Abstract: A high performance liquid chromatography-photodiode array detector for determining the content of melamine in fresh milk and dairy produce was studied. Referring to FDA method and NY/T 1372—2007 of determination melamine,the chromatogram conditions for determining the content of melamine were discussed and the predisposal method of melamine in fresh milk and dairy product was optimized. The optimal detection conditions are determined as follows: 0. 02mol/L ammonium sulfate-methanol (94: 6,V/V) as mobile phase,and detection wavelength 203 nm. The good linearity is in the range of from 0.1 to 150 μg/ml,the detection limit is 0.5 mg/kg,the average recoveries of melamine are above 91%,and the regression equation is y=2.37×105x+1.21×104 with the coefficient 0.9998. The method is simple,rapid,sensitive and exact with convenient sample treatment method feasible. It is suitable for the determination of melamine in fresh milk and dairy product.

Key words: high performance liquid chromatography, photodiode array detector, fresh milk, dairy product, melamine