Simultaneous determination of norethisterone and six metabolites in human plasma by capillary gas chromatography with mass-selective detection.
A method for the simultaneous determination of norethisterone (NET) and six metabolites in human plasma by capillary gas chromatography-mass-selective detection (GC-MS) is described. The compounds are determined in plasma after enzymatic hydrolysis. After addition of norgestrel as the internal standard, the compounds are extracted from plasma at pH 5 using an Extrelut column and elution with dichloromethane. After evaporation, the compounds are converted into bistrimethylsilyl derivatives which are determined by gas chromatography using a mass-selective detector at m/z 429 for the two dihydro-NET (5 beta-NET and 5 alpha-NET), m/z 431 for the four tetrahydro-NET (3 alpha,5 alpha-NET, 3 beta,5 beta-NET and 3 beta,5 alpha-NET), m/z 442 for NET and m/z 456 for the internal standard. The reproducibility and accuracy of the method were found suitable over the range of concentrations between 0.50 and 8 ng/ml for NET, and metabolites except for 5 alpha-dihydro-NET (between 1 and 8 ng/ml). The method was applied to clinical samples.
Pommier
F
F
Laboratoires Ciba-Geigy, Bioanalytics and Pharmacokinetics, Rueil Malmaison, France.
Sioufi
A
A
Godbillon
J
J
D002138:Calibration; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D013058:Mass Spectrometry; D009640:Norethindrone / Q000097:blood*; D011786:Quality Control; D012680:Sensitivity and Specificity
D009640:Norethindrone