Method Comparison to Determination of As, Cd, Hg and Pb in Food by ICPMS, AFS, GF-AAS

As、Cd、Hg、Pb were detected by ICP-MS，and then As、 Hg were detected by AFS, Cd、 Pb were detected by AAS respectively. The comparison of 3 methods was studied. Microwave-digestion and wet digestion was adopted as pre-digestion method in ICP-MS and AFS， GF-AAS. By improving conditions of degistion, choosing internal elements and EPA200.8 interference calibration equation, using thiourea-ascorbic acid as masking agent and HNO₃-Pd(HNO₃)₂ as amelioration agent, using CRM wheat flour（GBW08503b） and rice flour （GBW10010）, the accuracy and reliability of the method was verified. Determination results of elements are in the range which is permitted.The relative deviation of food samples is less than 20%. ICP-MS method has wide dynamic range, do not have to dilute the sample, it is suitable for a lot of samples and multi-element analysis at the same time,but it is expensive and relatively high cost. The measurement of the element by AFS and GF-AAS is one by one to ensure that the results are accurate and reliable, but because of the narrow linear range some samples have to be diluted,they have longer determination period and wide popularity.