Determination of melamine in milk powder by high performance liquid chromatography after matrix solid phase dispersion extraction

Objective:To establish a method for rapid determination of melamine in milk powder by high performance liquid chromatography after matrix solid phase dispersion extraction.Methods: TritonX-100 and trichloroacetic acid were used for demulsification of samples,and after centrifugation,the supernatant was cleaned up by solid phase extraction using PSA and C18(4∶ 1,m/m) as dispersants,which was analyzed by Waters XBridge C18 column with volume ratio acetonitrile and sodium octane(pH=3) of 10∶ 90(V/V) and detected by ultraviolet detector.Results: The pretreatment method of sample and the chromatographic conditions of analysis were critically optimized and the results showed good linearities in the ranges from 1.00 μg/ml to 100.0 μg/ml with correlation coefficients(r) no less than 0.9991.The detection limit of the method was 0.5 mg/kg.The relative standard deviations(RSDs) were 1.2%~2.9%,and the recoveries were 90.5%~99.1%.Conclusion: The method has advantages of simplicity,high sensitivity and less pollutants,and could be widely used for analyzing the melamine in many kinds of milk products.