Determination of Methylene Blue and Its Metabolites in Aquatic Products by High Performance Liquid Chromatography

An effective high performance liquid chromatographic method has been developed for the determination of dye methylene blue( M B) and its metabolites azure A ( AZA), azure B ( AZB), azure C ( AZC) in aquatic products, and applied to samples of incurred samples, which had been dosed with methylene blue. Based on ion-pair formation with p-toluenesulfonic acid, the analyles were extracted from homogenised tissue using acetonitrile, partitioned against methylene dichloride, and purified with a mixed-mode cation exchange solid phase extraction cartridges. The linear range was 0. 005 - 0. 50 mg/kg in spiked samples and the correlation coefficients were 0. 9946 - 0. 9978. The average recoveries and the relative standard deviation ranged from 75. 9% to 93. 2% and 3. 3% to 11. 9%, respectively, in spiked tissue samples at concentration levels ranging front 0. 005 to 0. 5 mg/kg of each analytes. The limits of detection( LOD) of AZA, AZB, AZC and MB were I. 27, 0. 98, 1. 48 and 1. 33 mu g/kg, respectively. This method is suitable for the determination of methylene blue and its metabolites residues in aquaetic products and pharmacokinetics study.