Microwave Digestion-FAAS Determination of Trace Elements in Five Kinds of Nuts

With microwave digestion,the five trace elements of Mg,Ca,Zn,Mn,Fe were determined by using flame atomic absorption spectrometry(FAAS) in the five samples which included peanut,walnut,hazelnut,chestnut and almond.The optimum conditions of microwave digestion was expounded,and the results showed that the digesting solution system for V(HNO3)+V(H2O2)=4+1 is the optimum choice and the best digestion effect will be achieved when the pressure and the time were 0.5 MPa and 60 s respectively in the first step of digestion,and 2.1 MPa and 300 s in the second step.The recovery of this method ranged from 97.30%~102.2%,and the relative standard deviation was less than 3.36%(n=5).The detection result of element content in nuts showed that five nuts are rich in trace elements,especially Mg and Ca,with Mg reaching about 2 000 μg/g,and Ca about 300 μg/g,followed by Fe,Zn,Mn etc..