Determination of Melamine Residue in Egg by HPLC-MS/MS

An high-performance liquid chromatographic method with tandem mass spectrometry(HPLC-MS/MS) was developed for the determination of melamine residues in egg. In the method, the melamine residue was extracted with V(1% Trichloroacetic acid):V(methanol)＝1:1, cleaned-up with PCX solid phase extraction column, and concentrated to dry under nitrogen and redissolved in 1 mL dissolving solution. The solution was separated on a RP-HPLC column, and detected by HPLC-MS/MS with positive electrospray ionization(ESI＋) in multiple reaction monitoring(MRM) mode. Quantitation was carried out using an external standard method. The standard curves for all compounds are linear over the concentration range of 20-400 μg kg^－1 with correlation coefficients(r2) of 0.998 5. The recoveries of melamine from egg samples spiked with the concentration levels at 50, 100, 200 μg kg^－1 are range of 87.0%, 96.8%, 94.4%. The limits of detection for the method are 3 μg kg^－1. The limits of quantification for the method are 10 μg kg^－1. The results show that the established method is of simplicity, rapidity, high sensitivity, good reproducibility and better selectivity. The method is quite fit for identification and determination of melamine in egg.