Journal of chromatography最新文献

{"title":"Application of solid-phase microextraction to the headspace gas chromatographic analysis of halogenated volatiles in selected foods.","authors":"B D Page,&nbsp;G Lacroix","doi":"10.1016/0021-9673(93)83303-a","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83303-a","url":null,"abstract":"<p><p>Solid-phase microextraction (SPME), with the poly(dimethylsiloxane)-coated silica fiber suspended and equilibrated in the headspace, has been applied to the capillary gas chromatographic (GC) analysis of 33 halogenated volatile contaminants in model aqueous solutions and in foods. With electrolytic conductivity detection, the limits of detection in water ranged from 1.5 micrograms/kg for vinyl chloride to < or = 0.005 microgram/kg for the tri- to hexachlorobenzenes. Headspace SPME-GC shows a much greater response for the less volatile analytes than those of greater volatility, a procedure complementing headspace GC with gas sampling. In model systems or foods, increasing lipid material decreased the headspace extraction. With 50 mg of lipid, the headspace extraction decreased about 50% for analytes with LODs about 0.1 microgram/kg and by > or = 99.5% for the above chlorobenzenes. Standard addition was used to analyze a variety of beverages and dry foods and to determine the analyte partitions.</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"648 1","pages":"199-211"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83303-a","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19233751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-performance liquid chromatography of the photoproducts of nucleic acid components. III. Detection of the secondary structure differences in sequence isomeric self-complementary oligonucleotides.","authors":"V N Potaman,&nbsp;I P Chernov,&nbsp;V V Demidov","doi":"10.1016/0021-9673(93)83296-5","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83296-5","url":null,"abstract":"<p><p>Reversed-phase high-performance liquid chromatography (RP-HPLC) was used to detect differences in the secondary structures of two self-complementary oligodeoxyribonucleotides. The [d(CCTTTAAAGG)]2 duplex assumes an ordinary B-conformation in aqueous solution, while [d(GGAAATTTCC)]2 is known to contain in its central part a stretch of a more rigid B'-form conformation with significantly lowered fluctuational mobility of base pairs. The latter factor causes a marked difference in the amounts of thymine cyclobutane photodimers formed under UV irradiation of corresponding duplexes as revealed by chromatography of two single-stranded oligonucleotides. Increasing the temperature below the duplex melting temperature (stimulation of the B'-B structural transition) results in an increase in photodimer formation that was inhibited in the B'-form. Thus, we demonstrate the usefulness of RP-HPLC for duplex DNA structural studies.</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"648 1","pages":"151-6"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83296-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19233750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of high-performance liquid chromatography and capillary electrophoresis in the analysis of somatostatin analogue peptides.","authors":"M Idei,&nbsp;I Mezö,&nbsp;Z Vadász,&nbsp;A Horváth,&nbsp;I Teplán,&nbsp;G Kéri","doi":"10.1016/0021-9673(93)83308-f","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83308-f","url":null,"abstract":"<p><p>HPLC and CE methods were developed for analysis of somatostatin analogue (S-analogue) peptides utilizing triethylammonium phosphate-organic solvent modifier solvents as the CE buffer and HPLC eluent. Acetonitrile, methanol, ethanol and 2-propanol were applied as organic modifiers. The applicability of HPLC and CE systems was evaluated and compared. Optimum conditions for the separation were determined for both methods. Retention (migration) time, elution order and selectivity can be influenced by modifying the composition of the eluent (buffer) with organic solvents not only in HPLC but also in CE. Although the HPLC system reacted to changes in the organic solvent concentration in a much more sensitive way than the CE system did (from the point of view of retention time), CE proved to be a more suitable method for separating the peptides investigated. Baseline separation could be achieved within 6-9 min by CE, a result which was impossible to achieve with HPLC working in the isocratic mode. In CE the effect of the alcohols on migration times proved to be opposite to that of acetonitrile. Whereas ACN decreased, the alcohols increased the migration times in a concentration-dependent way. The results suggest that CE can be applied very advantageously in peptide analysis. Its performance regarding selectivity, resolution, theoretical plate number, duration and cost is comparable or sometimes superior to that of HPLC.</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"648 1","pages":"251-6"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83308-f","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18899114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Separation of neuropeptide Y diastereomers by high-performance liquid chromatography and capillary zone electrophoresis.","authors":"D A Kirby,&nbsp;C L Miller,&nbsp;J E Rivier","doi":"10.1016/0021-9673(93)83309-g","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83309-g","url":null,"abstract":"<p><p>Separation of analogues of neuropeptide Y (NPY) in which a single D-amino acid replaced the corresponding naturally occurring residue was performed by chromatographic techniques to ensure the quality of the synthetic peptides to be used for structural and biological studies. Of the 35 compounds, 28 were easily separated (alpha = 1.02-2.76) from native NPY by standard reversed-phase high-performance chromatography (RP-HPLC) methods using a Vydac C18 column and a gradient buffer system developed in our laboratory comprised of triethylammonium phosphate (TEAP) at pH 2.25 and acetonitrile at 40 degrees C. The identical diastereomers could be separated on the same solid support and by using 0.1% trifluoroacetic acid (TFA) as the mobile phase modifier, however separation factors were smaller and retention times were longer. Three of the remaining seven unresolved analogues were separated (alpha = 1.02-1.96) by changing the solid-phase support to Vydac diphenyl derivatized silica and a buffer system consisting of 0.1% TFA and acetonitrile. Of the four remaining unresolved analogues, only two could be separated by capillary zone electrophoresis (CZE) in 0.1 M sodium phosphate at pH 2.5, but all four were finally resolved by changing the electrophoretic buffer to 0.1 M TEAP buffer at pH 2.5. Migration times of the diastereomers differed by 0.2-2.0 min from that of the natural NPY. In addition to confirming the uniqueness of each isomer, this investigation demonstrated the expansive utility and high efficiency of the TEAP buffer system for both RP-HPLC and CZE as well as the difference in selectivity produced by the TEAP and TFA buffers in RP-HPLC.(ABSTRACT TRUNCATED AT 250 WORDS)</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"648 1","pages":"257-65"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83309-g","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19234382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid method for the fractionation of nuclear proteins and their complexes by batch elution from hydroxyapatite.","authors":"A Zagariya,&nbsp;S Khrapunov,&nbsp;W Zacharias","doi":"10.1016/0021-9673(93)83311-f","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83311-f","url":null,"abstract":"<p><p>A new procedure for the separation and purification of nuclear proteins and their complexes by batch elution from hydroxyapatite is presented. This method allows to isolate such proteins with different basic character faster and more efficiently than procedures using column chromatography, while showing high selectivity, sensitivity, simplicity, mild conditions of purification, reproducibility and protein stability.</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"648 1","pages":"275-8"},"PeriodicalIF":0.0,"publicationDate":"1993-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83311-f","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22252286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid analysis of enzymatic digests of a bacterial protease of the subtilisin type and a \"bio-engineered\" variant by high-performance liquid chromatography-frit fast atom bombardment mass spectrometry.","authors":"W D van Dongen,&nbsp;C Versluis,&nbsp;P D van Wassenaar,&nbsp;C G de Koster,&nbsp;W Heerma,&nbsp;J Haverkamp","doi":"10.1016/0021-9673(93)83410-t","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83410-t","url":null,"abstract":"<p><p>Amino acid sequencing of a subtilisin-type bacterial protease and a bio-engineered variant was carried out by investigating various enzymatic digests using HPLC-frit fast atom bombardment MS methods. The fast atom bombardment mass spectral data allowed rapid identification of the enzymatically generated peptides and differentiation between both proteins. The feasibility of determining the positions and nature of mutations in the amino acid sequence depends mainly on the size of the peptides containing the modifications.</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"647 2","pages":"301-9"},"PeriodicalIF":0.0,"publicationDate":"1993-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83410-t","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19216224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of the chemical structure of sulphated glycosaminoglycans after enzymatic digestion. Application of liquid chromatography-mass spectrometry with an atmospheric pressure interface.","authors":"R Da Col,&nbsp;L Silvestro,&nbsp;A Naggi,&nbsp;G Torri,&nbsp;C Baiocchi,&nbsp;D Moltrasio,&nbsp;A Cedro,&nbsp;I Viano","doi":"10.1016/0021-9673(93)83409-l","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83409-l","url":null,"abstract":"<p><p>Pneumatically assisted electrospray was demonstrated to be a powerful ionization source for the analysis of oligosaccharides. A mass spectrometer was interfaced to an HPLC system, using this interface, to determine oligosaccharides from the enzymatic digestion of heparin separated on a reversed-phase column. To set up the technique, and particularly to clarify the ionization process, purified disaccharides, from enzymatic digestion of chondroitin sulphates, were measured. The use of a suitable counter ion in the mobile phase, tetrapropylammonium (TPA), to optimize the HPLC separation, gave, with sulphated di- and oligosaccharides, adducts [M + nTPA - (n + m)H]m-, which were unexpectedly stable to fragmentation; molecular ions [M - (n + 1)H]n-, in the presence of the counter ion, were observed only with desulphated or monosulphated disaccharides. The stability of the adducts and the use of a deuterated ion-pair reagent permitted an exact evaluation of the molecular masses of disaccharides and oligosaccharides of unknown structure. Spectra obtained in the absence of the counter ion contained singly or multiply charged molecular ions and fragmentation ions mainly from loss of the sulphate groups; under these ionization conditions the exact mass determination and interpretation of the spectra were difficult. After removal of the counter ion, tandem mass spectra could be obtained with some interesting data for the characterization of these molecules. Complete spectral analyses were performed with amounts of samples of 50 micrograms but, using microbore columns, one twentieth of this amount may give good spectra.</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"647 2","pages":"289-300"},"PeriodicalIF":0.0,"publicationDate":"1993-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83409-l","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19216223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pseudo-electrochromatography--negative-ion electrospray mass spectrometry of aromatic glucuronides and food colours.","authors":"M Hugener,&nbsp;A P Tinke,&nbsp;W M Niessen,&nbsp;U R Tjaden,&nbsp;J van der Greef","doi":"10.1016/0021-9673(93)83418-r","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83418-r","url":null,"abstract":"<p><p>Pseudo-electrochromatography is a combination of liquid chromatography and an electromigration technique, especially directed at the separation of ionic compounds prior to mass spectrometric detection with a mobile phase composition compatible with mass spectrometry. The application of pseudo-electrochromatography to the separation of food colours and aromatic glucuronides is described. An example of selectivity tuning by applying voltages of differing polarity during the chromatographic run is given. The coupling of pseudo-electrochromatography with electrospray mass spectrometry is demonstrated. Differences in the effects of the axial potential over the column between silica-based and polymeric packing materials are discussed.</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"647 2","pages":"375-85"},"PeriodicalIF":0.0,"publicationDate":"1993-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83418-r","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19216225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a high-performance liquid chromatographic-mass spectrometric technique, with an ionspray interface, for the determination of platelet-activating factor (PAF) and lyso-PAF in biological samples.","authors":"L Silvestro,&nbsp;R Da Col,&nbsp;E Scappaticci,&nbsp;D Libertucci,&nbsp;L Biancone,&nbsp;G Camussi","doi":"10.1016/0021-9673(93)83406-i","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83406-i","url":null,"abstract":"<p><p>An HPLC-mass spectrometric technique with an ionspray interface was developed for the determination of platelet-activating factor (PAF) and PAF-related compounds in biological samples. HPLC separations were performed using a reversed-phase column. The mass spectra showed intense [M + H]+ ions. Collision-induced dissociation of protonated molecular ions gave characteristic daughter ions corresponding to the phosphorylcholine group. By selective-ion monitoring, a detection limit of 0.3 ng was obtained for all molecules; by multiple reaction monitoring, the same sensitivity was achieved for PAF whereas for lyso-PAF the limit was 3 ng. Finally, PAF was comparatively determined by bioassay and HPLC-MS after extraction from the cell pellets and the supernatants of human polymorphonuclear neutrophils unstimulated or stimulated with opsonized zymosan. The good correlation observed between these techniques indicated the reliability of HPLC-MS for biochemical studies on PAF and PAF-related molecules.</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"647 2","pages":"261-9"},"PeriodicalIF":0.0,"publicationDate":"1993-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83406-i","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19216222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of penicillin G, ampicillin, amoxicillin, cloxacillin and cephapirin by high-performance liquid chromatography-electrospray mass spectrometry.","authors":"R F Straub,&nbsp;R D Voyksner","doi":"10.1016/0021-9673(93)83336-q","DOIUrl":"https://doi.org/10.1016/0021-9673(93)83336-q","url":null,"abstract":"<p><p>This report contributes to a preliminary investigation of high-performance liquid chromatographic (HPLC)-mass spectrometric (MS) methods for confirming beta-lactam antibiotic residues in bovine milk. Initial work for each antibiotic evaluated the collisional activated dissociation (CAD) spectra that could be generated between the capillary and skimmer in the electrospray (ESP) interface. The drugs show various characteristic fragmentation, mostly within the beta-lactam ring and the amide group. Response for a particular compound in a given solvent can vary drastically. Usually, the more organic component in the solvent, the higher the ESP response. In many cases use of acetonitrile also results in slightly better ion currents than for methanol when comparing equal percentages of either organic solvent in water. The ESP response of most of the tested antibiotics can be enhanced by the addition of formic acid or acetic acid to the mobile phase methanol-water (1:1). In general, the negative ion spectra are lower in intensity, exhibiting an [M-H]- ion and producing less fragmentation at higher CAD voltages as compared to positive ion spectra. An isocratic reversed-phase HPLC method for the separation of a mixture of five common beta-lactam antibiotics was developed using acetic acid as a mobile phase additive and optimized for detection with a new ESP HPLC-MS interface. A post-column split ratio of 70:1 for the eluent from a 150 x 2 mm I.D. column was chosen to provide the required lower flow-rate (approximately 4 microliters/min). The limit of detection for the simultaneous determination of these antibiotics was estimated to be 100 ppb. Electrospray HPLC-MS could be used to confirm these antibiotics for quantities down to about 100 pg entering the mass spectrometer. Multiresidue analysis with microbore HPLC-ESP-MS has the advantage that no post-column splitting of the eluent is required and all of the analyte (on-column injected) will be transferred into the ESP interface. Preliminary work showed good mass spectrometric sensitivity down to the level of regulatory interest, but chromatographic separation efficiency must be improved.</p>","PeriodicalId":15508,"journal":{"name":"Journal of chromatography","volume":"647 1","pages":"167-81"},"PeriodicalIF":0.0,"publicationDate":"1993-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9673(93)83336-q","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19393249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}