A Modified Simple and Rapid Reversed Phase High Performance Liquid Chromatographic Method for Quantification of Amitriptyline and Nortriptyline in Plasma

A simple and rapid reversed-phase liquid chromatographic method for the determination of amitriptyline and nortriptyline in plasma is described. Protriptyline was used as internal standard. Plasma samples were extracted from alkaline pH with hexane-isoamylalcohol 98:2 v/v for 60 sec on a vortex apparatus. The organic phase was back extracted with HCl 0.1N and the aqueous phase was injected directly and monitored at 240nm. Samples were chromatographed on a 5 μm Kromasil 100-C8 column (25 cm × 4 mm i.d) using acetonitrile/0.04M KH2PO4 40:60 v/v as the mobile phase. The lower limit of detection was 5 ng/ml for amitriptyline and nortriptyline while the lower limit of quantification was 10 ng/ml for both compounds. Peak height and plasma amitriptyline or nortriptyline concentrations were linearly related from 25 to 300 ng/ml. No potential sources of interference have been identified. The methodology was used to monitor plasma amitriptyline or nortriptyline concentrations in patients receiving therapeu...