Two Microwave Digestion Pretreatment Methods for Determination of Heavy Metals in Vegetable Samples

Microwave digestion technology is a relatively recent method for processing biological samples, but there are some problems, such as low efficiency, which require further study. As described in this paper, vegetables were decomposed by two different microwave digestion methods of high pressure low flux and low pressure high flux microwave digestion. The contents of As, Cd, Cr, Cu, Ni, Pb and Zn in the sample solutions were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), and contents of Hg by Hydride Generation-Cold Atomic Fluorescence Spectrometry (HG-CAFS). As shown by the experimental results, the measured value of National Standard Reference Materials is in agreement with the certified values by the two different methods. The relative errors of the two methods were less than 21%, the relative standard deviation was less than 4% and the recovery ratios were 91.5%-103.8%. Low pressure high flux microwave digestion method is a better method of sample dissolution for large quantities of biological sample analysis because it improves the efficiency of sample digestion.