Simultaneous determination of melamine and cyanuric acid in the urine by LC-APCI-MS/MS

Objective:To establish a liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometric method(LC-APCI-MS/MS) for the determination of melamine and cyanuric acid in urine samples.Methods: Urine samples were mixed with isotopic labeled internal standards,15N3-melamine and 13C3-cyanuric acid,and diluted with acetonitrile.After centrifugation and separated on a Waters XBridgeTM Amide column,the analytes were detected by APCI-MS/MS with the multiple reaction monitoring(MRM) mode,positive for melamine and negative for cyanuric acid.Results: Calibration curves were linear in the range of 20 ng/ml～1000 ng/ml for melamine and cyanuric acid,both with the correlation coefficient better than 0.995.The intra and inter-batch precision(RSD) both less than 10%,and the accuracies and recoveries were both in the range of 89.9%～111.2%.Conclusion: The method is simple,sensitive and specific for the quantitative determination of melamine and cyanuric acid in the urine.