On-line Preconcentration and Sensitive Determination of Melamine in Milk Powder and Animal Feeds Samples by Micellar Electrokinetic Chromatography

A sensitive analytical method using rnicellar electrokinetic chromatography with on-line preconcentration technique was developed for rapid determination of melamine in various samples. Two online preconcentration techniques including field-amplified sample stacking and sweeping micellar electrokinetic chromatographic technique (FASS- sweep MEKC) were used. The samples were extracted by acetonitrile for three times. Under the optimum conditions, the sensitivity was improved about 1000 times. The LODs was decreased from 2.0 mg/L to 1.8 mu g/L. The RSD were less than 4.5%. The recoveries were range in 97.2%-105%. This method is sensitive, reliable, economic and pretreatment-free for complex samples and can be easily used for product quality control of milk powder and animal feeds.