Laboratory Information Bulletin LIB No. 4396 Volume 23, May 2007Determination of Melamine Residues in Catfish Tissue by Triple Quadrupole LC-MS-MS with HILIC ChromatographyWendy C. Andersen, Sherri B. Turnipseed, Christine M. Karbiwnyk, and Mark R. MadsonU.S. Food and Drug Administration, Animal Drugs Research Center, Denver, CO ABSTRACTA triple quadrupole liquid chromatography tandem mass spectrometry method is presented for the quantitative determination and confirmation of melamine residues in catfish. Catfish tissue was extracted with 50:50 acetonitrile:water and 1 N hydrochloric acid and cleaned-up using Oasis® MCX solid phase extraction cartridges. Extracts were analyzed by LC-MS-MS with HILIC chromatography and electrospray ionization in positive ion mode. The precursor ion for melamine is m/z 127. Two product ion transitions were monitored at m/z 85 and 68 for quantification and confirmation. Catfish tissue was fortified at 10, 25, 50, 100, and 500 ng/g (ppb). The average recovery of melamine from fortified samples (n = 17) was 76.3 % with an RSD of 14.3 %.