HPLC of sertraline and norsertraline in plasma or serum

A simple method for the measurement of sertraline and norsertraline in plasma or serum suitable for use in single-dose pharmacokinetic studies has been developed. Internal standard solution, aqueous fenethazine (10 mg/L) (20 microL), and Tris buffer (2 mol/L), pH 10.6) (100 microL) were added to plasma (200 microL). Sertraline, norsertraline and the internal standard were extracted into methyl tert-butyl ether (200 microL) by mixing (30 s) and centrifugation (11,000 r.p.m., 4 min). A portion (100 microL) of the extract was injected onto a Spherisorb S5SCX HPLC column (150 x 4.6 mm i.d.) which was eluted with methanol:water (19 + 1) containing ammonium perchlorate (40 mmol/L), final pH 7.0. Detection was by UV monitoring (215 nm). The concentration of each analyte in each sample was calculated from the calibration graph (peak-height ratio of analyte to that of the internal standard against concentration) obtained after analysis of plasma samples containing known amounts of sertraline and norsertraline. The limit of accurate measurement of the assay was 10 micrograms/L) sertraline and 20 micrograms/L) norsertraline.