Monitoring diazepam and desmethyldiazepam concentrations in plasma by gas-liquid chromatography, with use of a nitrogen-sensitive detector.

1979 ◽  
Vol 25 (1) ◽  
pp. 137-140 ◽  
Author(s):  
A K Dhar ◽  
H Kutt
Keyword(s):  
Liquid Chromatography ◽  
Acid Hydrolysis ◽  
Active Metabolite ◽  
Mineral Acid ◽  
Gas Liquid Chromatography ◽  
Sensitive Detector ◽  
Reference Standard ◽  
Internal Reference ◽  
Internal Reference Standard ◽  
Pharmacologically Active

Abstract We describe a modified [from Anal. Chem. 36, 2099 (1964)] procedure for determining diazepam and its pharmacologically active metabolite, desmethyldiazepam, in plasma, with use of a nitrogen-sensitive detector in the gas-liquid chromatography. We used medazepam as the internal reference standard. Diazepam and desmethyldiazepam are converted to their respective benzophenones by mineral acid hydrolysis. With this procedure, as little as 100 muL of plasma can be used to determine the drug in concentrations as low as 10 microgram/L, accurately, reproducibly, and quickly. Within-run and between-run CVs for 100 microgram/L concentrations of the two compounds were 5 and 7%, respectively.

Monitoring clorazepate dipotassium as desmethyldiazepam in plasma by electron-capture gas--liquid chromatography.

1980 ◽  
Vol 26 (1) ◽  
pp. 142-144
Author(s):  
D Haidukewych ◽  
E A Rodin ◽  
R Davenport
Keyword(s):  
Liquid Chromatography ◽  
Electron Capture ◽  
Active Metabolite ◽  
Internal Standard ◽  
Gas Liquid Chromatography ◽  
Sensitivity Limit ◽  
One Step ◽  
The Mean ◽  
Pharmacologically Active ◽  
State Concentration

Abstract We describe a procedure for determing clorazepate dipotassium as its decarboxylated, pharmacologically active metabolite, desmethyldiazepam, in 100 microL of plasma, with use of electron-capture gas--liquid chromatography and with methylnitrazepam as the internal standard. The procedure is a one-tube, one-step extraction without derivative formation and is accurate, reproducible, and rapid. The sensitivity limit is 20 micrograms/L. Within-run and between-run CV's (concentration, 3.5 mg/L) were 2.9 and 3.5%, respectively. Within-run CV's for 1.5 and 1.0 mg/L concentrations were 3.9 and 4.3%, respectively. For a 1.0 mg/kg per day dose of clorazepate dipotassium, the mean steady-state concentration of desmethyldiazepam in plasma was 1.037 mg/L.

Monitoring clorazepate dipotassium as desmethyldiazepam in plasma by electron-capture gas--liquid chromatography.

1980 ◽  
Vol 26 (1) ◽  
pp. 142-144
Author(s):  
D Haidukewych ◽  
E A Rodin ◽  
R Davenport
Keyword(s):  
Liquid Chromatography ◽  
Electron Capture ◽  
Active Metabolite ◽  
Internal Standard ◽  
Gas Liquid Chromatography ◽  
Sensitivity Limit ◽  
One Step ◽  
The Mean ◽  
Pharmacologically Active ◽  
State Concentration

Abstract We describe a procedure for determing clorazepate dipotassium as its decarboxylated, pharmacologically active metabolite, desmethyldiazepam, in 100 microL of plasma, with use of electron-capture gas--liquid chromatography and with methylnitrazepam as the internal standard. The procedure is a one-tube, one-step extraction without derivative formation and is accurate, reproducible, and rapid. The sensitivity limit is 20 micrograms/L. Within-run and between-run CV's (concentration, 3.5 mg/L) were 2.9 and 3.5%, respectively. Within-run CV's for 1.5 and 1.0 mg/L concentrations were 3.9 and 4.3%, respectively. For a 1.0 mg/kg per day dose of clorazepate dipotassium, the mean steady-state concentration of desmethyldiazepam in plasma was 1.037 mg/L.

Evaluation of Gas-Liquid Chromatography in Assays for Blood Volatiles

1965 ◽  
Vol 11 (11) ◽  
pp. 1023-1035 ◽  
Author(s):  
Alan Mather ◽  
Angel Assimos
Keyword(s):  
Liquid Chromatography ◽  
Alcohol Concentration ◽  
Quantitative Assay ◽  
Gas Liquid Chromatography ◽  
Internal Reference ◽  
Detection And Identification ◽  
Large Populations ◽  
The Common ◽  
Low Levels ◽  
Better Than

Abstract A simple screening by gas-liquid chromatography (GLC) can provide definitive answers in the detection and identification of a number of volatile substances, including acetone and the common alcohols. After identification, quantitative assay by an internal-reference technic yields highly specific values for ethyl alcohol concentration with a precision at least equal to (and for low levels, better than) that of conventional assays. The unique advantage of GLC is in its simultaneous quantitative assay of mixtures, some of which cannot be satisfactorily assayed or even recognized in any other way. The combination of speed and negligible sample volumes render the technic valuable for sequential studies on capillary blood samples and, potentially, for mass screening of large populations.

scholarly journals Determination of Organosulfides from Onion Oil

Foods ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 884 ◽  
Author(s):  
Maranda S. Cantrell ◽  
Jared T. Seale ◽  
Sergio A. Arispe ◽  
Owen M. McDougal
Keyword(s):  
Diethyl Ether ◽  
Steam Distillation ◽  
Extraction Efficiency ◽  
Agricultural Products ◽  
Gas Chromatography Mass Spectrometry ◽  
Diallyl Disulfide ◽  
Reference Standard ◽  
Internal Reference ◽  
Internal Reference Standard

Qualitative and semi-quantitative analysis of organosulfides extracted from oil obtained by steam distillation of yellow onions was performed by gas chromatography-mass spectrometry (GC-MS). The extraction efficiency of organosulfides from onion oil was evaluated across four solvents: dichloromethane; diethyl ether; n-pentane; and hexanes. Analysis of solvent extracted organosulfides by GC-MS provided qualitative results that support the use of dichloromethane over other solvents based on identification of 27 organosulfides from the dichloromethane extract as compared to 10 from diethyl ether; 19 from n-pentane; and 17 from hexanes. Semi-quantitative evaluation of organosulfides present in the dichloromethane extract was performed using diallyl disulfide as the internal reference standard. Three organosulfides were detected in the extract at ≥5 mg/kg; 18 organosulfides between 3–5 mg/kg; and six organosulfides at <3 mg/kg. The E/Z isomers of 1-propenyl propyl trisulfide were among the most prevalent components extracted from the onion oil across all solvents; and 3,6-diethyl-1,2,4,5-tetrathiane was among the most abundant organosulfides in all solvents except hexanes. The method described here for the extraction of organosulfides from steam distilled onion oil surveys common solvents to arrive at a qualitative and semi-quantitative method of analysis for agricultural products involving onions; onion oil; and secondary metabolites of Allium spp.

scholarly journals Histogram score contributes for reliability of DNA content estimatives in Brachiaria spp

2012 ◽  
Vol 36 (6) ◽  
pp. 599-607
Author(s):  
Ana Luiza de Oliveira Timbó ◽  
Roselaine Cristina Pereira ◽  
Vanderley Borges dos Santos ◽  
Fausto Souza Sobrinho ◽  
Lisete Chamma Davide
Keyword(s):  
Flow Cytometry ◽  
Dna Content ◽  
Raphanus Sativus ◽  
Triploid Hybrid ◽  
Reference Standard ◽  
Internal Reference ◽  
Ploidy Levels ◽  
Buffer Solutions ◽  
Internal Reference Standard ◽  
Content Analyses

Flow cytometry allows to estimate the DNA content of a large number of plants quickly. However, inadequate protocols can compromise the reliability of these estimates leading to variations in the values of DNA content the same species. The objective of this study was to propose an efficient protocol to estimate the DNA content of Brachiaria spp. genotypes with different ploidy levels using flow cytometry. We evaluated four genotypes (B. ruziziensis diploid and artificially tetraploidized; a tetraploid B. brizantha and a natural triploid hybrid), three buffer solutions (MgSO4, Galbraith and Tris-HCl) and three species as internal reference standards (Raphanus sativus, Solanum lycopersicum e Pisum sativum). The variables measured were: histogram score (1-5), coefficient of variation and estimation of DNA content. The best combination for the analysis of Brachiaria spp. DNA content was the use of MgSO4 buffer with R. sativus as a internal reference standard. Genome sizes expressed in picograms of DNA are presented for all genotypes and the importance of the histogram score on the results reliability of DNA content analyses were discussed.

Amphetamines in Human Urine: Rapid Estimation by Gas—Liquid Chromatography

1970 ◽  
Vol 16 (9) ◽  
pp. 786-788 ◽  
Author(s):  
J W Schweitzer ◽  
A J Friedhoff
Keyword(s):  
Liquid Chromatography ◽  
Human Urine ◽  
Excretion Rate ◽  
Low Ph ◽  
Gas Liquid Chromatography ◽  
Reference Compound ◽  
Internal Reference ◽  
Rapid Estimation ◽  
Amphetamine Psychosis

Abstract A procedure is described for the quantitative determination of amphetamine and p-methoxyamphetamine and for the semiquantitative determination of methamphetamine, mephentermine, and normephentermine in human urine. An internal reference compound, phenethylamine, is added to 5 ml of urine. The urine is extracted at low pH to remove acidic contaminants, then at high pH with chloroform, in which the amines were acetylated with acetic anhydride. After evaporation, the residue, dissolved in dioxane, is injected onto a column at 215°C, packed with 8% ethyleneglycol adipate on Chromosorb W, 100-120 mesh, except at both ends, where the packing was 8% silicon rubber SE 30 on Chromosorb W, 100-120 mesh. The excretion rate of amphetamines by patients admitted with a diagnosis of amphetamine psychosis was measured.

Chemical and enzymatic variation in the cell walls of pathogenic Candida species

1985 ◽  
Vol 31 (7) ◽  
pp. 590-597 ◽  
Author(s):  
Frank L. Lyon ◽  
Judith E. Domer
Keyword(s):  
Liquid Chromatography ◽  
Acid Hydrolysis ◽  
Cell Walls ◽  
Gas Liquid Chromatography ◽  
Mild Acid Hydrolysis ◽  
Glucanase Activity ◽  
Commercial Preparation ◽  
Enzymatic Assays ◽  
Phenol Sulfuric Acid ◽  
Mild Acid

Cell walls, isolated from seven pathogenic species of Candida, were lipid extracted and fractionated by treatment with ethylenediamine or enzymatically hydrolyzed using chitinase and laminarinase. Two different chitinase preparations were used, one from Streptomyces sp. which had some β-1,3-glucanase activity, and another from Serratia marcescens which did not have glucanase activity. Laminarinase was a commercial preparation. The monosaccharide constituents of whole cell walls and the fractions derived from them were determined qualitatively and quantitatively by gas–liquid chromatography of the products of a mild acid hydrolysis and by the phenol – sulfuric acid assay of the products of a stronger acid hydrolysis. The monomeric constituents of the enzymatic hydrolyses were analyzed using gas–liquid chromatography. Approximately 50% of all walls was soluble in ethylenediamine. Glucose and mannose were the only monosaccharides found in all of the fractions derived from ethylenediamine extraction examined. Similarities among the strains, based upon relative amounts of glucose and mannose, were more apparent than differences, but statistical analyses of the data revealed a general trend of decreasing similarity in the following order, C. albicans and C. stellatoidea, C. tropicalis and C. parapsilosis, and C. pseudotropicalis, C. guilliermondii, and C. krusei. In the enzymatic assays, mannose and glucose were released by laminarinase, whereas glucose and N-acetyl-D-glucosamine or N-acetyl-D-glucosamine alone were released by the chitinases. These assays supported the trend in relationships cited above, with the data being somewhat more definitive.

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