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PubMed1987

New solvent system for high-performance thin-layer chromatography and high-performance liquid chromatography of gangliosides.

New solvent systems consisting of acetonitrile, isopropanol and aqueous 50 mM potassium chloride or 2.5 M ammonium hydroxide were developed for the separation of gangliosides by high-performance thin-layer chromatography. These solvent systems seem to be superior for the resolution of polysialogangliosides such as tetra-, penta- and hexasialo species, as compared to chloroform-methanol-aqueous salt systems. The order of mobility of gangliosides in the ammoniacal solvent system is GD3 greater than GD1a greater than GM1 greater than GT1b greater than GD1b as compared with GM1 greater than GD3, GD1a greater than GD1b greater than GT1b in the neutral septem. A combination of these two solvent systems provides excellent two-dimensional separations of complex ganglioside mixtures. The neutral solvent system, acetonitrile-isopropanol-aqueous 50 mM potassium chloride, can be used for the separation of underivatized gangliosides by high-performance liquid chromatography on an Aquasil SS silica gel column. Ganglioside elution can be monitored at 208 nm because of the good UV-transparency of the effluent.

Chromatography, High Pressure Liquid↗
PubMed1989

High-performance liquid chromatography and capillary supercritical-fluid chromatography separation of vegetable carotenoids and carotenoid isomers.

Carotenoids from carrots and tomatoes were separated with high-performance liquid chromatography (HPLC) and capillary supercritical fluid chromatography (SFC). All trans alpha- and beta-carotene were separated from their respective cis-isomers with capillary SFC. Carotenoids extracted from tomatoes included xanthophyll, lycopene and beta-carotene, while alpha- and beta-carotene were extracted from carrots. The HPLC separations were accomplished isocratically with a 25-cm column containing 5-microns ODS and methanol-acetonitrile-chloroform (47:47:6) or acetonitrile-dichloromethane (80:20). beta-Carotene cis-isomers were separated with SFC with a SB-cyanopropyl-25-polymethylsiloxane column, while alpha-carotene isomers were separated with two SB-cyanopropyl-50-polymethylsiloxane columns. Carotenoids from carrots and tomatoes were separated with a SB-phenyl-50-polymethylsiloxane column. Carbon dioxide with 1% ethanol was the SFC mobile phase. The eluent was monitored at 461 nm for HPLC and either 453 or 461 nm for SFC.

Carotenoids↗
PubMed1990

Comparison of high-performance liquid chromatography, supercritical fluid chromatography and capillary zone electrophoresis in drug analysis.

High-performance liquid chromatography (HPLC), supercritical fluid chromatography (SFC) and capillary zone electrophoresis (CZE) are compared with respect to their usefulness in drug analysis. Factors discussed include efficiency, performance, sensitivity, optimization parameters, method development time, sample preparation, technical difficulties, orthogonality of the information obtained and the possible application to various substance groups. It is concluded that HPLC can be applied successfully in virtually all areas of pharmaceutical analysis. CZE has a promising future in the analysis of drugs and in the field of biotechnological analysis, where a high number of plates is required together with a short analysis time. Nevertheless improvements in detection are still necessary for most applications. SFC is particularly suitable for moderately polar compounds or substances for which mass-sensitive detection is required. SFC and CZE can be considered as complementary to HPLC owing to the orthogonality of the acquired data, and as a result more information can be obtained from the analysis.

Chromatography, High Pressure Liquid↗
PubMed1991

Clean-up of plasma extracts by gel permeation chromatography during analysis of isosorbide nitrates by capillary gas chromatography.

This work describes how gel permeation chromatography (GPC) can be used for sample clean-up to reduce the fouling of the column in an automated on-column injector. The analytes were isolated from plasma together with the internal standard (isomannide dinitrate) by liquid-liquid extraction on Extrelut silica columns. The extracts were evaporated and reconstituted in tetrahydrofuran for separation of the analytes from non-volatile plasma components by GPC on a styrene-divinylbenzene column with 100 A pore size. A programmable autosampler with an additional three-way valve was used for injection and fraction collection. The molecular weight fraction between 100 and 700 a.m.u. was collected and transferred to the on-column autosampler for capillary gas chromatography on a 30-m column butt-connected to a 0.2-m pre-column. The pre-column was replaced after 50 sample injections. When the GPC purification was excluded from the work-up procedure a deposit of non-volatile components was formed at the injection zone of the pre-column which resulted in excessive peak-tailing after only five or six injections of plasma extract. The limit of determination was 0.2 ng/ml plasma for isosorbide dinitrate and 0.4 ng/ml for the mononitrates.

Blood↗
PubMed1991

Analysis of sulphonamides using supercritical fluid chromatography and supercritical fluid chromatography-mass spectrometry.

Packed-column supercritical fluid chromatography has been used for the separation of mixtures of sulphonamides on silica and amino-bonded stationary phases utilizing carbon dioxide with methanol modifier as the mobile phase. The effect of modifier concentration, column pressure and modifier identity on retention was also studied. Packed-column supercritical fluid chromatography-mass spectrometry (SFC-MS) of these mixtures utilizing both moving-belt and modified thermospray interfaces was also studied. The identification of sulphamethazine in a spiked porcine kidney extract was performed by SFC-MS using the moving-belt interface.

Animals↗
PubMed1989

Coupled high-performance liquid chromatography-gas chromatography for the determination of pesticide residues in biological matrices.

A fully automated high-performance liquid chromatography-gas chromatography (HPLC-GC) network is described. A ten-port valve set up as a loop type LC-GC interface allowed the transfer of large LC effluent fractions into the gas chromatograph by concurrent solvent evaporation. The system performed highly efficient sample enrichment and clean up by LC and on-line GC separation with sensitive electron-capture detection. The efficiency of the system was demonstrated by application to the trace analysis of N-(3-chloro-2,6-dimethylphenyl)-N-(2-oxotetrahydrofuranyl)-2-me thoxyacetamide (CGA 80000) in various crops and soil samples. The residue level determined was 0.02 mg/kg for crop samples and 0.01 mg/kg for soil samples. The relative standard deviations of the calibration graphs were in the range 2-5%; the mean recovery was greater than 85%.

Acetamides↗
PubMed1990

High-performance liquid chromatography of amino acids, peptides and proteins. XCVII. The influence of the gradient elution mode and displacer salt type on the retention properties of closely related protein variants separated by high-performance anion-exchange chromatography.

The influence of different elution modes, gradient times and flow-rates on the relative retention of closely related variants of carbonic anhydrase and ovalbumin has been investigated using high-performance ion-exchange chromatography. Three isoform species of carbonic anhydrase and four isoforms related to ovalbumin eluted by anion-exchange chromatography were characterised by isoelectric focusing and sodium dodecylsulphate-polyacrylamide electrophoresis. Gradient retention data were collected using several different alkali metal halides as the displacer salt, in order to systematically evaluate the effect on selectivity of different anions and cations in the series F-, Cl- and Br-, and Li+, Na+ and K+. While the selectivity between the different ovalbumin isoform species remained essentially constant with each displacer salt, solute Zc-values [J. Chromatogr., 458 (1988) 27] varied with the type of salt. In contrast, non-parallel retention plots were obtained for the carbonic anhydrase isoforms with the Zc values different for each isoform. Furthermore, significant differences in chromatographic behaviour for these proteins were observed between experiments carried out under gradient elution conditions with either varied gradient time and constant flow-rates or fixed gradient time and varied flow-rates. These results are discussed in terms of the influence of column residence time and protein-salt interactions of the solute's interactive ionotope and the concomitant effects these structural perturbations may have on chromatographic behaviour.

Amino Acids↗
PubMed1990

Preparative separation of sphingolipids and of individual molecular species by high-performance liquid chromatography and their identification by gas chromatography-mass spectrometry.

Six fractions containing tri- to pentaglycosylceramides were isolated from the green, fresh water alga Chlorella kessleri, grown heterotrophically, by using preparative high-performance liquid chromatography (HPLC). Up to twelve fractions were obtained by further reversed-phase HPLC of each glycosylceramide. The use of a polar capillary column with Supelcowax 10 as the stationary phase allowed an excellent separation of the individual molecular species of ceramides, even though the separation did not occur when the ceramides differed only in the position of the amide bond. The individual molecular species (even if present in mixtures) were identified by gas chromatography-chemical ionization mass spectrometry. The evidence for a complete structure was obtained by enzyme splitting with alpha- and beta-galactosidases (the sequence of monosaccharides) and by negative ionization fast atom bombardment mass spectrometry. More than 400 molecular species of glycosylceramides were identified.

Ceramides↗
PubMed1988

Synthesis and purification of deoxyribose analogues of NAD+ by affinity chromatography and strong-anion-exchange high-performance liquid chromatography.

Two different chemical analogues of NAD+, containing either 2'-deoxyribose (2'-dNAD+) or 3'-deoxyribose (3'-dNAD+) were synthesized enzymatically with oxidized nicotinamide mononucleotide (NMN+)-adenyl transferase (E.C. 2.7.7.18). These compounds were efficiently purified by affinity chromatography on a boronate gel, followed by strong-anion-exchange high-performance liquid chromatography under isocratic conditions. These chromatographic steps resulted in the elimination of unreacted deoxyadenosine triphosphates (dATP) and NMN+, respectively. The purified dNAD+ isomers were examined as possible substrates of homogeneous poly(ADP-ribose) polymerase, purified from calf thymus. 3'-dNAD+ was effectively utilized as a substrate by the polymerase, which catalyzed the formation of protein-bound poly(3'-dADP-ribose) during automodification. However, 2'-dNAD+ was not a substrate for the automodification reaction catalyzed by this DNA-dependent enzyme. Instead, 2'-dNAD+ was a potent non-competitive inhibitor of NAD+ in the elongation reaction.

Chromatography, Affinity↗
PubMed1987

Chiral separation of enantiomers of substituted alpha- and beta-alanine and gamma-aminobutyric acid analogues by gas chromatography and high-performance liquid chromatography.

Gas chromatography (GC) with a chiral stationary phase, Chirasil-Val, has been used for separation of the enantiomers of several analogues of alpha- and beta-alanine as their N-trifluoroacetyl isopropyl esters. The same chiral phase GC procedure has been applied to the enantiomeric separation of various substituted gamma-aminobutyric acid analogues (GABA). Reversed-phase high-performance liquid chromatography (HPLC) with the chiral copper-L-proline complex allowed a clear resolution of all the alpha-amino acids in their underivatized forms. It yielded somewhat smaller separation coefficients for the substituted beta-alanines and no resolution for the GABA analogues. The influence of the nature of the amino acid, alpha, beta or gamma, and the effects of the different substituents on the separation coefficients obtained by GC and HPLC are discussed.

Alanine↗
PubMed1991

Determination of bovine butterfat triacylglycerols by reversed-phase liquid chromatography and gas chromatography.

Triacylglycerols (TGs) from a sample of summer butterfat (bovine milk) were analysed and fractionated by reversed-phase liquid chromatography (RPLC). Fatty acid and TG composition of eac of the 47 RPLC fractions ranging from 0.1 to 6.9% were determined by capillary gas chromatography. The data were used together to determine the quantitative composition of the molecular species of TGs. A large number of TG species, accounting for 80% of the total, could be unequivocally identified and individually determined. The combination of the chromatographic methods used proved to be a powerful and accurate approach for the determination of molecular species of TGs in a complex fat, but also a difficult and time-consuming task.

Animals↗
PubMed2002

Utilisation of reversed-phase high-performance liquid chromatography as an alternative to silver-ion chromatography for the separation of cis- and trans-C18:1 fatty acid isomers.

Silver ion-high-performance liquid chromatography (HPLC) has been commonly used for the separation and the analysis of trans-18:1 isomers in partially hydrogenated oils and milk fat. This paper describes an easy HPLC method using two reversed-phase columns. The cis- and trans-18:1 fatty acids isomers as methyl esters were eluted as two separate fractions. The collected fractions were analysed by gas chromatography (GC). The purity of the two fractions were tested by GC-MS and GC-Fourier transform IR.

Chromatography, Gas↗
PubMed2002

Determination of toxic compounds in paper-recycling process waters by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry.

Three analytical methods were developed for the determination of toxic compounds in recirculating waters of a paper-recycling industry. Three main groups of compounds were considered: (i) wood extractives originated from the raw material; (ii) biocides added during the production process and (iii) surfactants and other adjuvants present in the formulates of these biocides. Wood extractives considered in this study included fatty and resin acids. They were analysed by liquid-liquid extraction using methyl tert.-butyl ether, followed by gas chromatography-mass spectrometry for previous formation of the respective trimethylsilyl esters. Water samples were also extracted with Oasis HLB (copolymer [poly(divinylbenzene-co-N-vinylpyrrolidone]) solid-phase extraction cartridges of 60 mg and analysed by liquid chromatography-electrospray mass spectrometry for the determination of additives and biocides. Using these two approaches levels up to 15 mg/l for total resin and fatty acids, 5 mg/l for alkylbenzene sulfonates and 2-(thiocyanomethylthio)benzotiazol, 100 microg/l for bisphenol A and 2,2-dibromo-3-nitrilepropionamide, and 300 microg/l for nonylphenol ethoxycarboxylate were detected in process waters at different production treatment stages. These levels are of relevance since poor water quality affects the paper-recycling process, the primary water treatment process and eventually, the environmental water quality.

Chromatography, Liquid↗
PubMed2003

Coupled liquid chromatography-gas chromatography for the rapid analysis of gamma-oryzanol in rice lipids.

An approach based on on-line coupled liquid chromatography-gas chromatography (LC-GC) was developed for the rapid analysis of gamma-oryzanol in rice. Total lipids were extracted from rice and subjected to LC-GC without any prior purification. gamma-Oryzanol was pre-separated by HPLC from rice lipids and transferred on-line to GC analysis in order to separate its major constituents. 24-methylenecycloartanyl ferulate, cycloartenyl ferulate, campesteryl ferulate, beta-sitosteryl ferulate and campestanyl ferulate. The identities of the compounds were confirmed by off-line GC-MS analysis. Total gamma-oryzanol content could be quantified by HPLC-UV detection and the distribution of gamma-oryzanol constituents could be determined by on-line coupled GC analysis. The proposed methodology paves the way for high-throughput investigations providing information on natural variations in gamma-oryzanol content and its composition in different rice varieties.

Chromatography, Gas↗
PubMed2002

Structural analysis of a glycoprotein by liquid chromatography-mass spectrometry and liquid chromatography with tandem mass spectrometry. Application to recombinant human thrombomodulin.

Using recombinant human thrombomodulin (rhTM) expressed in Chinese hamster ovary (CHO) cells, we studied the structural analysis of a glycoprotein by liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography with tandem mass spectrometry (LC-MS-MS). First, we analyzed the structure of both the O- and N-linked glycans in rhTM by oligosaccharide mapping using LC-MS equipped with a graphitized carbon column (GCC-LC-MS). Major O- and N-linked glycans were determined to be core 1 structure and fucosyl biantennary containing NeuAc(0-2) respectively. Next, the post-translational modifications and their heterogeneities, including the site-specific glycosylation, were analyzed by mass spectrometric peptide/glycopeptide mapping of trypsin-digested rhTM and precursor-ion scanning. Precursor-ion scanning was successful in the detection of five glycopeptides. Four N-glycosylation sites and their site-specific carbohydrate heterogeneity were determined by their mass spectra. O-Glycosylation could be estimated on the basis of its mass spectrum. We were able to identify partial beta-hydroxylation on Asn324 and Asn439, and O-linked glucose on Ser287 from the peptide/glycopeptide map and their mass spectra. We demonstrated that a sequential analysis of LC-MS and LC-MS-MS are very useful for the structural analysis of O- and N-linked glycans, polypeptides, and post-translational modifications and their heterogeneities, including site-specific glycosylation in a glycoprotein. Our method can be applied to a glycoprotein in biological samples.

Amino Acid Sequence↗
PubMed2003

On-line coupled liquid chromatography-gas chromatography.

On-line coupled liquid chromatography-gas chromatography (LC-GC) is a powerful technique that combines the best features of LC and GC and is ideal for the analysis of complex samples. This review describes the unique features of on-line coupled LC-GC. The different interfaces and evaporation techniques are presented, along with their advantages and disadvantages. Guidelines are given for selecting a suitable LC-GC technique and representative applications are noted.

Chromatography, Gas↗
PubMed2003

Comparison of gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry for the determination of fatty and resin acids in paper mill process waters.

A comparative study of the performance of liquid chromatography (LC)-atmospheric pressure chemical ionisation (APCI)-mass spectrometry (MS) and gas chromatography (GC)-mass spectrometry techniques for the determination of resin and fatty acids from paper mill process waters was carried out. These compounds are responsible for the high toxicity of paper mill effluents and little research has been carried out regarding their analysis using mass spectrometric techniques. To prove the usability of GC and LC-MS, 16 treated and untreated water samples of recycle, kraft and pulp paper mills were analysed and good agreement was observed as regards to compounds detected and corresponding concentrations. This paper also reports the limits of detection, recoveries, reproducibility, linearity and precision using the two methods. GC-MS presented better selectivity and lower detection limits (below 0.2 microg/l), but derivatization of the extracts and the short life of derivatives (12-24 h) made the technique tedious and prone to high variations. Although LC-APCI-MS presented coelution of the non-aromatic resin acids, it also showed good sensitivity (limits of detection <3 microg/l) and permitted the detection of resin and fatty acids at microg/l level. In addition, since samples could be directly injected to the chromatographic system, LC-APCI-MS was proven as a powerful technique for quick and unequivocal quality control during papermaking.

Atmospheric Pressure↗