[Determination of cyanuric acid in milk and milk powder by ultra performance liquid chromatography-tandem mass spectrometry with post-column ammoniation].

A method for the determination of cyanuric acid in milk and milk powder has been developed by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with post-column ammoniation. After extracted by 5% trichloroacetic acid, the samples were loaded onto an Acquity UPLC HSS T3 column (50 mm x 2.1 mm, 1.8 microm) and separated with a gradient elution. The electrospray was operated in the negative mode and monitored by the multiple reaction monitoring (MRM) mode. The calibration curves showed a good linearity in the range of 10.0-160.0 microg/L, and the correlation coefficients (r) were higher than 0.99. When the spiked levels were 0.05, 0.10, and 0.20 mg/kg, the recoveries of cyanuric acid in milk ranged from 60% to 118.5%, with the relative standard deviations (RSDs) of 8.2%-12.6%; while the spiked levels were 0.25, 0.50, and 1.00 mg/kg in the milk powder, the recoveries ranged from 88% to 108% and the RSDs ranged from 2.5%-5.7%. The limits of quantification (LOQs, S/N = 10) of cyanuric acid were 0.05 mg/kg in milk sample and 0.25 mg/kg in milk powder. The results indicate that the method is simple, rapid, sensitive and suitable for the qualitative and quantitative analyses of cyanuric acid in milk and milk powder samples.