Sensitive method for the quantitation of nortriptyline and 10-hydroxynortriptyline in human plasma by capillary gas chromatography with electron-capture detection.
A method for the determination of nortriptyline and 10-hydroxynortriptyline concentrations in human plasma by capillary gas chromatography with electron-capture detection is described. The procedure requires 1.0 ml of plasma and uses maprotiline as an internal standard. The compounds are extracted from alkalinized plasma with hexane-2-butanol (98:2) and back-extracted into hydrochloric acid. The acid solution is then made basic and the compounds are re-extracted into n-butyl chloride. The extract is evaporated to dryness, derivatized with heptafluorobutyric anhydride, and analyzed by gas chromatography on a fused-silica capillary column coated with phenylmethyl silicone. The calibration curves for nortriptyline and 10-hydroxynortriptyline are linear in the ranges 3-40 and 7-90 micrograms/l, respectively, with coefficients of variation for within-day and between-day precision of less than 12%. The quantitation limits for nortriptyline and 10-hydroxynortriptyline are 1 and 3 micrograms/l, respectively. This procedure was used to analyze more than 1400 samples following sub-therapeutic doses of nortriptyline in human subjects. The assay was sufficiently sensitive for use in pharmacokinetic analysis.
Anliker
S L
SL
Lilly Research Laboratories, Eli Lilly & Company, Indianapolis, IN 46285.
Hamilton
M
M
Bopp
R J
RJ
Goldberg
M J
MJ
D002849:Chromatography, Gas; D004563:Electrochemistry; D006801:Humans; D007202:Indicators and Reagents; D009661:Nortriptyline / Q000031:analogs & derivatives* / Q000097:blood*
D007202:Indicators and Reagents; C013567:10-hydroxynortriptyline; D009661:Nortriptyline