation of peptides containing arginine-aldehyde moiety. Investigation of a model compound, N-benzoyl-Arg-H, showed that in an acidic mobile phase peptides containing the arginine-aldehyde group elute in three characteristic peaks. The components of the peaks were found to be constituents of an equilibrium mixture. The structures of the two components were identified, one as the aldehyde hydrate, the other as the cyclanol derivative. The reactivity of TRIS (HCl) buffer at pH 8.5 with the arginine aldehyde moiety was used for the assignment of the equilibrium structures.
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    Ion-pair reversed phase HPLC determination of nucleotides, nucleosides and nucleobases — Application to nucleotide metabolism in hepatocytes (1989)
    Springer
    Chromatographia 27 (1989), S. 639-643 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase ; Ion-pair ; Recoveries ; Hepatocytes ; Purine compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three groups of metabolites were analyzed in extracts of rat hepatocytes by an HPLC method: (i) nucleotides (ATP, ADP, AMP, GTP, GDP, UTP, UDP, IMP, UMP), (ii) nucleosides and nucleobases (adenosine, adenine, guanosine, inosine, xanthine, hypoxanthine, uridine) and (iii) inhibitors of xanthine oxidoreductase (oxypurinol, allopurinol). Perchloric acid extracts were neutralized with K2CO3/triethanolamine and analyzed at 254 nm by reversed-phase ion-pair high-performance liquid chromatography. The nucleotides and their derivatives were separated with a gradient elution using 10 mM NH4H2PO4/2 mM t-butylammonium-phosphate and acetonitrile. Recovery values were estimated for the extraction procedure used. The method was applied to the investigation of nucleotide metabolism of hepatocytes of starved rats at anoxia and reoxygenation.
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    URL: http://dx.doi.org/10.1007/BF02258995
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    High-performance liquid chromatographic determination of (−)-cathinone in plasma (1989)
    Springer
    Chromatographia 27 (1989), S. 201-204 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cathinone metabolites ; Plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography (HPLC) for the determination of (−)-cathinone in rabbit and human plasma has been studied. The problem of dimerization during extraction from plasma was satisfactorily resolved. Detection was by UV at 257 nm. Concentration levels as low as 24 ng ml−1 were satisfactorily determined. This level of sensitivity should be adequate for the detection of (−)-cathinone in the blood of khat users and also for the quantitative determination of (−)-cathinone in blood for pharmacokinetic purposes. The applicability of the assay procedure to pharmacokinetic studies is demonstrated.
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    URL: http://dx.doi.org/10.1007/BF02260446
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    A HPLC method for specific determination ofα-amylase and glucoamylase in complex enzymatic preparations (1989)
    Springer
    Chromatographia 27 (1989), S. 328-332 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glucose, maltose and maltotriose ; α-Amylase and glucoamylase ; Microfungal cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In the hydrolysis of soluble starch by mixtures of α-amylase and glucoamylase, the ratios maltose/glucose and maltoriose/glucose linearly depend, over a wide range, on the relation between both enzymes and are independent on the activity level of the enzymatic preparation. HPLC determination of hydrolysis products (glucose, maltose and maltotriose) of soluble starch by mixtures of these enzymes, after incubation under controlled conditions, is a rapid method for the evaluation of the relative levels of each enzyme in the mixtures. The method, first developed using pure commercial amylases, is applied, with consistent results, to cell free media ofAspergillus niger cultures on a glycogen-rich effluent.
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    URL: http://dx.doi.org/10.1007/BF02321279
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    A study of the practical limitations of principal components analysis and the labelling of unresolved HPLC peaks (1989)
    Springer
    Chromatographia 27 (1989), S. 343-358 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Principal components analysis (PCA) ; Iterative target transformation factor analysis (ITTFA) ; Peak labelling ; Chromatographic peak deconvolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The method of iterative target transformation factor analysis (ITTFA) used in conjunction with second derivative peak finding has shown to be a practical method for the peak deconvolution and reconstruction of HPLC chromatograms and spectra. The second derivative method of peak finding is acceptable for resolutions above 0.5 for peaks of similar heights. Above 0.5 resolution the labelling gives correct results where the spectra are substantially different and also when reasonably similar. Below this value the peak labelling was still accurate where the spectra were different. Solvent effects on the spectra of the compounds studied are small and do not hinder the peak labelling process. Thus small “local” libraries are feasible.
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    URL: http://dx.doi.org/10.1007/BF02321282
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    Separation and determination of nitrite ion by affinity chromatography with cyano(pheophytinato a)cobalt(III) charged column (1989)
    Springer
    Chromatographia 27 (1989), S. 461-464 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chlorophyll-bonded stationary phase ; Cyano(pheophytinato a)cobalt(III) ; Pheophytin a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation and determination of the nitrite ion by affinity chromatography is described. The good separation of the nitrite ion was obtained by using cyano-(pheophytinato a)cobalt(III) bonded octadecylsilica as the stationary phase and water of pH 4.3 adjusted by acetic acid as the mobile phase. Conventional ion chromatograph was also used for the analysis of the nitrite ion. For the synthetic samples prepared by mixing the nitrite and nitrate ions, analytical values obtained by affinity chromatography were in agreement with calculated values and close to the analytical values obtained by ion chromatography. In the proposed affinity chromatography, the nitrite and nitrate ions could be determined in the concentration range of 0.15–1.0ppm and 0.1–1.0ppm with relative standard deviations (n=10) of 5.3% and 4.7%, respectively.
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    URL: http://dx.doi.org/10.1007/BF02319564
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    Size exclusion chromatography on porous fractals (1989)
    Springer
    Chromatographia 27 (1989), S. 257-263 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size exclusion ; Fractal dimension ; Retention model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Some porous packings used in chromatography have been claimed to be fractals with a scale of sizes a〈l〈L, where a is a molecular size and L is the size of the largest pores. For a fractal porous packing, the excluded volume for molecules in solution in the vicinity of the packing surface is directly related to Df, the fractal dimension of the pore surface (2〈Df〈3). Since retention in size exclusion chromatography is itself directly related to this excluded volume, the fractal nature of the packing provides a model of retention in this technique. According to this model there is a linear relationship between log Rs and log(1-Kd), where Rs is the hydrodynamic radius of the solute macromolecules and Kd the distribution coefficient. The fractal dimension is derived from the slope of this plot. Size exclusion chromatographic retention data have been analyzed according to the model. It is found that some HPLC packings are fractals with fractal dimensions ranging from about 2.15 to 2.6, depending on the material. Such a large range of Df values indicates large variations in the selectivities and domains of applications of the different packings. For some classical gel filtration chromatographic gels, the fractal retention model does not seem to apply.
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    URL: http://dx.doi.org/10.1007/BF02260458
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    Simulation of peak profiles in non-linear HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 321-324 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Simulation of peak profiles ; Rouchon model ; LEA model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The possibilities and domain of applicability of the ideal chromatography model for calculating peak profiles in non-linear chromatography are analyzed. For this purpose we used the main conclusion of the model of a layer of equilibrium adsorption (LEA model), which determines the difference between ideal and non-ideal chromatography in terms of the relative length of a chromatographic column. It is shown that the experimental data of non-linear high-performance liquid chromatography can be approximated in terms of the elementary analytical relations known in the theory of ideal chromatography.
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    Direct determination of the racemate ratio of labetalol hydrochloride by HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 364-366 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Labetalol ; Separation of racemic diastereomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A direct, isocratic, reversed phase HPLC procedure is developed for the separation of the diastereomeric racemates of labetalol, a combined α- and β-adrenoreceptor antagonist. The aminoalcohol-type diastereomers were resolved on a C18 column using methanolwater-25% ammonia 27-75-2 mobile phase and detection at 220nm. The procedure is simple and convenient to carry out. The method may be of use in the determination of the individual diastereomeric racemates of labetalol in different forms such as bulk substance, pharmaceutical dosage preparations and biological fluids.
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    URL: http://dx.doi.org/10.1007/BF02321284
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    Correlation between retention and the C18 silica surface coverage in reversed-phase liquid chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 378-384 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phases ; Retention and surface coverage ; Phase ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Members of three homologous series and five non-homologous solutes with various functional groups were chromatographed on a series of well-characterized C18 reversed stationary phases with a range of methanol-water mobile phases. Measured capacity factors of solutes were correlated with the concentration of C18 ligands on the stationary phase. A linear relationship with the slope depending on a solute molecular structure and the volume fraction of methanol in the mobile phase was obtained. A method for the evaluation of phase ratio is also proposed.
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    URL: http://dx.doi.org/10.1007/BF02321287
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    Simultaneous flow rate and temperature programming based on computer-assisted retention prediction for the separation of PTH-amino acids in reversed-phase microcolumn liquid chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 417-424 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micro-columns ; Flow rate and temperature programming ; PTH amino acid derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of phenylthiohydantoin (PTH) amino acid derivatives by flow rate and temperature programming in reversed-phase micro-column liquid chromatography (LC) has been investigated. For both programming modes a microcomputer-assisted retention prediction system (REPRES) was constructed. The performance of this system has been evaluated by comparing actually measured retention data to those predicted. Excellent agreements between those data were found. It is clearly indicated that simultaneous flow rate and temperature programming can improve the separation of PTH-amino acids in reduced analysis time.
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    URL: http://dx.doi.org/10.1007/BF02319557
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    Normal-phase liquid and supercritical-fluid chromatographic separations of steroids with Fourier-transform infrared spectrometric detection (1989)
    Springer
    Chromatographia 27 (1989), S. 441-448 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Supercritical fluid chromatography ; Separation of steroids ; FTIR spectrometric detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary On-line FT-IR detection of a model mixture of steroids is performed for both SFC and HPLC. For HPLC, a conventional cyanopropyl bonded phase analytical-scale column and a highly crosslinked cyanopropyl microbore-scale column were used to separate the steroids. The latter, more deactivated column afforded no separation with the identical mobile phase. The SFC separation was carried out on crosslinked cyanopropyl bonded phase in a packed microbore column and 25% cyano-25% phenyl-50% methyl polysiloxane phase in a capillary column. It was seen that the order of elution of the steroids in both SFC and HPLC can be related to the number of hydroxyl groups present in the steroid molecule. On-line infrared spectra for each compound in both the liquid phase and the supercritical-fluid phase match well, with the carbonyl bands, slightly shifted to lower frequency in the liquid phase. Experiments are described which enable one to estimate the relative efficiency of various columns in several situations which are employed in this study.
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    High-performance liquid chromatographic determination of uric acid in feces of egg-laying hens (1989)
    Springer
    Chromatographia 27 (1989), S. 467-468 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Uric acid extraction ; Determination of uric acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method was developed for the determination of uric acid in the feces of egg-laying hens by high-performance liquid chromatography (HPLC), using a NovaPak C18 column and phosphate buffer as the mobile phase. Uric acid obtained by semi-preparative HPLC purification was used as the standard. Data on selectivity, sensitivity and precision demonstrate the reliability of this method.
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    Investigations into the chromatographic behaviour of silica gels produced from ester silicates (1989)
    Springer
    Chromatographia 28 (1989), S. 9-14 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ester silicate silica gels ; Behaviour with organic bases ; Silanol groups ; Acidic centres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Silica gels produced from ester silicates (ES-gels) are excellent chromatographic supports. In comparison with other silica gels the RP-materials obtained from them show little peak tailing even with polar, and, in particular, with basic compounds. Gels produced by various manufacturing processes have been classified by adsorption with methyl pyridinium chloride. ES-gels yield very low methyl pyridinium chloride values and small asymmetry parameters. The results indicate that there are strongly acidic, structurally-related surface centres which cause peak tailing on most commercial gels. It was shown that surface silanols on silica gels do not, in themselves, lead to peak tailing.
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    URL: http://dx.doi.org/10.1007/BF02290374
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    Preparative isolation of (+)-beta-eudesmol fromAmyris balsamifera (1989)
    Springer
    Chromatographia 28 (1989), S. 126-128 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparative isolation ; (+)-Beta-eudesmol ; Amyris balsamifera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Optically pure (+)-beta-eudesmol is a possible starting material for the synthesis of several termite defense compounds. A two step procedure for the isolation of gram quantities of (+)-beta-eudesmol from commercially availableAmyris balsamifera oil (syn. West Indian sandalwood oil), containing 8% beta-eudesmol, was developed. Step one consisted of an efficient vacuum distillation of the total oil. Step two was a medium pressure LC separation with an AgNO3 impregnated silica gel stationary phase. Several other separation procedures failed due to the presence of many closely related sesquiterpene alcohols (75% of the oil).
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    Pressure jumps due to flow interruptions as source of system peaks in liquid chromatography with mixed eluents (1989)
    Springer
    Chromatographia 28 (1989), S. 189-192 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pressure effects ; System peaks ; Sorption equilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Brief pressure changes take often place within a liquid chromatography column, e.g., during sample injection. It is shown that pressure jumps may cause local changes in the composition of a mixed effluent and the rise of system peaks in the chromatogram. This is a consequence of the dependence of sorption equilibrium on pressure.
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    High-performance-liquid chromatographic separation of 1,3,5-trizine herbicides (1989)
    Springer
    Chromatographia 28 (1989), S. 209-211 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Triazine herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A number of 11 triazine herbicides and 7 of their corresponding metabolites were separated in a single HPLC run. The separation was achieved on a reversed-phase column using gradient elution with acetonitrile/buffer. Detection was by UV absorption at a wave-length of 220 nm.
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    Trace enrichment and HPLC analysis of polycyclic aromatic hydrocarbons in environmental samples, using solid phase extraction in connection with UV/VIS diode-array and fluorescence detection (1989)
    Springer
    Chromatographia 28 (1989), S. 203-208 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Polycyclic aromatic hydrocarbons ; Diode array and fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Both the separation of polycyclic aromatic hydrocarbons (PAH's) on tailor made HPLC phases, and their chromatographic enrichment and quantitative determination are of great interest. Because of the generally low concentrations of PAH's in the environment, and the low limiting values in German legislation for drinking water, methods for selective enrichment and sensitive detection are indispensable. On account of their relatively high amounts in soil, the determination of PAH's is valuable for the assessment of the potential danger to ground water by waste materials. These requirements can be fulfilled by used of solid phase extraction on enrichment columns, and fluorescence or UV/VIS diode array detection. For the detection of PAH's in the picogram range, the wavelengths for excitation and emission were time programmed over the chromatogram. With this feature, it is possible to detect all the individual compounds at the highest sensitivity, over the entire analysis.
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    A simple highly reproducible gradient system for micro column HPLC (1989)
    Springer
    Chromatographia 28 (1989), S. 289-292 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micro-bore and capillary columns ; Gradient techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gradient delivery system for microbore and open tubular liquid chromatography is described. A gradient mixing vessel of 5–100μl, or 25–1000μl allows the generation of binary gradients with high reproducibility. The suitability of the system for short packed micro bore columns and open tubular columns is demonstrated.
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    A high-performance liquid chromatographic method for determination of flecainide in human plasma using fluorescence detection (1989)
    Springer
    Chromatographia 28 (1989), S. 303-306 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flecainide in plasma ; Fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high performance liquid chromatographic method for the determination of flecainide in serum has been developed. The analysis is performed on a microparticulate silica column. The eluate is monitored by fluorescence detection at an excitation wavelength of 300nm and an emission wavelength of 370nm. No sources of interference were identified and a coefficient of variation of less than 8% was observed on repeated flecainide determinations. The method has a good reproducibility, specificity and accuracy, and can be applied in therapeutic drug monitoring of flecainide in patients.
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    Synthetic tanning agents. Characterization, control of synthesis and assessment of correlations between product composition and taning properties by reversed-phase high performance liquid chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 391-399 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Synthetic tanning agents ; Correlation of composition and tanning properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gradient elution RP-HPLC has been applied to the separation of the constituents of synthetic tanning agents. Information obtained from the chromatographic results was used to assess the possibility of optimizing the conditions of synthesis, to find out the number of species formed and to make a start at correlating the composition of the tanning agents and their properties.
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    A specific sensitive HPLC method for determination of plasma dopamine (1989)
    Springer
    Chromatographia 28 (1989), S. 307-310 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Plasma Catecholamines ; Dopamine ; Electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We describe here a sensitive, selective and rapid method to quantitate plasma catecholamines, especially dopamine, using high-performance liquid chromatography with electrochemical detection. This method requires a 10-minute run time and has a threshold for detection of 2 picograms, (10pg/ml). A number of commonly employed mobile phases for catecholamine analysis have been tested and have failed to detect dopamine in biological samples. Neither acetonitrile (3–7%) or methanol, (5–8%) in the mobile phase has produced consistently interpretable data either due to inability to detect or interference from co-eluting substances. Optimal detection was achieved with a mobile phase containing sodium acetate (6.8g), citric acid (5.9g), EDTA (48mg), di-n-butylamine (270μl), Na-1-octane sulfate (850mg), methanol (100 ml) (amounts refer to 1 liter aqueous solution) (pH 4.3). The mobile phase was passed through a Waters 5μ resolve C18 column using a Waters 590 pump and m460 electrochemical detector and 740 data module, Flow rate was 0.9ml/min. Using this method, normal values in human and swine left ventricular myocardium and human and swine plasma have been established for norepinephrine, epinephrine, and dopamine.
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    Design of enzyme reactors as chromatographic columns for racemic resolution of amino acid esters (1989)
    Springer
    Chromatographia 28 (1989), S. 193-196 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Immobilized enzymes ; Racemic resolution of amino acid esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Racemic resolution of aromatic and aliphatic amino acid esters into L-amino acid and D-amino acid ester via LC and HPLC is achieved by using enzyme reactors as chromatographic columns. For this purpose α-chymotrypsin and trypsin are immobilized on Eupergit C, Sepharose 4B and Lichrosorb-Diol.
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    Direct preparative resolution of racemic amino-acids using ligand exchange chromatography (chirallec) (1989)
    Springer
    Chromatographia 28 (1989), S. 337-340 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand-exchange ; Preparative racemate resolution ; Amino-acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Preparative resolutions of racemic amino-acids by ligand-exchange chromatography are described. Base-line resolution of multigram quantities of many racemic solutes was obtained using very simple equipment (open tubular column).
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    URL: http://dx.doi.org/10.1007/BF02261011
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    Physico-chemical modelling of solute retention in reversed-phase HPLC with temary mobile phases (1989)
    Springer
    Chromatographia 28 (1989), S. 354-358 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ternary mobile phases ; Solute retention model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In our previous publications we have established a new physico-chemically grounded retention model valid for the adsorption and partition mechanism of retention using multicomponent mobile phases. Moreover, we have demonstrated its practical usefulness for predicting solute retention in several different chromatographic modes (i.e. in TLC, normal-phase and reversed-phase HPLC) employing binary mobile phases. In this paper we give an ultimate check to the physicochemical correctness of our new retention model, using it for the description of solute retention in reversedphase HPLC systems with ternary mobile phases of the B+AB1+AB2 type. The complexity of these mobile phases and of the possible intermolecular interactions among the consitituent solvents was supposed to rigidly scrutinize the premises of the assumed new approach. We have observed a good agreement between the experimental retention parameter for a number of solutes chromatographed with the use of two different mobile phases of the B+AB1+AB2 type, and the retention parameter calculated according to the assumed model. Therefore, we believe to have sufficiently tested our new approach and confirmed its physico-chemical correctness.
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    A highly sensitive method for the determination of adriamycin and adriamycinol in human plasma using HPLC with fluorimetric detection (1989)
    Springer
    Chromatographia 28 (1989), S. 375-378 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fluorimetric detection ; Adriamycin ; Adriamycinol ; Human plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and very sensitive HPLC method, for the simultaneous determination in human plasma of adriamycin and its metabolite adriamycinol, is described. Plasmas from patients were stored frozen. Thawed samples were extracted by absorption of anthracyclin onto a small C18 column. After evaporation of the eluate and reconstitution of the residue with methanol (100μL), 30 to 40μL of the mixture were injected into the chromatograph. Separation was obtained using an RP 8 column with a mobile phase of formate buffermethanol-acetonitrile (50∶23∶27, v/v). A spectrofluorimeter was used as detector. The limit of sensitivity of the assay was 50 pcg/ml of plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261018
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  • 98
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    A simple method for concentrating volatile flavor compounds in aqueous systems using RP-HPLC (1989)
    Springer
    Chromatographia 28 (1989), S. 405-411 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Concentration of volatile flavor compounds ; ODS packing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Volatile flavor compounds in aqueous model systems, distillates of coffee extract and juices such as apple, tomato, pineapple and grape were adsorbed on an ODS column during HPLC and monitoring absorption at 280nm. The adsorbed volatile compounds were eluted with a small volume of ethanol. Volatile compounds in the eluates were concentrated 22 to 100 times those in the distillates. Recovery of compounds was 50–90%. Breakthrough of specific compounds such as γ-valerolactone, furfuryl acetate and t-2-hexenal in the model systems and several compounds in the juice distillates was detected by capillary GC. Pattern similarity calculated between the GC profiles of a juice distillate and the corresponding eluate gave a qualitative comparison. This novel and versatile method utilizing conventional RP-HPLC may be widely applicable for concentrating volatiles in aqueous systems, at levels from ppm to ppb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261023
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  • 99
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    Electronic Resource
    HPLC determination of the phenolic metabolites of phenoxy alkanoic acid herbicides (1989)
    Springer
    Chromatographia 28 (1989), S. 465-468 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chlorinated phenols ; 4-Aminoantipyrine derivatives of phenols ; Metabolites of phenoxy alkanoic acid herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High performance liquid chromatography (HPLC) has been applied to the separation and determination of o-chlorophenol, 2,4-dichlorophenol, 3,4-dichlorophenol, 2,5-dichlorophenol, and 2,4,5-trichlorophenol in water samples after prior derivatization with 4-aminoantipyrine. These substances are the phenolic decomposition products of the phenoxy-alkanoic acid herbicides: 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4-dichlorophenoxybutyric acid (2,4-DB), and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). An RP-C18 column was used, with gradient elution starting at 50/50 and changing to 70/30 methanol/water (v/v) after 24 min. Detection was carried out at 470 nm where the 4-aminoantipyrilquinonimine derivatives show maximum absorbance. The method was linear over a concentration range of 5–10,000 ppb phenol in the original water sample. By using an enrichment step a detection limit of 2 ppb phenol could be approached. The method was used to study the degree of degradation of the phenoxy acids to phenols under different conditions of temperature, pH, and UV irradiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261061
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  • 100
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    Electronic Resource
    Determination of the micelle-solute association constants of some benzene and naphthalene derivatives by micellar high performance liquid chromatograph (1989)
    Springer
    Chromatographia 28 (1989), S. 379-384 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micelle-solute association constants ; Benzene and naphthalene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The interaction of some benzene and naphthalene derivatives with sodium dodecyl sulphate, hexadecyltrimethylmmonium bromide and polyoxyethylene [23] dodecanol micelles has been evaluated by high operformance liquid chromatography using micellar mobile phases. The micelle-solute association constants have been obtained for the compounds investigated. Good correlation between free energy of transfer for water-micelles and for octanol-water has been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261019
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