Simple liquid chromatographic method for the analysis of 5-aminosalicylic acid and its degradation product

5-Aminosalicylic acid (5-ASA, mesalamine) is an antiinflammatory agent used in the treatment of Crohn's disease and ulcerative colitis. A simple LC method was developed and validated for the analysis of 5-ASA. The chromatographic separation was achieved on a reversed-phase, C₈ column with UV detection at 290 nm. This isocratic system was operated at ambient temperature and required 8 min of chromatographic time. The mobile phase consisted of methanol;phosphate buffer pH 7.4 (20:80, v/v). The flow-rate was maintained at 1.0 ml/min. Standard curves were linear over the concentration range of 10 to 200 μg ml^-1. Intra-day and inter-day relative standard deviations ranged from 1.1-3.5% and 1.2-4.6% respectively. This method was used to: (1) quantify 5-ASA in pharmaceutical formulations without any complex sample extraction procedure, and (2) study the stability of 5-ASA in Sorensen's phosphate buffer (pH 7.4), Sorensen's phosphate buffer containing 5 mg% (w/v) of Carbopol, and in pharmaceutical formulations.