HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF TRAZODONE AND 1-M-CHLOROPHENYLPIPERAZINE WITH ULTRAVIOLET AND ELECTROCHEMICAL DETECTOR

A high-performance liquid chromatographic (HPLC) assay was developed f or the determination of trazodone and its metabolite, 1-m-chlorophenyl piperazine (m-CPP), in plasma. The high level of trazodone in plasma w as detected by ultraviolet absorbance at 254 nm and the low level of m -CPP in plasma was detected by coulometric electrochemical detection a t 840 mV on the series arrangement of two detectors. Pilsicainide as a n internal standard for both compounds was monitored by both detectors . Trazodone and m-CPP in plasma were extracted by a rapid and simple p rocedure based on CN bonded-phase extraction, and C-8 reversed-phase H PLC separation. Determination was possible for trazodone in the concen tration range 100-2000 ng mL(-1) and for m-CPP in the concentration ra nge 5-100 ng mL(-1). The recoveries of trazodone and m-CPP added to pl asma were 81.0-84.2 and 68.0-73.2%, respectively, with coefficients of variation of less than 7.3 and 8.2%, respectively. The method is appl icable to high level monitoring of trazodone and low level monitoring of m-CPP in plasma of healthy volunteers and patients treated with tra zodone.