Determination of Micro-amount of Elements in Plant Samples by Inductively Coupled Plasma-Mass Spectrometry with Microwave Digestion

The plant samples were decomposed by microwave digestion using H2O2-HNO3as solvent. The external standard method was used for calibration. 11 micro-amount of elements of B, Cd, Cu, Co, Cr, Mo, Li, Ni, Pb, La and Ge in the plant samples were determined simultaneously by inductively coupled plasmamass spectrometry (ICP-MS). The parameters for microwave digestion and ICP-MS instrumental operation were optimized by experiments. The interference from organic residues and coexistent ions on determination of Pb, Cd, Ni and the interference eliminating methods were studied. 114Cd, 10B, 65Cu, 59Co, 52Cr, 98Mo, 7Li, 60Ni, 208Pb, 139La and 74Ge were chosen as determining isotopes and 103Rh and 45Sc were chosen as internal standards. The detection limits (10SD） of method for 11 elements were in a range of 5 ng/g to 150 ng/g. The method has been validated by determination of these elements in National Standard Reference materials and the results are in agreement with certified values with precision of 1.27％ to 5.27％RSD (n=12). The method is suitable for determining these microamount of elements in fruits, roots, stems and leaves of different plants.