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At least 19 recordsLinked to original sources
PubMed1979

Disopyramide determination by gas chromatography, liquid chromatography, and gas chromatography--mass spectrometry.

Disopyramide is determined in serum by gas chromatography with a nitrogen-selective detector, by liquid chromatography, and by gas chromatography--mass spectrometry. Comparable results are obtained with the three techniques, with a within-run and between-run precision of 5 to 10% (coefficient of variation). Least-squares analysis of data on patients' sera, analyzed first by gas chromatography (y) and then liquid chromatography (x), gave a slope of 1.12; y-intercept, -0.31; standard error of estimate, 0.46; and correlation coefficient, 0.94. Comparison of patients' sera by gas chromatography (y) and then by gas chromatography--mass spectrometry (x) gave a slope of 0.94; y-intercept, 0.42; standard error of estimate, 0.38; and correlation coefficient, 0.97. Interferences observed when using one technique--for example, gas chromatography--can be eliminated by analyzing the sample extract with one of the other techniques.

Chromatography, Gas↗
PubMed1992

Determination of organophosphorus pesticides in fruits by on-line size-exclusion chromatography-liquid chromatography-gas chromatography-flame photometric detection.

The determination of organophosphorus pesticides in fruits by size-exclusion chromatography (SEC) on a polystyrene column coupled on-line to a gas chromatography (GC) system was unsatisfactory as a result of interfering peaks in GC. A liquid chromatography step on silica gel was therefore inserted between the SEC and GC steps to filter out polar by-products. Samples of fruit (apples, grapes and kiwi fruits) were extracted, then the extract filtered or centrifuged and injected into an automated on-line SEC-liquid chromatography-GC-flame photometric detection. Recoveries were about 95% and the detection limits about 1 ng/g.

Chromatography, Gas↗
PubMed1990

Identification of triacylglycerols by high-performance liquid chromatography-gas-liquid chromatography and liquid chromatography-mass spectrometry.

Triacylglycerols from rat adipose tissue were chromatographed by high-performance liquid chromatography (HPLC), with a gradient of propan-2-ol in acetonitrile as the mobile phase. Fractions of the material eluting from the column were collected and analysed by automated gas - liquid chromatography of the fatty acid methyl esters obtained after transmethylation. Triacylglycerols were identified by using a combination of their fatty acid content and elution time from the HPLC column. Fractions corresponding to whole peaks or groups of peaks were also collected and re-chromatographed on a liquid chromatography - mass spectrometry system equipped with a belt interface. For most triacylglycerols, good agreement was obtained between the two methods, although mass spectrometric identification of the early eluting peaks was complicated by poor resolution of the triacylglycerols on the HPLC system.

Adipose Tissue↗
PubMed1991

Liquid chromatographic analysis of a potential polymeric-pendant drug delivery system for peptides. Application of high-performance size-exclusion chromatography, reversed-phase high-performance liquid chromatography and ion chromatography to the evaluation of biodegradable poly[(chloromethoxytrialanine methyl ester)phosphazenes].

A novel water-soluble polymer, poly[(chloromethoxytrialanine methyl ester)phosphazene] (poly-Tame), was characterized and evaluated using high-performance size-exclusion chromatography, gradient reversed-phase high-performance liquid chromatography and ion chromatography. These novel liquid chromatographic methods were validated for application to in vitro biodegradation experiments of poly-Tame in aqueous solutions. Results from method validation experiments are presented.

Biodegradation, Environmental↗
PubMed1991

Identification of aromatic moieties and mycosamine in antifungal heptaenes with high-performance liquid chromatography, high-performance liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry.

A high-performance liquid chromatographic (HPLC) method for the determination of the aromaticity of heptaene polyene antibiotics has been developed. The released aromatic moiety of the heptaene polyenes aureofungin, candicidin, candimycin, hamycin and trichomycin was assayed after alkaline hydrolysis. The presence of p-aminoacetophenone (PAAP) and N-methyl-p-aminoacetophenone (N-methyl-PAAP) in the hydrolysates was determined by HPLC, HPLC-mass spectrometry (HPLC-MS) and gas chromatography-MS (GC-MS). Candicidin and hamycin contained only the PAAP residue; aureofungin contained both PAAP and N-methyl-PAAP. Trichomycin contained PAAP and also some unknown component of molecular weight 179. The aromatic nature of the individual components of the heptaene complex was demonstrated using radioactivity flow detection for the determination of the incorporation of [14C]-p-aminobenzoic acid to individual candicidin components. Ammonia chemical ionization MS was successfully used for the GC-MS identification of the acetylated mycosamine moiety of heptaenes.

4-Aminobenzoic Acid↗
PubMed1990

Preparative high-performance liquid chromatography and preparative thin-layer chromatography isolation of tocainide carbamoyl-O-beta-D-glucuronide: structural characterization by gas chromatography-mass spectrometry and fast atom bombardment-mass spectrometry.

Tocainide carbamoyl-O-beta-D-glucuronide, a major urinary metabolite of the antiarrhythmic drug tocainide [2-amino-N-(2',6'-xylyl)propanoxylidide], was isolated by preparative-TLC and preparative-HPLC. The isolated glucuronide was hydrolyzed in sodium hydroxide (pH greater than 12) to 3-(2',6'-xylyl)-5-methylhydantoin. This hydantoin product was also identified when tocainide was reacted with urea in urine. Structural characterization of the isolated tocainide glucuronide was carried out using GC-MS of the permethylated derivative. The molecular ion of the permethylated glucuronide was not observed, but ion fragments at m/z 232(244), 277(288), and 334(349) were found to correspond to the postulated novel carbamoyl ester structure of the permethylated (perdeuteromethylated) glucuronide. Structural evidence for the underivatized tocainide glucuronide was obtained using fast atom bombardment-MS. The [M + H]+ ion at m/z 413 was observed. Characteristic sodium ion adducts [M + Na]+ and [M-H + 2Na]+ were also observed at m/z 435 and 457, respectively.

Anti-Arrhythmia Agents↗
PubMed1990

Transient expression of type 2 chain in A-active hexaglycosylceramide of rat small intestine at weaning time. Demonstration by affinity chromatography and ceramide glycanase hydrolysis of A-active glycosphingolipids followed by gas chromatography and mass spectrometry of permethylated hexasaccharides.

The small intestine of 15- to 23-day-old rats was cut into four segments from the duodenum to the ileum. Neutral glycosphingolipids were purified from each segment and submitted to thin-layer chromatography and immunostaining with the A005 monoclonal anti-A antibody. This antibody detected an hexaglycosylceramide located mainly in the duodenum during the postnatal development. In order to characterize hexaglycosylceramides, blood group A-active glycolipids were purified by affinity chromatography on immobilized Helix pomatia lectin in organic solvent. Hexaglycosylceramides (A-6) were subsequently isolated by preparative thin-layer chromatography and hydrolyzed with ceramide glycanase. The free hexasaccharides were permethylated and analyzed by gas chromatography. Two peaks were detected in varying ratios during development, corresponding to type 1 and type 2 chain A hexasaccharides. Gas chromatography clearly demonstrated that type 2 A-6 occurred in the duodenum of developing rats, and that a shift from type 2 to type 1 A-6 occurred with growing age. The change from type 2 to type 1 chain was also assessed by methylation analysis, and by the variation of the characteristic fragmentations of type 1 and type 2 chain hexasaccharides upon mass spectometry of the permethylated A-6 oligosaccharides from the duodenum of 19-day-old and adult rats.

Aging↗
PubMed1991

Purification of carbonic anhydrase isoenzymes by high-performance affinity chromatography and hydrophobic interaction chromatography.

Isoenzymes of carbonic anhydrase were purified by a combination of affinity chromatography and hydrophobic interaction chromatography. Immobilization of sulfonamides on an epoxy-activated support provided a stationary phase for affinity chromatography which was stable to hydrolysis by carbonic anhydrase. A first purification step allowed the isolation of enzymes directly from homogenates of human erythrocytes and rat stomach. Without any further preparation, except the addition of ammonium sulfate to the eluate from affinity chromatography, the isoenzymes could be separated by hydrophobic interaction chromatography with very high recovery of protein and retention of enzymatic activity.

Animals↗
PubMed1979

Identification of vitamin D3 and 7-dehydrocholesterol in cow's milk by gas chromatography-mass spectrometry and their quantitation by high-performance liquid chromatography.

Identification of vitamin D3 and 7-dehydrocholesterol (7-DHC) in cow's milk by gas chromatography-mass spectrometry (GC-MS) and their quantitation by high-performance liquid chromatography (HPLC) were investigated. When vitamin D and provitamin D fractions purified from a sample of commercial cow's milk were applied to GC-MS, the results showed that the fractions contained vitamin D3 and 7-DHC, respectively, while neither vitamin D2 nor ergosterol could be detected in the milk. HPLC methods for the determination of vitamin D3 and 7-DHC in cow's milk were then proposed as routine methods. The method for assaying vitamin D3 included the isolation of lipids from milk according to the directions of Bell and Christie (5), saponification, isolation of unsaponifiable matter, digitonin-Celite column chromatography, preparative thin-layer chromatography (TLC) and application to HPLC. On the other hand, 7-DHC in milk could be simultaneously determined without the purification by digitonin-Celite column chromatography. The peak corresponding to either vitamin D3 or 7-DHC in the respective HPL-chromatograms was clearly separated from possible interfering substances and the recovery experiments for both vitamin D3 and 7-DHC gave satisfactory results. When the proposed methods were applied to 10 samples of commercial cow's milk, the assayed values of vitamin D3 and 7-DHC were 19--79 I.U./liter and 14--56 microgram/liter, respectively.

Animals↗
PubMed1992

Solid-phase extraction techniques for the determination of glycopyrrolate from equine urine by liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry.

Glycopyrrolate (Robinul) is a quaternary ammonium salt which serves as a respiratory enhancing drug. It is reportedly used in horse racing to improve breathing. Extraction of glycopyrrolate from equine urine employing unique solid-phase extraction techniques gave a residue suitable for liquid chromatography-tandem mass spectrometry (LC-MS-MS) and gas chromatography-mass spectrometry (GC-MS). LC-MS-MS analysis employed an extract derived from 5 ml of urine subjected to cation-exchange chromatography. The daughter ion of m/z 318 monitored in the positive-ion mode was m/z 116. Recovery of glycopyrrolate was 99.5% and the within-run coefficient of variation of two quality control samples (1.0 and 10 ng/ml) was less than 5%. The between-run coefficient of variation for the same two quality control samples was less than 6.5%. The minimal detectable concentration for the assay was 250 pg/ml. Due to the extremely low concentration of glycopyrrolate in urine, qualitative detection via full-scan GC-MS required XAD-2 extraction of 50 ml of urine, cation-exchange chromatography clean-up and a tandem hydrolysis-derivatization procedure. The target analyte for GC-MS qualitative analysis was the methyl ester of hydrolyzed glycopyrrolate. Glycopyrrolate could be detected in post-administration (1 mg intravenously) urine samples for up to 9 h by both LC-MS-MS and GC-MS. The success of the method was due to a combination of the extreme sensitivity of the LC-MS-MS method and the very selective extraction process for quaternary ammonium salts.

Animals↗
PubMed1992

Determination of nalbuphine using high-performance liquid chromatography coupled to photodiode-array detection and gas chromatography coupled to mass spectrometry.

A procedure involving capillary column gas chromatography coupled to mass spectrometry and a method involving liquid chromatography coupled to a diode-array detector have been developed for the analysis of nalbuphine. The extraction step is the same for both techniques and involves extraction under alkaline conditions in chloroform-2-propanol-n-heptane (50:17:33, v/v/v) with levallorphan as the internal standard. After purification by acidic extraction and back alkaline extraction, drugs are derivatized with N,O-bis-(trimethylsilyl)trifluoroacetamide with 1% trimethylchlorosilane for gas chromatography-mass spectrometry and directly injected for high-performance liquid chromatography-diode-array detection. The limits of detection are 2.0 and 25.0 ng/mg, respectively.

Chromatography, High Pressure Liquid↗
PubMed1978

Specific method for determining uric acid in serum using high-performance liquid chromatography and gas chromatography-mass spectropmetry.

A method using a combination of high-performance liquid chromatography and stable-isotope dilution-mass spectrometry is described for the specific quantitation of uric acid in serum. The procedure involves addition of a known amount of [1,3,9-15n]uric acid, as intenral standard, to the serum sample followed by equilibration with the endogenous analyte. After separation from serum proteins, cationic and neutral compounds by anion-exchange chromatography, the purified uric acid is converted into its tetraethyl derivatives. High-performance liquid chromatography is used to isolate the three major isomeric derivatives for measurement of the isotope ratio m/e 280 to m/e 283. This ratio gives the relative abundances of the molecular ions of natural and of labelled tetraethyluric acid, and from it the amount of uric acid in the original serum specimen is determined. Effective separation of tetraethyluric acid isomers can be achieved by adsorption or reversed-phase high-performance liquid chromatography using n-heptane-isopropanol (80:1, v/v) and methanol-water (3:2, v/v), respectively, as solvent systems.

Adsorption↗
PubMed1990

Purification of the IL-2 receptor (TAC) by ligand-affinity chromatography and utilization of the immobilized receptor for receptor-affinity chromatography (RAC) purification of IL-2, mutant IL-2, and IL-2 fusion proteins.

Recombinant technology has facilitated the production of two soluble forms of human p55 interleukin-2 receptor (IL-2R) in Chinese hamster ovary cells. We have developed a ligand-affinity method for the medium-scale purification of these two soluble forms of the IL-2R, based on the biochemical interactions between the matrix-bound ligand (interleukin-2) and its soluble receptor. The affinity-purified IL-2R is further purified by anion-exchange chromatography followed by gel filtration. This method has provided enough highly pure IL-2R for structure and function studies and for use in practical applications such as high-flux drug-screening assays. The purified IL-2R subsequently has been immobilized on silica gel and employed for the purification of recombinant IL-2. Receptor-affinity-chromatography-purified IL-2 contains only a highly active monomeric form of the lymphokine, in contrast to immunoaffinity chromatography where several molecular forms of IL-2 with varying degrees of biologic activity are recovered. Receptor-affinity chromatography has been successfully applied to the purification of several mutant IL-2 as well as an IL-2-Pseudomonas exotoxin (IL2-PE40) fusion protein that is a 54.5-kDa chimeric protein in which the cell recognition domain is replaced by IL-2. The IL-2-PE40 is a potential cytotoxic agent for cells bearing the IL-2 receptor.

ADP Ribose Transferases↗
PubMed1976

[Point of micropreparative high pressure liquid chromatography and thin-layer chromatography for the identification of indole compounds in human plasma (author's transl)].

Results are presented on the analysis of indolic metabolites of tryptophan in human plasma, using high-pressure liquid chromatography and thin-layer chromatography. Dichloromethane/ethanol extracts of denaturated plasma were analysed. Thin-layer chromatography proved to be more advantageous for the analysis of this class compounds because it is possible to use a specific staining reagent (4-dimethylaminobenzaldehyde). The advantage of high-pressure liquid chromatography lies in the rapid isolation and purification of unknown compounds for identification in an off-line method. This application is demonstrated with the isolation of N-acetyltryptophan from human plasma. Preliminary results are presented on the plasma concentration of indole-3-lactic acid, indole-3-acetic acid and N-acetyltryptophan in healthy persons, phenylketonurics, and uremic patients.

Adolescent↗
PubMed1978

Comparative determination of phenytoin by spectrophotometry, gas chromatography, liquid chromatography, enzyme immunoassay, and radioimmunoassay.

Sera from patients being treated with phenytoin were analyzed for the drug by spectrophotometry, gas chromatography, radioimmunoassay, enzyme immunoassay, and liquid chromatography. The essay values obtained were intercompared statistically. Enzyme immunoassay and liquid chromatography appear to be attractive alternatives to the more traditional methods of spectrophotometry and gas chromatography. Our radioimmunoassay data correlated poorly with results by the four other methods.

Chromatography, Gas↗
PubMed1979

Analysis for diazepam and nordiazepam by electron-capture gas chromatography and by liquid chromatography.

We describe the use of electron-capture gas chromatography or reversed-phase "high-performance" liquid chromatography for concurrent analysis for diazepam and nordiazepam in serum. In the gas-chromatographic analysis our use of a new chemically deactivated stationary liquid phase, SP 2250-DB (Supelco, Inc.), resulted in improved chromatographic sensitivity and peak symmetry for the two benzodiazepines as compared to that obtained with either OV-17or OV-1 phases. Steady-state concentrations of diazepam and nordiazepam in serum as determined by gas-liquid chromatography correlated closely with those found by liquid-liquid chromatography.

Chromatography, Gas↗