Spectrophotometric Methods for Determination of Olsalazine Sodium

Three simple, sensitive, selective and accurate spectroscopic methods (A, B and C) have been developed for quantitative estimation of olsalazine sodium in bulk drug and pharmaceutical formulation (capsules). Method A and B is based on the reduction of ferric ions to ferrous ion by olsalazine sodium, which further in presence of 1,10-Phenanthroline, 2, 2′-Bipyridyl produce blood red coloured chromogen with absorption maximum at 510 nm and 518 nm respectively. Method C is based on the direct colorimetric measurements of olsalazine sodium with 0.1N Sodium hydroxide. It gives yellowish-orange coloured chromogen with absorption maximum at 465nm. Method A, B and C obey Beer's law in concentration range of 1–5 μg/ml, 5–25 μg/ml and 1–5 μg/ml respectively. Interference studies were conducted and it was found that the common excipients usually present in the dosage forms do not interfere in the proposed methods. The optical characteristics, regression analysis data, and precision of the methods were calculated. The proposed methods were found to be accurate, reproducible and consistent. It was successfully applied for the analysis of marketed formulation and could be effectively used for the routine analysis of formulations.