Application of Chloranil and Fluoranil π-Acceptors for the Spectrophotometric Determination of Mesalamine in Pharmaceutical Bulk and Dosage Forms

摘要

Two simple, sensitive and accurate spectrophotometric methods for the determination of mesalamine are described. The methods are based on charge-transfer complex formation reactions of the drug with two π -electron acceptors, p -chloranil and p -fluoranil, in aqueous medium. The coloured complexes having maximum absorbance at 346 nm and 347 nm by using p -chloranil and p -fluoranil reagents respectively. Under the optimized experimental conditions, the calibration curves showed a linear relationship over the concentration ranges of 1–35 and 1-30 μgml ? 1 with molar absorptivity values 4.60×10 3 and 5.67×10 3 L. mol -1 .cm -1 . using above reagents respectively. The limits of detection and quantitation were found 0.376 and 1.25 μgml ? 1 using p- chloranil, respectively, and 0.333 and 1.111 μgml ? 1 using p- fluoranil, respectively. The complexes were found to be formed in ratio of 1:1 species in both methods, with stability constants of 6.9′10 4 and 5.1′10 5 L.mol -1 for mesalamine complexes with p -chloranil and p -fluoranil respectively. The methods were applied successfully to the assay of mesalamine in pharmaceutical formulations and was agreed well with its certified value.