Microwave Digestion-Graphite Furnace Atomic Absorption Spectrometry for the Determination of Lead and Cadmium in Foods

Objective To investigate the microwave digestion-graphite furnace atomic absorption spectrometry for the determination of lead and cadmium in contaminated foods.Method Using microwave digestion technique,under the conditions of step elevating temperature and heating power,food samples were decomposed completely by nitric acid and hydrogen peroxide;then the lead and cadmium were determined by graphite furnace atomic absorption spectrometry.Results There is a good linear relationship at the concentration of 0-20.0 μg /L for lead and at 0-10.0 μg /L for cadmium;the correlation coefficient of lead is 0.999 5 and that of cadmium is 0.999 7;the detection limit is 5.0 μg /kg for lead and is 0.10 μg /kg for cadmium;The relative standard deviation for lead is less than 5.4%,and that for cadmium is less than 7.8%;the recovery for lead is 90.0%-105.0%,and that for cadmium is 90.0%-105.0%.The pass rates for lead in 240 food samples in four categories,including rice (flour),liver (pig kidney),aquatic products and dried mushroom,were 86.5%,77.5%,81.5% and 87.5%,respectively;and that for cadmium were 82.0%,76.5%,90.0% and 88.0%,respectively.Conclusion The method can meet the requirements for the analysis of lead and cadmium in contaminated foods.