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At least 271 records · Page 15Linked to original sources
PubMed1996

Comparison between gas chromatography-atomic emission detection and gas chromatography-mass spectrometry for the assay of propofol.

Quantitation by gas chromatography-atomic emission detection (GC-AED) is based on the intensity of the signal measured at a wavelength characteristic of an element, after atomisation by the plasma. This response depends only on the number of atoms of this element present in the molecule under investigation, and is independent of the structure of the molecule. This technique was used for the assay of propofol, and the estimation of its two metabolites, after calibration with standard solutions of pure propofol. The results were compared with those obtained by gas chromatography-mass spectrometry (GC-MS). Propofol was quantified with higher precision and accuracy by GC-AED than by GC-MS which exhibited larger residual values. Concentration assessment for two metabolites showed a better agreement with the theoretical value by GC-AED since the response depends only on the number of carbon atoms in each molecule.

Calibration↗
PubMed1996

Identification of a pyrovalerone metabolite in the rat by gas chromatography-mass spectrometry and determination of pyrovalerone by gas chromatography-nitrogen-phosphorus detection.

Pyrovalerone and its hydroxylated metabolite have been identified by gas chromatography-mass spectrometry in rat urine and plasma. A sensitive gas chromatographic method for the quantitative analysis of pyrovalerone in rat urine and plasma is described. The method also permits the quantitative monitoring of the urinary excretion of the drug and its metabolite. Pyrovalerone and its hydroxylated metabolite are detected up to 18 h after a single oral administration to the rat at a dose of 20 mg/kg.

Animals↗
PubMed2003

Solid-phase micro-extraction-gas chromatography-mass spectrometry and headspace-gas chromatography of tetrahydrocannabinol, amphetamine, methamphetamine, cocaine and ethanol in saliva samples.

In the present work, a method was developed aiming at the serial detection of tetrahydrocannabinol (THC), amphetamine, methamphetamine, cocaine and ethanol in saliva. Saliva samples were submitted to an initial headspace procedure for ethanol determination by gas chromatography/flame ionization detector (GC-FID). After this step, two consecutive solid-phase micro-extractions (SPME) were carried out: THC was extracted by submersing a polydimethylsiloxane fiber (100 micro m) in the vial for 20 min; amphetamine, methamphetamine and cocaine were subsequently extracted after alkalinization. Derivatization of the amphetamines was carried out directly in the solution by adding 2 micro l of butylchloroformate. Gas chromatography-mass spectrometry (GC-MS) was used to identify the analytes in selected ion monitoring (SIM) mode. Confidence parameters of validation of the method were: recovery, linearity, intra- and inter-assay precision as well as limits of detection and quantification of the analytes. The limits of quantification (LOQ) obtained were: ethanol (0.010 g/l); amphetamine (5.0 ng/ml); methamphetamine (0.5 ng/ml); cocaine (5 ng/ml) and THC (5 ng/ml). The method proved to be highly precise (coefficient of variation<8%) for all detected substances.

Amphetamine↗
PubMed2006

Evaluation of leaf-derived extracts as an environmentally sustainable source of essential oils by using gas chromatography-mass spectrometry and enantioselective gas chromatography-olfactometry.

In consideration of the world's present environmental situation and the threat of species extinction, investigations concerning alternative sustainable sources of natural substances represent an extremely important issue. In this respect, the present research is focused on the analytical evaluation of Brazilian rosewood (Aniba rosaeodora Ducke) leaves, as an alternative source (with respect to wood) of rosewood essential oil and, as such, of natural linalool, which is extensively used in perfumery. Enantioselective-gas chromatography-olfactometry (Es-GC-O) was used as a tool for the simultaneous stereodifferentiation and olfactive evaluation of the volatile optically active components present in the analyzed samples. In addition to Es-GC-O analyses, direct olfactive analyses were also performed, enabling the evaluation of the global aroma exerted by each sample and the influence of each linalool antipode, as also other minor compounds. The samples were also submitted to gas chromatography-mass spectrometric analysis, thus establishing their chemical profiles. The assessment of enantiopure chiral compounds through Es-GC-O, along with direct olfactive analyses, confirmed that the leaves are a potential substituent for wood in the extraction of Brazilian rosewood essential oil, representing a sustainable nonwood source of natural linalool.

Chromatography, Gas↗
PubMed1989

Characterization of glycosphingolipid mixtures with up to ten sugars by gas chromatography and gas chromatography-mass spectrometry as permethylated oligosaccharides and ceramides released by ceramide glycanase.

A novel, effective method for structural characterization of glycosphingolipids has been devised. It employs ceramide glycanase to release intact oligosaccharides followed by analysis using high-mass gas chromatography-mass spectrometry. The oligosaccharides and ceramides released by the glycanase were permethylated and analyzed. The capillary gas chromatography gave excellent resolution and separated, for example, two isomeric 10-sugar oligosaccharides with a molecular mass of 2150 daltons differing only by a Gal1-3GlcNAc and a Gal1-4GlcNAc linkage. The oligosaccharides released from sialic acid containing glycosphingolipids (gangliosides) were also analyzed for monosialo compounds. This analytical approach is simple, is quick, and can readily allow quantitation of individual glycosphingolipids.

Ceramides↗
PubMed2001

Aromatic profile of aqueous banana essence and banana fruit by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O).

Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to determine the aromatic composition and aroma active components of commercial banana essence and fresh banana fruit paste. Totals of 43 and 26 compounds were quantified in commercial banana essence and fresh banana fruit paste, respectively. Five new components in commercial banana essence were identified as methyl butyrate, 2,3-butanediol diacetate, 2-hydroxy-3-methylethylbutyrate, 1-methylbutyl isobutyrate, and ethyl 3-hydroxyhexanoate. A total of 42 components appear to contribute to the aromatic profile in banana. Isoamyl acetate, 2-pentanol acetate, 2-methyl-1-propanol, 3-methyl-1-butanol, 3-methylbutanal, acetal, isobutyl acetate, hexanal, ethyl butyrate, 2-heptanol, and butyl butyrate had high concentrations and were most detected by GC-O panelists in the commercial banana essence. Volatile components found only in fresh banana fruit paste that were detected by aroma panelists include E-2-hexenal, limonene, and eugenol.

Alcohols↗
PubMed2006

Comparison of aroma volatiles in commercial Merlot and Cabernet Sauvignon wines using gas chromatography-olfactometry and gas chromatography-mass spectrometry.

Seventy-four aroma active compounds were observed in Merlot and Cabernet Sauvignon wines produced in California and Australia. Volatiles were sampled using solid phase microextraction and analyzed using time-intensity gas chromatography-olfactometry and gas chromatography-mass spectrometry (GC-MS). The most intense odorants were 3-methyl-1-butanol, 3-hydroxy-2-butanone, octanal, ethyl hexanoate, ethyl 2-methylbutanoate, beta-damascenone, 2-methoxyphenol, 4-ethenyl-2-methoxy-phenol, ethyl 3-methylbutanoate, acetic acid, and 2-phenylethanol. Aroma compounds were classified according to their aroma descriptor similarity and summed into nine distinct categories consisting of fruity, sulfury, caramel/cooked, spicy/peppery, floral, earthy, pungent/chemical, woody, and green/vegetative/fatty. Both Merlot and Cabernet Sauvignon wines were characterized by high fruity, caramel, green, and earthy aroma totals. Although there were distinct quantitative differences between Merlot and Cabernet wines, the relative aroma category profiles of the four wines were similar. Of the 66 volatiles identified by GC-MS, 28 were esters and 19 were minor alcohols. Between 81 and 88% of the total MS total ion chromatogram peak areas from each wine type were produced from only eight compounds: ethanol, ethyl octanoate, ethyl decanoate, ethyl acetate, 3-methyl-1-butanol, ethyl hexanoate, diethyl succinate, and 2-phenylethanol. Merlot wines from both Australia and California contained 4-5 times more ethyl octanoate than Cabernet Sauvignon wines from the same sources.

Chromatography, Gas↗
PubMed1994

Determination of succinonitrile in horse urine by gas chromatography-nitrogen-phosphorus detector and gas chromatography-mass spectrometry.

A chromatographic method was developed to detect and confirm the presence of succinonitrile (SDN) in horse urine samples, for antidoping control. The urine samples (5 ml) were extracted with diethyl ether and screened by gas chromatography-nitrogen-phosphorus detector and the confirmation of the drug's presence was accomplished by using gas chromatography-mass selective detection. The recovery of extraction was 78 and 81% for 1.0 and 2.0 micrograms ml-1 (relative standard deviation, < 10%), respectively. Urine samples collected after the administration of Energisan were positive for SDN (1-30 h) in all samples analysed.

Animals↗
PubMedDate not supplied

Determination of fentanyl in whole blood at subnanogram concentrations by dual capillary column gas chromatography with nitrogen sensitive detectors and gas chromatography/mass spectrometry.

Two methods for the determination of fentanyl at subnanogram concentrations in whole blood have been developed and evaluated. The initial screening was by gas chromatography with nitrogen sensitive detection (GC/NPD) in a splitless injection onto two fused-silica, 0.32-mm i.d. capillary columns (5% and 50% phenyl methyl silicone). Confirmation was by gas chromatography/mass spectrometry (GC/MS) using selected ion monitoring of a splitless injection onto a 0.1-mm i.d., 0.34-microns 5% phenyl methyl silicone capillary column. The methods were studied at fentanyl concentrations over the range 0.05 to 5.0 ng/mL using 2 mL of blood. The detection limits were set at 0.10 ng/mL for GC/NPD and 0.05 ng/mL for GC/MS. The overall recovery of fentanyl was found to be greater than 75% over the range of 0.25 to 2.5 ng/mL. The within-run precision determined at fentanyl concentrations of 0.25 and 1.0 ng/mL showed coefficients of variation ranging from 8.7 to 14.8%. The between-run precision determined at concentrations of 0.4 and 0.8 ng/mL showed coefficients of variation ranging from 3.3 to 11.6%. The blood calibration curves in the range of 0.25 to 2.5 ng/mL monitored over a 3-month period showed a mean correlation coefficient of 0.99 for both the GC/NPD and GC/MS methods.

Analgesics, Opioid↗
PubMed1980

Profile analysis of total mycolic acids from skin corynebacteria and from named Corynebacterium strains by gas-liquid chromatography and gas-liquid chromatography/mass spectrometry.

Gas-liquid chromatography (g.l.c.) was investigated as a potential tool in the classification and identification of Cornyebacterium strains isolated from human skin, on the basis of the g.l.c. profile of the trimethylsilyl derivatives of their mycolic acid methyl esters. The g.l.c. patterns of five skin corynebacteria were compared with those of reference strains Corynebacterium diphtheriae PW8 and Corynebacterium xerosis NCTC 9755 and NCTC 7929. Further compositional information was obtained by gas-liquid chromatography/mass spectrometry (g.l.c./m.s.) of mycolates from C. diphtheriae PW8 and two of the skin isolates. In addition to identifying and examining the individual mycolate species and comparing the differences in mycolate profile between skin corynebacteria and between reference strains, a limited assessment was made of the possibility of distinguishing between organisms at both strain and species levels on the basis of mycolic acid composition as revealed by g.l.c. "fingerprinting".

Chromatography, Gas↗
PubMed1977

Non-polarographic blood gas analysis. II. In vivo evaluation of gas chromatograph system.

Evaluation of a new system, based on gas chromatography, providing arterial blood gas tensions without requiring drawn blood samples is continued in an animal model. A series of in vivo dog experiments is discussed evaluating flow dependence and other performance characteristics. Results confirm the laboratory bench performance reported earlier; clinical trials are now indicated.

Animals↗
PubMedDate not supplied

Determination of sucrose esters of fatty acids in food additive premixes by gas chromatography and confirmation of identity by gas chromatography/mass spectrometry.

A gas chromatographic (GC) method was developed for the determination of sucrose monoesters of fatty acids (mono-SuE) and sucrose acetate isobutyrate (SAIB) in food additive premixes. Mono-SuE and SAIB fractions were prepared by column chromatography with either a C8 or a silica gel solid-phase extraction column. The mono-SuE fraction was acetylated and applied to a wide-bore GC column (0.53 mm x 15 m) by splitless injection for determination. The SAIB fraction was applied to the GC column without derivatization. Gas chromatography/mass spectrometry was used to confirm the identity of GC peaks. The detection limits for mono-SuE and SAIB were 0.005 and 0.01%, respectively. Mono-SuE (C12, C14, C16, C18, and C18:1) and SAIB were found in commercial food additive premixes and some foods.

Chromatography, Gas↗
PubMed1986

Screening and quantification of hypnotic sedatives in serum by capillary gas chromatography with a nitrogen-phosphorus detector, and confirmation by capillary gas chromatography-mass spectrometry.

We describe a quantitative screen for hypnotic-sedative drugs in which we use capillary gas chromatography with a nitrogen-phosphorus detector (GC/NPD) as the primary method and capillary gas chromatography-mass spectrometry (GC-MS) for confirmation. GC retention times of the acid-extracted underivatized drugs were stable (CVs less than 1%), and the detector response varied linearly over a 20-fold concentration range with a mean correlation coefficient for 11 drugs of 0.989. The limits of detection were satisfactory (0.5 mg/L in a 0.5-mL serum sample and 1-microL injection volume), as were precision (average CV 5.2% within day, 6.4% between day). The complementary use of capillary GC-MS not only unambiguously confirms presumptive peaks identified by GC, but also prevents reports of false positives and identifies compounds not included in the quantitative GC screen that may be listed in the GC-MS library.

Amobarbital↗
PubMed1987

Oxybuprocaine and five metabolites simultaneously determined in urine by gas chromatography and gas chromatography-mass spectrometry after extraction with Extrelut.

We describe a gas-liquid chromatographic (GC) method for determination of oxybuprocaine, and a gas chromatographic-mass spectrometric (GC-MS) method for simultaneous determination of four of its nine metabolites in urine. We used an Extrelut column to simply and rapidly extract oxybuprocaine and its metabolites from urine. For the GC-MS analyses, we monitored the characteristic fragment ions at m/z 353, 395, 369, 411, and 235 for 3-butoxy-4-aminobenzoic acid (metabolite 2, M-2), 3-butoxy-4-acetylaminobenzoic acid (M-3), 3-hydroxy-4-aminobenzoic acid (M-4), 3-hydroxy-4-acetylaminobenzoic acid (M-5), and methaqualone (internal standard), respectively. We quantified the glucuronide of M-2 after enzymic treatment. The assay's selectivity and reproducibility (within-day and between-day CVs less than 8% for all metabolites) make it applicable to determine oxybuprocaine and its metabolites in human urine. Mean 9-h urinary excretion of oxybuprocaine and its five metabolites from four healthy volunteers was 89.2% after a 100-mg oral dose.

Chromatography, Gas↗
PubMed1981

Gas-liquid chromatographic and gas-liquid chromatographic-mass spectrometric determination of fenvalerate and permethrin residues in grasshoppers and duck tissue samples.

A procedure is described for determining fenvalerate and permethrin residues in grasshoppers and duck tissues. Samples are Soxhlet-extracted with hexane and cleaned up by gel permeation chromatography with an in-line alumina column. Samples are analyzed by gas-liquid chromatography with electron capture detection, and confirmed by gas-liquid chromatography-mass spectrometry. The average recovery from fortified tissues was 97%.

Animals↗
PubMedDate not supplied

Confirmation of chloramphenicol residues in egg by gas chromatography/high-resolution mass spectrometry and comparison of quantitation with gas chromatography-electron capture detection.

Determination of chloramphenicol (CAP) residues in egg by gas chromatography/high-resolution mass spectrometry (GC/HRMS) with negative chemical ionization and gas chromatography with electron capture detection (GC-ECD) is described. A cleanup based on acetonitrile extraction followed by solid-phase extraction with silica gel and gel filtration columns was developed for extraction of CAP residues from whole egg. For quantitation, the internal standards used were the meta isomer of CAP (m-CAP) for GC-ECD and both m-CAP and deuterium-labeled CAP (D5-CAP) for GC/HRMS. For GC/HRMS, evaluation was performed by selecting characteristic ions at m/z 466 for CAP and m-CAP and at m/z 471 for D5-CAP. Both methods were validated with egg samples fortified at 0.4-2.0 micrograms/kg and lyophilized egg samples from animals treated at the 1 microgram/kg concentration level. The coefficient of variation was below 10%. Limits of detection and quantitation of both methods were about 0.3 and 0.5 microgram/kg, respectively. For confirmation of CAP residues, the relative ion abundance (m/z 466 and 468) was calculated. Further confidence was obtained by comparison of accurate monoisotopic masses from a spectrum library.

Anti-Bacterial Agents↗
PubMed1993

Automated sample preparation by on-line dialysis and trace enrichment. Analysis of morphine, 6-monoacetylmorphine, codeine, ethylmorphine and pholcodine in plasma and whole blood by capillary gas chromatography and capillary gas chromatography-mass spectrometry.

A fully automated sample preparation method for the determination of five opiates in human plasma and whole blood is described. The technique combines dialysis and trace enrichment prior to gas chromatography and gas chromatography-mass spectrometry. Dialysis and trace enrichment on a polymer column was shown to be a highly reliable method for sample preparation. The method can be used, after minor modification, to determine other basic drugs in plasma and whole blood. The method demonstrates the potential of the automated sequential trace enrichment of dialysate (ASTED) system for automated sample preparation.

Automation↗
PubMed1977

Use of new silylating agents for identification of hydroxylated steroids by gas chromatography and gas chromatography mass spectrometry.

Differences in methylene unit values were used for the determination of the hydroxyl group number of a steroid by means of gas chromatography. This index is defined as the difference in the methylene unit value between trimethylsilyl and other dimethylalkylsilyl (DMAS) ether derivatives of hydroxylated steroids, namely dimethylethylsilyl (DMES) and dimethyl-n-propylsilyl (DMPS) ethers. The reactivities of DMES and DMPS imidazoles as silylating agents were nearly equal to that of TMS-I. Mass spectra of these derivatives were characterized by the molecular ion cluster, [M]+., [M-15]+ and [M-29]+ (or [M-43]+). The molecular ion cluster of these derivatives is most useful for estimating the molecular weight. Therefore, these DMAS ethers provide valuable information for structural elucidation of hydroxylated steroids by gas chromatography electron impact mass spectrometry.

Chromatography, Gas↗