High-Performance Liquid Chromatographic Method for the Determination of Cyromazine and Melamine Residues in Milk and Pork

A high-performance liquid chromatography method is described in this paper. The method uses NH2 column and 97% acetonitrile eluate to determine the insecticide cyromazine and metabolite melamine residues in milk and pork. Samples were treated with NaOH and extracted with acetonitrile containing 20% NH4OH. Target analytes of samples were cleaned up and concentrated by C-18 column solid-phase extraction. A separation for cyromazine and melamine was achieved, and respective retention times were 8 and 12 min. The calibration curves for cyromazine and melamine were linear in a concentration range of 0.01-1.0 mu g/mL, with correlation coefficients of 0.9999 and 0.9997, respectively. The limit of detection of both compounds was 0.2 ng, and the limit of quantitation was 0.02 mg/kg. Recoveries of cyromazine and melamine at fortified levels of 0.02, 0.05, and 0.1 mg/kg ranged from 84.5-90.8%, and 83.6-91.3%, respectively, with coefficient of variation of 3.1-7.8%.