Abstract: Rice were grounded into rice powder by muller and soaked in mixed acid solution (concentrated nitric acid:concentrated sulphuric acid=3∶2) for 12 hours. Then, the mixture was heated slowly in a hood, and mixed acid solution and aqueous hydrogen peroxide solution were added for the digestion. In order to test the trace amount cadmium in rice with square wave stripping voltammetry method, a three-electrode system are used with the silver-based mercury film electrode as working electrode, platinum electrode as counter electrode, and saturated calomel electrode as reference electrode. The results show that a good linear relationship can be obtained in pH=3.0 NH4Cl（0.2 mol/L）substrate solution, within the concentration of cadmium 0.01~ 0.12 μg/mL; the regression equation was Ip=497.59c+15.324 with the correlation coefficient of 0.994 1, the detection limit of 4.607 4×10-3 μg/mL, the relative standard deviation of 4.12%~5.56%, and the recovery rate of 90.26%~98.16%.

Key words: Square wave stripping voltammetry , Rice , Cadmium

摘要： 　    将大米用粉碎机粉碎成米粉，用混合酸浸泡（Ｖ（浓硝酸）∶Ｖ（浓硫酸）＝３∶２）１２ｈ，在通风橱中缓慢加热，滴加混合酸及双氧水消解。以银基汞膜电极为工作电极，铂电极为对极，饱和甘汞电极为参比电极，利用方波阳极溶出伏安法测大米中的痕量镉。在ｐＨ＝３．０的０．２ｍｏｌ／Ｌ　ＮＨ４Ｃｌ底液中，峰电流与镉离子的质量浓度在０．０１～０．１２μｇ／ｍＬ内，峰电流与ρ（镉）呈良好的线性关系，线性回归方程为Ｉｐ＝４９７．５９ｃ＋１５．３２４，相关系数为０．９９４　１，检出限为４．６０７　４×１０^－３μｇ／ｍＬ，相对标准偏差为４．１２％～５．５６％，加标回收率为９０．２６％～９８．１６％。

关键词: 方波阳极溶出伏安法 , 　大米 , 　镉