Abstract:This article aimed to compare the effects of microwave digestion and wet digestion on the determination of lead（Pb），arsenic（As），cadmium（Cd），and chromium（Cr）in wheat flour by inductively coupled plasma-mass spectrometry（ICP-MS）.Appropriate amount of sample was made into in three concentration gradients with six parallels for each gradient.Then，samples were treated by microwave digestion and wet digestion，respectively，and diluted to the scale with deionized water.The content of Pb，As，Cd and Cr in samples was determined by ICP-MS with external standard method，and the internal standard indium （In）was used for on-line calibration.The interferences in MS were eliminated by kinetic energy discrimination（KED）and finally standard sample was used for verification.The digestion time and reagent consumption of the two preprocessing methods were compared.The analysis indicated that the four elements showed good linearity in the range of 0-100 μg/L.The correlation coefficients were all over 0.999 5 and the detection limits were 0.010 μg/L-0.117 μg/L.The recoveries were 80.3%-104.4% and relative standard deviation （n=6）were 1.71%-8.65%.Microwave digestion took 2.55 h with 5 mL nitric acid and 2 mL hydrogen peroxide，and wet digestion cost about 7.03 h with 20.5 mL nitric acid and 2 mL perchloric acid.