Two simple and sensitive spectrophotometric methods for the determination of seven CNS
acting drugs namely; haloperidol, droperidol, chlorpromazine hydrochloride, thioridazine
hydrochloride, imipramine hydrochloride, desipramine hydrochloride and clomipramine
hydrochloride are presented. The first method is based on formation of an ion-pair complex
between each of studied drugs and oxidized quercetin at pH range from 4.5 to 5.0. The colored
complex formed was quantitatively extracted into dichloroethane, filtered over anhydrous
sodium sulphate and then measured in the range of 528-534 nm. Beer's law was obeyed for all
the studied drugs in the concentration range of 2-45 μg/ml. The second method is a rapid
kinetic method based on in-situ oxidation of quercetin into a red colored compound measured
at 515 nm. The rate of reaction between each of studied drugs and oxidized quercetin was
followed by measuring the decrease in absorption intensity as a result of its reduction by each
of the studied drugs. The studied compounds were determined in the concentration range of 5-
50 μg/ml using slope, fixed time and variable time methods. The two methods were successfully
applied to the analysis of studied drugs in the pure form and in commercial pharmaceuticals.
The results were comparable with those obtained with either official or reported methods.