Rapid Determination of Melamine in Milk by High Performance Liquid Chromatography

An analytical method for rapid determination of melamine was developed by organic solvent extraction combination with ion-pair chromatography.The milk sample was extracted with organic solvents.The supernatant was analyzed by high-performance liquid chromatography(HPLC).The ion pair chromatographic separation was performed using a Welch Materials XB-C18 column(150 mm×4.6 mm,5 μm) with organic solvent added ion-pair reagent as the mobile phase.The extract got by separately using four organic solvents such as acetone,acetonitrile,ethanol and isopropyl alcohol was tested and compared in different mobile phase.The results showed that if appropriate mobile phase was chosen,the adoption of acetone,ethanol and isopropyl alcohol as organic agents for melamine extraction could also got good results.In mobile phase of methanol ion-pair reagent,a good linear relationship(r=0.999 98) between concentration and chromatographic peak area was obtained in the range of 1.0-100.0 mg/L.The detection limit(S/N=3) of melamine was 0.1 mg/kg.When acetone was used as extraction agent for melamine,the average recoveries were in the range of 97%-103% with relative standard deviations(RSD) less than 5%.This method was simple,rapid,accurate,and could meet the testing requirements.