Determination of mesalazine [5-aminosalicylic acid] Tablets and in presence of its related compounds by derivative and difference spectrophotometry and by synchronous spectrophotometry

Spectrophotometric and spectrofluorimetric methods were presented for analysis of mesalazine [5-aminosalicylic acid], [5-ASA], in tablet form and in the presence of its related compounds, i.e. 4-aminosalicylic acid [4-ASA] and salicylic acid [SA], as impurities in raw materials. The spectrophotometric method applied the spectrophotometric technique [delta A-method] and first derivative technique [D1-method]. The second method involves a sensitive spectrofluorimetric method using the fluorescence characteristics of mesalazine in alkaline medium [10 -3 M NaOH]. The spectrofluorimetric method is 20 times more sensitive than the spectrophotometric one. Determination of 5-aminosalicylic acid in the presence of 4-aminosalicylic acid and salicylic acid was performed using D1-method, direct spectrofluorimetry and synchronous spectrofluorimetry

Second-derivative spectrophotometric determination of some weakly absorbing drugs in their formulations

A rapid and sensitive second-derivative spectrophotometric method was described for the estimation of some weakly absorbing drugs in their pharmaceutical dosage forms. The interference of the formulation excipients in conventional UV spectrophotometric methods is eliminated by the application of the proposed methods. Good linearity of D2 values versus concentration for different drugs permits their assay in tablets/vials with high accuracy and precision. The results of the proposed method are comparable with those of the official method and are more accurate than the conventional spectrophotometric method