Spectrophotometric determination of quetiapine fumarate through ion-pair complexation reaction with tropaeolin ooo

A sensitive, rapid and reproducible spectrophotometric method for the determination of quetiapine fumarate (QTF), an antipsychotic drug, in bulk drug, tablets and human urine has been developed and validated. The method includes the formation of a 1:2 chloroform extractable ion-pair complex between the drug and the dye tropaeolin ooo (TP) in acidic medium (pH 1.83+0.03). The resulting orange-red coloured ion-pair complex exhibits an absorption maximum at 480 nm. The optimum conditions for the ion-pair formation have also been established. The method permits the determination of QTF over a concentration range 2.0-20.0 mu g mL(-1). The apparent molar absorptivity and Sandell sensitivity values are found to be 2.30x10(4) Lmol(-1)cm(-1) and 0.0264 mu g cm(-2) respectively. The limits of quantitation and detection values are also reported. The accuracy and precision results of the method evaluated on intra-day and inter-day basis are found to be satisfactory. The proposed method has been successfully applied to the determination of QTF in bulk drug, tablets and spiked human urine with satisfactory results. The excipients from the tablets and other basic substances present in urine do not interfere in the assay.