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 forthe determination of bisacodyl in pure form and in some of its pharmaceuticalpreparations.Method: The method is based on the oxidation of bisacodyl by iron (III), andsubsequent complexation of iron (II) with o-phenanthroline.Results: Forming a red-colored complex (ferroin) having the maximum absorbance at510 nm. Beers law is obeyed in the concentration range of 0.5-5 g/ml. The molarabsorptivity and sandells sensitivity were 1.55104 L.mol-1.cm-1 and 0.0233g.cm-2respectively. The relative standard deviation (RSD) was less than 1.5 (n=11). Thelimits of detection and quantitation are 0.083 and 0.25 g.ml-1 respectively.Conclusion: The method is applied successfully for determination of bisacodyl inenvironmental water samples and in some pharmaceutical formulations (tablets andsuppositories). A statistical comparison of these results with those of official methodshows good agreement and indicates no significant difference in the precision.