Analysis of trace elements in corncob by microwave digestion-ICP-AES

The contents of trace elements of Zn, Mg, Mn, Sr, Fe, Pb, Cu and Se in the corncob collected from Beijing, Shandong, Jilin, Yunnan, Xinjiang, Gansu, Shanxi, Shaanxi, Jiangsu, Neimeng in China were determined by ICP-AES using microwave digestion. The optimum condition of digesting the corncob was: Put 1.5 mL of 68% nitric acid and 0.5 mL of hydrofluoric acid in the pot, then digested the sample with 3 steps under the 400 W power in the microwave oven. This digesting procedure could completely and quickly digest the sample. The relative standard deviations and recovery yield are 0.72%-4.16% and 95.5%-104.5% for Zn, 1.58-3.66% and 98.2%-103.5% for Mg, 0.19%-4.58% and 97.0%-103.2% for Mn, 1.31%-4.90% and 95.7%-104.1% for Sr, 1.40%-4.01% and 95.9%-104.6% for Fe, 1.55%-4.28% and 95.1%-104.5% for Pb, 2.16%-5.00% and 96.4%-103.5% for Cu, and 2.00%-4.99% and 95.1%-101.3% for Se, respectively. The analysis of the trace metals by the method of ICP-AES using the method of microwave digestion proved to be easily operational, rapid, highly sensitive, and accurate. It could be adopted as the method of determining many elements simultaneously.