High-performance liquid chromatographic assay of 5-aminosalicylic acid (5-ASA) and its metabolites N-beta-D-glucopyranosyl-5-ASA, N-acetyl-5-ASA, N-formyl-5-ASA and N-butyryl-5-ASA in biological fluids.

A fast, highly sensitive high-performance liquid chromatographic method for the simultaneous determination of 5-aminosalicylic acid (5-ASA) and its metabolites N-beta-D-glucopyranosyl-5-ASA, N-formyl-5-ASA, N-acetyl-5-ASA and N-butyryl-5-ASA has been developed using a dynamically modified silica approach on a 40 mm x 4.6 mm I.D. column packed with 3-microns Hypersil. Plasma proteins are precipitated with acetonitrile. After extraction of the acetonitrile into 1,1,1-trichloroethane an undiluted aqueous phase containing the analytes is obtained. The detection limits are in the range 0.002-0.05 microgram/ml in plasma at a signal-to-noise ratio of 3 using fluorescence detection.