On the Digestion of Food and Biological Samples in the Determination of Micro-Amounts of Tin

In the determination of micro-amounts of tin in foodstuff and biological samples by HG-AFS,4 different methods (including the dry-ashing,acid digestion with HNO3-HClO4 and with HNO3-H2SO4-HClO4 as well as acid digestion with HNO3+H2O2 assisted with microwave heating) of sample digestion were tested,and the last 2 methods were found to be more satisfactory.The values of recovery and RSD′s (n=6) found for the two methods were in the ranges of 98.2%-101.4%,97.4%-102.8% and 2.39%-3.85%,3.25%-3.82% respectively.But if sulfate ion was to be avoided,the digestion with HNO3-H2O2 assisted with micro wave heating should be used.For determination of tin,linear relationship was kept up to 20.0 μg·L-1 with correlation coefficient of 0.999 8.