Determination of Methylene Blue and Its Metabolite Residues in Aquatic Products by High-Performance Liquid Chromatography-Tandem Mass Spectrometry

A sensitive and reliable method was developed to determine methylene blue (MB) and its metabolite residues, including azure A (AZA), azure B (AZB), and azure C (AZC) in aquatic products by HPLC-MS/MS. The samples were extracted by acetonitrile and cleaned up by alumina-neutral (ALN) cartridges. The analytes were separated on a Sunfire C18 column (150 mm x 2.1 mm, 5 mu m). The method was validated according to the European criteria of Commission Decision 2002/657/CE. Good linearity between 1-500 mu g/L was obtained with correlation coefficients (R-2) greater than 0.99. The limit of quantification (LOQ) was 1.0 mu g/kg. The average recoveries at three levels of each compound (1, 5, and 10 mu g/kg) were demonstrated to be in the range of 71.8-97.5%, with relative standard deviations (RSDs) from 1.05% to 8.63%. This method was suitable for the detection of methylene blue and its metabolite residues in aquatic products.

Automated summary

A sensitive and reliable HPLC-MS/MS method was developed for the determination of methylene blue and its metabolite residues in aquatic products. The method showed good linearity, met European criteria, and was suitable for the detection of methylene blue and its metabolite residues in aquatic products.