Methods for the estimation of the tricyclic antidepressants in plasma have been described employing UV spectrophotometry', gas-liquid chromatographyz4, and mass fragmentography5-6.
UV methods, while adequate for analysis in cases of overdose, are insufficiently sensitive where plasma IeveIs are required in the therapeutic range. Several GLC methods are available*-', but the requirement for a lengthy clean-up procedure and the necessity for derivative formation make these methods too time consuming for emergency use and expensive in terms of operator time for routine therapeutic screening.
Following on the methods developed for determining these compounds7ss, we wished to produce a method, applicable to both plasma and urine, which was capable of estimating both amitriptyline and nortriptyline on a 2-ml sample of plasma with a rapid extraction procedure. This has now been achieved.
EXPERIMENTAL
Materials
Dichloromethane was obtained from Rathburn Chemicals (Walkerburn, Peebleshire, Great Britain). Ethanol was BDH Aristar grade (BDH, Poole, Great Britain). All other chemicals were BDH Analar grade. Amitriptyline, nortriptyline, and desmethylimipramine were given by Dr. hl. Turnbull and Mr. R. Sparks of the