Abstract: The cis-isomer of clopenthixol (I; zuclopenthixol) and its main dealkyl metabolite (II) were extracted from plasma and urine by adsorption on to a Bond-Elut CN cartridge and eluted therefrom with acetonitrile/butylamine (9:1). Analysis was by HPLC on a Spherisorb S5 CN column (12 cm x 4.6 mm i.d.), operated at 40°C with 6 mM dodecyltrimethylammonium bromide in H2O/acetonitrile/0.2 M phosphate buffer of pH 6.5 (59:36:5) as mobile phase. Eluate was fed through a PTFE photochemical reactor coil (5 m x 0.5 mm i.d.) irradiated by a low-pressure 8 W mercury UV lamp and fluorimetric detection at 435 nm (excitation at 260 nm). The calibration graph was linear from 0.1-50 ng of I injected. Recoveries of 0.1-50 ng/ml of I and II were 62-79% and 82-89%, respectively and corresponding RSD (n = 6) were 7.2-16.6% and 5.8-12.5%. The limit of detection was 6 pg of I.