Indirect spectrophotometric method for the determination of bisacodyl in commercial dosage forms and in environmental water samples

Objective: A simple, sensitive, and accurate indirect spectrophotometric method for the determination of bisacodyl in pure form and in some of its pharmaceutical preparations. Method: The method is based on the oxidation of bisacodyl by iron (III), and subsequent complexation of iron (II) with o-phenanthroline. Results: Forming a red-colored complex (ferroin) having the maximum absorbance at 510 nm. Beer’s law is obeyed in the concentration range of 0.5-5 µg/ml. The molar absorptivity and sandell’s sensitivity were 1.55×104 L.mol-1.cm-1 and 0.0233µg.cm-2 respectively. The relative standard deviation (RSD) was less than 1.5 (n=11). The limits of detection and quantitation are 0.083 and 0.25 µg.ml-1 respectively. Conclusion: The method is applied successfully for determination of bisacodyl in environmental water samples and in some pharmaceutical formulations (tablets and suppositories). A statistical comparison of these results with those of official method shows good agreement and indicates no significant difference in the precision.