Abstract: A high performance capillary electrophoresis (HPCE) method has been established for the separation of melamine in milk and milk powder. The separation was carried out on a fused-silica uncoated capillary column （58.5 cm×75 μm）. The sample was injected by hydrodynamic injection (3.5 kPa (35 mbar)×8 s) at a temperature of 25 ℃. The analysis was completed in about 6 min in 40 mmol/L Na2HPO4-20 mmol/L citric acid buffer (pH 2.6) at 25 kV of separation voltage and 232 nm of detection wavelength. The linear range of melamine was 1-100 mg/kg, and the correlation coefficient was higher than 0.997. The limits of quantification (LOQs) in milk and milk powder were 0.5 mg/kg and 1.0 mg/kg, respectively. The average recoveries were in the range of 72.2%-97.3% in the spiked range of the concentration of LOQs and 50 mg/kg, and the relative standard deviations were between 2.1% and 3.9%.

Key words: melamine, milk, milk powder , high performance capillary electrophoresis (HPCE)