Determination of residues of cyromazine and its metabolite, melamine, in animal-derived food by gas chromatography-mass spectrometry with derivatization.

A gas chromatography-mass spectrometric (GC-MS) method was established for the determination of cyromazine and its metabolite, melamine, in animal-derived food. Chicken and tilapia muscle samples were spiked with (15)N(3)-melamine, extracted with an acidic acetonitrile/water solution, and defatted with dichloromethane. Egg and milk samples were directly extracted with 3% trichloroacetic acid. The extracts were purified using mixed cation-exchange cartridges, derived with N,O-bis(trimethylsilyl)trifluoroacetamide, and detected by GC-MS. Cyromazine and melamine were quantified by external standard methods except for the determination of melamine in animal muscle, which used an internal standard method. Recoveries ranged from 75.0 to 110.0%, and relative standard deviations were <15.0%. In animal muscle the limits of quantification (LOQs) were 20 microg/kg and the limits of detection (LODs) were 10 microg/kg for cyromazine and melamine. In milk and eggs the LOQs were 10 microg/kg and the LODs were 5 microg/kg for both analytes.