Acta Pharm. 52 (2002) 289-297
A simple, rapid and selective method for the extractive spectrophotometric determination of dibenzazepines, viz., imipramine hydrochloride (IPH), desipramine hydrochloride (DPH), clomipramine hydrochloride (CPH), trimipramine maleate (TPM) and opipramol (OPP) has been worked out using the acidic dye, thymol blue, as the ion-pairing agent in an aqueous medium (pH 7). The yellow ion-pair chromogen being extractable with chloroform could be measured quantitatively at 420 nm. The method obeys Beer's law between 4-44, 4-44, 4-26, 4-24 and 4-36 mg mL-1 with molar absorptivity of 3.88 x 103, 3.36 x 103 2.50 x 103, 3.30 x 103 and 3.63 x 103 L mol-1 cm-1 for IPH, DPH, CPH, TPM and OPP, respectively. The commonly encountered excipients and additives do not interfere with the determination. Dibenzazepine drugs (20.0 mg mL-1) can be determined with the relative standard deviation of 1.2 to 2.8% (n = 5). Analyses of preformulations and commercial tablets carried out by this procedure agreed well with the results of the official method.
Keywords: extractive spectrophotometry, tricyclic antidepressant, dibenzazepine, thymol blue