[Analysis of 27 mineral elements in the rice samples collected from China and Japan by using ICP-OES and ICP-MS]

Based on microwave-assisted decomposition and dry ashing methods, the concentrations of Al, As, B, Ba, Ca, Cd, Co, Cr, Cs, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Se, Sr, T1, V and Zn in sixteen Chinese rice samples and eleven Japanese rice samples were analysed by using ICP-OES and ICP-MS, and a biological standard reference material rice (GBW10010) was used to verify the accuracy and the precision of analytical method. It was demonstrated that ICP-MS equipped with a collision cell technique can be successfully used for reducing polyatomic interferences in the detection of elements with low m/z ratios. Compared with those in Japanese rice samples, the concentrations of Al, S and Sr in Chinese rice samples are significantly high, and the concentrations of B, Cd, Cs, Mg, Mo, P, Pb and Zn in Chinese rice samples are much lower (P < 0.05). The Ward's method of cluster analysis applied to the concentrations of 26 elements except T1 whose concentration is below the detection limit exhibited the ability to effectively differentiate Chinese rice samples from Japanese rice samples. Moreover, it was found that the concentrations of magnesium correlate very well with the concentrations of phosphorus in all rice samples, with the correlation coefficient being as high as 0.9552.