Determination of Residual Amount of Melamine in Foodstuffs by Hyphenation of Liquid Chromatography and Mass Spectrometry in Tandem

It was reported that residual amount of melamine in foodstuffs of animal origin was determined by LC-MS/MS. Melamine was separated from the sample,in which standard melamine labelled with 15N3 was added as internal standard,by extraction with acetonitrile and partitioned with saturated sodium chloride solution. After centrifugation,an aliquot of the supernatant was taken for separation by reverse phase liquid chromatography and the content of melamine was determined by MS/MS. Lower limit of determination (10S/N) of the method was found to be 0.05 mg·kg-1. Tests for recovery were made by addition of standard melamine at 4 different concentration levels to 5 kinds of foodstuffs as matrixes,values of recovery found were in the range of 72.9%-104.1%,with values of RSD′s (n=6) in the range from 4.7% to 15.2%.