Determination of Melamine in Milk by Capillary Zone Electrophoresis After On-line Enrichment

A method for the determination of melamine in milk by capillary zone electrophoresis (CZE) with on-line enrichment was proposed.Through systematic study on the conditions of separation by CZE,optimum conditions were found as follows: ① concn.Of PBS: 20 mmol·L-1;② pH values of PBS: 3.0;③ moving voltage: 30 kV;④ wavelength of detection: 208 nm.Linear relationship between values of detection signal and concentration of melamine was obtained in the range of 0.83-106.70 mg·L-1.Detection limit (3S/N) found was 0.2 mg·L-1.Under the optimum condition,melamine was completely separated from the baseline within 8 min.Values of RSD′s of migration times and peak area were 0.72% and 1.02%,and as proved by the results obtained,the sample was stable within 8 h.