ABSTRACT
Fluorouracil in human plasma of a concentration as low as 2 ng ml-1 can be assayed with the use of gas-liquid chromatography and a multiple ion detector. Fluorouracil is isolated from plasma by anion exchange extraction. The extract is butylated and the derivative obtained extracted into a mixture of cyclohexane + dichloromethane (95:5). An aliquot is submitted to combined gas-liquid chromatography mass spectrometry. The use of chlorouracil or oxygen-18 labelled fluorouracil as internal standard is discussed. Linearity is proven from 100 microgram to 5 ng of fluorouracil per ml plasma. The coefficients of variation are 7.2 and 8.4% for within-run and between-run precision, respectively, at the 50 ng ml-1 level. The biological applicability of our procedure is demonstrated by analysing plasma samples obtained at different time intervals from three patients given 1 g of fluorouracil once intravenously and once orally.
Subject(s)
Fluorouracil/blood , Gas Chromatography-Mass Spectrometry , Humans , Ion Exchange , Oxygen RadioisotopesABSTRACT
Combined gas chromatography-mass spectrometry with multiple-ion detection is used to quantitate vitamin D3 in plasma samples. Extensive cleanup of the plasma extract prior to analysis is required before mass fragmentographic analysis is possible, i.e., solvent extraction, digitonin precipitation, Lipidex column chromatography, and derivatization. Low resolution mass fragmentography is performed by monitoring simultaneously the molecular ions of the heptafluorobutyric esters of the all-trans isomer of vitamin D3 and dihydrotachysterol2, which is used as an internal standard. This new method uses 5 ml of plasma and it is specific and sensitive to 600 pg of vitamin D3. This assay shows that in plasma of normal adult subjects there is a vitamin D3 concentration of 5 to 11 ng/ml, lower than those values reported for biological and competitive protein binding assays. Specifically the method described offers potential as an eventual reference method.
Subject(s)
Cholecalciferol/blood , Gas Chromatography-Mass Spectrometry/methods , Adult , Animals , Cholecalciferol/standards , Cholesterol/blood , Fluorocarbons , Gas Chromatography-Mass Spectrometry/standards , Humans , Indicators and Reagents , Reference Standards , Reference ValuesABSTRACT
We report a fast, simple high-performance liquid-chromatographic assay for serum alpha-tocopherol, with use of a reversed-phase column and tocol as internal standard. Only 200 microliter of serum is required. Isocratic elution of the n-hexane extract is done within 6 min; total analysis time is less than 1 h. Within-day precision (CV) was 2.3% for 24 samples of a normal plasma pool (mean concn, 10.1 mg/liter). Day-to-day precision (CV) was 3.2%, measured for 20 days for a specimen with a concentration of 10.8 mg/liter. Analytical recovery of alpha-tocopherol from fortified serum was 89 to 100%. The lower detection limit of alpha-tocopherol is estimated to be 0.6 mg/liter. The specificity of the procedure was verified by spectrophotometry, gas-liquid chromatography, and combined gas chromatography/mass spectrometry of an eluate collected from the column.
Subject(s)
Vitamin E/blood , Chromatography, Gas , Chromatography, High Pressure Liquid , Evaluation Studies as Topic , Humans , Mass Spectrometry , MethodsABSTRACT
A procedure is described for the separation of Vitamin D and related compounds by gas-liquid chromatography using flame ionization detection. The method involves a two-step conversion: isomerization to the corresponding (all trans) isotachysterol(s) followed by methyl ether derivatization of the alcohol group(s). The procedure provides a means for identification as well as a possible basis for quantitation of Vitamin D and analogs.
Subject(s)
Chromatography, Gas/methods , Vitamin D/analysis , Chemical Phenomena , Chemistry , Cholecalciferol/analysis , Chromatography, Liquid , Hydroxycholecalciferols/analysis , Isomerism , Methods , Methyl Ethers/analysis , Vitamin D/analogs & derivativesABSTRACT
The presence of p-chlorophenoxyacetamide was detected in the urine of man receiving iproclozide [1-(p-chlorophenoxyacetyl)-2-isopropylhydrazine]. This new metabolite was identified by combined gas-liquid chromatography-mass spectrometry and by comparison with the synthetic compound. An appropriate procedure for the extraction and quantitation of p-chlorophenoxyacetamide by gas-liquid chromatography on a 5% OV-225-packed column with the 2-butyl analog of iproclozide as an internal standard, has been developed. After 20- and 50-mg single dose oral administrations of iproclozide, 5.2 and 8.3% were slowly excreted in urine as p-chlorophenoxyacetamide within 30.5 and 36 hr. respectively. After 20-mg oral intakes by psychiatric patients, the 24-hr urinary excretion of p-chlorophenoxyacetamide amounted to about 2-4% of the iproclozide dose administered.
