UTILIZATION OF BROMINATION REACTION FOR THE SPECTROPHOTOMETRIC ASSAY

Three simple and sensitive spectrophotometric methods are described for the determination of domperidone (DOM) in bulk drug and in dosage forms using bromate-bromide mixture as brominating agent in acid medium and three dyes, meta-cresol purple (MCP), amaranth (AMR) and erioglaucine (EGC). The me-thods involve the addition of a known excess of bromate-bromide mixture to an acidified solution of DOM followed by the determination of the residual bromine by reacting with a fixed amount of either MCP dye and measuring the absor-bance at 530 nm (method A) or AMR dye and measuring the absorbance at 520 nm (method B) or EGC dye and measuring the absorbance at 630 nm (method C). Beer’s law is obeyed over the concentration ranges, 0.63–10.0, 0.25-4.0 and 0.13-2.0 µg mL-1 for method A, B and C, respectively. The ap-parent molar absorptivities are calculated to be 3.751×104, 6.604×104 and 1.987×105 L mol-1cm-1 for method A, B and C, respectively, and the corres-ponding sandell sensitivity values are 0.011, 0.006 and 0.002 μg cm-2. The limit of detection and the limit of quantification are also reported for all the three methods. No interference was observed from common additives found in phar-maceutical preparations. Statistical comparisons of the results with those of the reference method showed excellent agreement, and indicated no signifi-cant difference in accuracy and precision. The accuracy and reliability of the methods were further ascertained by performing recovery tests via standard--addition technique. Key words: domperidon; assay; spectrophotometry; bromate-bromide; dyes; tablets