Rapid and High-Throughput Determination of Melamine in Milk Products and Eggs by Full Automatic On-line Polymer Monolith Microextraction Coupled to High-Performance Liquid Chromatography

A rapid and high-throughput method for monitoring melamine (MEL) in milk products and eggs was presented. This method was based on a full automatic platform that was composed of on-line polymer monolith microextraction and high-performance liquid chromatography with ultraviolet detection. A poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-ethylene dimethacrylate) monolith was selected as the sorbent for purification and enrichment of MEL in milk products and eggs. A novel mixed-mode chromatographic column packed with octyl and sulfonic acid co-bonded silica was employed for quantitative determination of MEL in real samples. Several factors affecting extraction performance were investigated. Under the optimal conditions, the recoveries of MEL in milk products and eggs spiked at three levels of 0.5, 5.0, and 20.0 mg/Kg, ranged from 87.0% to 95.5%, with RSDs less than 6.4%. The limits of detection were 0.024 and 0.018 mg/Kg for MEL in the milk products and eggs, respectively.