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.

Monitoring 2-ethyl-2-phenylmalonamide in serum by gas-liquid chromatography: application to retrospective study in epilepsy patients dosed with primidone.

1980 ◽  
Vol 26 (11) ◽  
pp. 1537-1539 ◽  
Author(s):  
D Haidukewych ◽  
E A Rodin
Keyword(s):  
Liquid Chromatography ◽  
Steady State ◽  
Retrospective Study ◽  
Seizure Control ◽  
Internal Standard ◽  
Gas Liquid Chromatography ◽  
Sensitivity Limit ◽  
Group A ◽  
The Mean ◽  
Group B

Abstract We describe a procedure for determining 2-ethyl-2-phenylmalonamide (I) in serum of epilepsy patients dosed with primidone (II) for seizure control, by extracting the sample with chloroform under basic conditions, with use of an internal standard, 2-ethyl-2-(p-tolyl)malonamide, and without derivative formation. The sensitivity limit is 1.0 mg/L. Within-run CVs for 5, 10, and 30 mg/L concentrations were 3.5, 2.5, and 0.7%, respectively. For a 1.0 mg/kg body wt per day dose of II in patients co-medicated with phenytoin (Group A), the mean steady-state concentrations of I, II, and phenobarbital (III) were 0.72, 0.62, and 2.24 mg/L, respectively. For patients co-medicated with carbamazepine and phenytoin (Group B), I, II, and III concentrations were 0.68, 0.44, and 2.12 mg/L, respectively. Between these groups, only for II were the concentrations statistically different (t = 2.762; p < 0.01). For Group A no correlation was found between II and III. For Groups A and B, the coefficients of correlation between I and III were 0.626 and 0.826, respectively.

Determination of plasma procainamide and N-acetylprocainamide concentration by high-pressure liquid chromatography.

1977 ◽  
Vol 23 (7) ◽  
pp. 1318-1320 ◽  
Author(s):  
J S Dutcher ◽  
J M Strong
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Antiarrhythmic Drug ◽  
Chromatographic Analysis ◽  
Active Metabolite ◽  
Internal Standard ◽  
Routine Method ◽  
Simple Extraction ◽  
The Mean

Abstract We describe a routine method for determining concentrations of the antiarrhythmic drug procainamide and its active metabolite, N-acetylprocainamide, in plasma. A simple extraction of 1.0 ml of plasma is followed by separation and chromatographic analysis by use of a column containing microparticulate silica. p-nitro-N-(2-diethylaminoethyl)benzamide hydrochloride was synthesized and used as the internal standard. Total chromatographic time is only 7 min. The day-to-day CV during three months of daily use was less than 4% of the mean for each compound, and we saw no deterioration in column performance during this time. Phenobarbital, phenytoin, lidocaine, primidone, methsuximide, quinidine, and their metabolites do not interfere.

Measurement of thiamylal and thiopental in plasma by electron capture and flame photometric gas-liquid chromatography.

1977 ◽  
Vol 23 (7) ◽  
pp. 1306-1309 ◽  
Author(s):  
R H Smith ◽  
J A MacDonald ◽  
D S Thompson ◽  
W E Flacke
Keyword(s):  
Liquid Chromatography ◽  
Ethyl Acetate ◽  
Electron Capture ◽  
Internal Standard ◽  
Chromatographic Column ◽  
Gas Liquid Chromatography ◽  
Unchanged Drug ◽  
Chromatographic Procedure ◽  
Isothermal Gas ◽  
Liquid Chromatographic

Abstract We describe an isothermal gas-liquid chromatographic procedure developed for measuring thiamylal and thiopental in plasma. The unchanged drug is extracted into ethyl acetate from acidified plasma, together with an internal standard. The solvent is removed, the residue methylated, aliquots, diluted with benzene, are injected into a 183-cm gas-liquid chromatographic column containing 3% OV-17. Sensitivity of detection is in the nanogram to picogram range.

DETERMINATION OF DEHYDROEPIANDROSTERONE AND DEHYDROEPIANDROSTERONE SULPHATE IN HUMAN PLASMA USING ELECTRON CAPTURE DETECTION OF 4-ANDROSTENE-3,6,17-TRIONE AFTER GAS-LIQUID CHROMATOGRAPHY

1972 ◽  
Vol 53 (3) ◽  
pp. 461-474 ◽  
Author(s):  
F. H. de JONG ◽  
H. J. van der MOLEN
Keyword(s):  
Liquid Chromatography ◽  
Electron Capture ◽  
Plasma Concentrations ◽  
Mean Value ◽  
Electron Capture Detection ◽  
Gas Liquid Chromatography ◽  
Mean Values ◽  
Peripheral Plasma ◽  
Competitive Protein Binding ◽  
The Mean

SUMMARY A method for the measurement of dehydroepiandrosterone (DHA) and of its sulphate (DHAS) in human peripheral plasma is described and evaluated. After isolation of DHA from the sample the steroid is oxidized to 4-androstene-3,6,17-trione, which is measured with an electron capture detector after gas—liquid chromatography. It is possible to detect 100 pg 4-androstene-3,6,17-trione. The smallest amount of DHA per sample that can be distinguished from zero is approximately 4 ng, when recovery (27·9 ± 8·8%) and method blank (0·23 ± 0·38 ng) are taken into account. The oxidation to 4-ene-3,6-diones is specific for steroidal 5-en-3-ols. Specificity for DHA is ensured by several chromatographic steps. Repeated estimation of 10 ng DHA gave a mean value of 9·6 ± 1·45 (s.d.) ng (n = 35). Mean concentrations and their standard deviations for DHA and DHAS in peripheral plasma from 18 individuals were 0·50 ± 0·25 and 78 ± 40 μg/100 ml, respectively, at 08.30 h and 0·32 ± 0·17 and 84 ± 34 μg/100 ml, respectively, at 17.00 h of the same day. Levels of plasma cortisol in the same plasma samples estimated with a competitive protein-binding method were 16·7 ± 1·8 and 11·9 ± 3·8 μg/100 ml, respectively. No significant differences between the sexes were observed by any of the three assays. The mean values of the plasma concentrations of cortisol and DHA in the morning were significantly higher than those in the evening (P < 0·001 and P < 0·005, respectively). In contrast, the mean value of the plasma levels of DHAS in the morning was significantly lower than that in the evening (P < 0·025).

scholarly journals Measurement of 5-aminolaevulinate synthase activity by gas-liquid chromatography with electron-capture detection

1990 ◽  
Vol 270 (1) ◽  
pp. 103-107 ◽  
Author(s):  
A Gorchein
Keyword(s):  
Enzyme Activity ◽  
Liquid Chromatography ◽  
Electron Capture ◽  
Rat Liver ◽  
Ethyl Acetoacetate ◽  
Human Lymphocytes ◽  
Internal Standard ◽  
Electron Capture Detection ◽  
Gas Liquid Chromatography ◽  
Specific Assay

A specific assay for 5-aminolaevulinate synthase activity is described, with a sensitivity comparable with that of radiochemical assays. It is based on measurement by g.l.c. with electron-capture detection of the pentafluorobenzyl ester of the ethyl acetoacetate pyrrole derivative of 5-aminolaevulinic acid, and of the corresponding compound from 6-amino-5-oxohexanoic acid used as internal standard. Enzyme activity has been measured in homogenates of rat liver, spleen, kidney and brain, and in human lymphocytes.

Micromethod for measuring hexachlorophene in whole blood by gas-liquid chromatography.

1977 ◽  
Vol 23 (6) ◽  
pp. 944-947 ◽  
Author(s):  
W E Dodson ◽  
E E Tyrala ◽  
R E Hillman
Keyword(s):  
Liquid Chromatography ◽  
Electron Capture ◽  
Whole Blood ◽  
Internal Standard ◽  
Repeated Measurements ◽  
Electron Capture Detector ◽  
Gas Liquid Chromatography

Abstract We describe a micromethod for measuring hexachlorophene by use of gas-liquid chromatography with a 63Ni electron capture detector. The procedure requires 100 micronl of blood for extractions of hexachlorophene, and dichlorophene is added as an internal standard. CV is 3.4% over the concentration range of 500 to 1300 microng of hexachlorophene per liter of whole blood. This procedure permits repeated measurements of hexachlorophene in newborns who are being washed with soap containing hexachlorophene.

Rapid Determination of Butylated Hydroxyanisole, tert-Butylhydroquinone, and Propyl Gallate in Edible Oils by Electron Capture Gas-Liquid Chromatography

1976 ◽  
Vol 59 (6) ◽  
pp. 1208-1212 ◽  
Author(s):  
B Denis Page ◽  
Barry P C Kennedy
Keyword(s):  
Liquid Chromatography ◽  
Electron Capture ◽  
Propyl Gallate ◽  
Edible Oils ◽  
Rapid Determination ◽  
Internal Standard ◽  
Butylated Hydroxytoluene ◽  
Gas Liquid Chromatography ◽  
Low Levels

Abstract A rapid method is described for the determination of 2- and 3-tert-butyl-4-hydroxyanisole (2- and 3-BHA), tert-butylhydroquinone (TBHQ), and propyl gallate (PG) as their heptafluorobutyrates in edible oils. A solution of the oil in ether-benzene is treated with heptafluorobutyric anhydride (HFBA) in the presence of trimethylamine as catalyst. Excess HFBA is destroyed and a suitably diluted aliquot is analyzed by electron capture gas-liquid chromatography. An internal standard is added before derivatization to aid quantitation and identification of the antioxidants. Average recoveries from an oil spiked at 1, 5, 5, and 5 ppm TBHQ, 2-BHA, 3-BHA, and PG were 110, 105, 106, and 102%, respectively. At these low levels, however, some late-eluting peaks interfered. Butylated hydroxytoluene is not determined by this method.

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.

Micromethod for determination of diazepam by electron-capture gas-liquid chromatography.

1977 ◽  
Vol 23 (7) ◽  
pp. 1338-1339 ◽  
Author(s):  
E Rey ◽  
J M Turquais ◽  
G Olive
Keyword(s):  
Liquid Chromatography ◽  
Electron Capture ◽  
Diethyl Ether ◽  
Internal Standard ◽  
Electron Capture Detector ◽  
Gas Liquid Chromatography

Abstract We used 100 microliters of plasma for the determination of diazepam. After the internal standard, prazepam, is added, the serum is directly extracted with diethyl ether, the extract is evaporated, the residue is dissolved in ethanol, and the drug is measured by gas-liquid chromatography, with use of an electron capture detector. With this procedure, 2.5 ng of diazepam in the sample can be speedily measured with specificity, accuracy, and reproducibility (CV = 4.5%).

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