Determination of cyromazine and melamine in chicken eggs using quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction coupled with liquid chromatography-tandem mass spectrometry.

A rapid and sensitive method has been developed for the simultaneous detection of cyromazine and melamine in chicken eggs using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The optimal extraction solvent for the liquid-liquid extraction was 5 mL of acetonitrile with a 0.1 M hydrochloric acid aqueous solution (99.5:0.5, v/v). The extract was cleaned with 0.5 g of anhydrous magnesium sulfate and 10 mg of graphitized carbon black. The analysis of cyromazine and melamine was accomplished by combining the use of an anion exchange LC column with tandem mass spectrometry in the positive electrospray ionization mode with selected reaction monitoring mode (SRM). The detection limits were 1.6 ng g(-1) for cyromazine and 8 ng g(-1) for melamine, and the quantitation limits were 5.5 ng g(-1) for cyromazine and 25 ng g(-1) for melamine. The recoveries of cyromazine and melamine in the spiked egg samples were 83.2% and 104.6%, respectively, with an relative standard deviation (RSD) of less than 18.1%. The intra-day and inter-day precisions, represented by the RSD, ranged from 1.5% to 8.8% and 6.8% to 14.3%, respectively. The proposed method was tested by analyzing chicken eggs from the markets and from the veterinary medicine laboratory. The concentrations of cyromazine and melamine detected in these samples were in the range of 20-94 ng g(-1). The results demonstrated that the QuEChERS method combined with LC-MS/MS is a simple, rapid and inexpensive method for the analysis of cyromazine and melamine in eggs.