A rapid and simple extraction procedure followed by gas chromatography using a nitrogen detector is described for the analysis of amitriptyline, nortriptyline, imipramine, and desipramine in 100 μl plasma. No derivitisation of the drugs is required. Recoveries ranged from 93·7 to 104·6%. Within-batch precision and day-to-day variation showed coefficients of variation of less than 10% with the exception of desipramine, for which the day-to-day coefficient of variation was 15·2%. The method was developed to measure plasma concentrations in patients who had taken non-fatal and fatal overdoses of the drugs.
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