Effects of Different Pretreatment Methods on the Determination of Major Heavy Metal Elements in Tropical Fruits by ICP-MS Method

Microwave digestion, wet digestion and dry digestion were used for the pretreatment of the fruit samples, and the best digestion method was established. Then, four elements including Pb, Cd, Cr and Ni in the samples with different pretreatment methods were detected and analyzed by using ICP-MS method. The results showed that the method detection limits of Pb, Cd, Cr and Ni after microwave digestion were respectively 0.029 0, 0.002 6, 0.021 0 and 0.250 0 μg·L^-1, and the relative standard deviations were all less than 2.5%, while the adding standard recovery was 88.1%-108.3%. The method detection limits of four elements after wet digestion were 0.028 0, 0.002 4, 0.018 0, 0.21 μg·L^-1, and the relative standard deviations were all less than 3.5%, while the adding standard recovery was 86.7%-106.9%. The method detection limits of four elements after dry digestion were 0.031 0、0.002 8、0.023 0、0.250 0 μg·L^-1, and the r relative standard deviations were all less than 3.5%, while the adding standard recovery was 86.6%-111.5%. By combining with ICP-MS method, the three pretreatment methods could all be used for the accurate detection of heavy metal elements in tropical fruits. Microwave digestion method had the advantages of accurate detection results, less time consumption and simple & convenient operation. Wet digestion method had the advantages of low method detection limits, accurate results and good reproducibility. Dry digestion method had the advantages of accurate results and more time consumption.