取粉碎后的水稻样品约0.3 g,按设定的消解程序进行全自动石墨消解,消解完毕后,用5%(体积分数)硝酸溶液定容至25 mL,采用电感耦合等离子体质谱法测定其中铬、镉、砷、铝、锶、铅、钡、铊的含量,内标法定量。结果表明,铬、镉、砷、铝、锶、铅、钡、铊标准曲线的线性范围均为0.01~8.0 μg·L^-1,检出限(3S/N)分别为0.006,0.011,0.009,0.017,0.009,0.008,0.012,0.018 μg·kg^-1。按照标准加入法进行回收试验,回收率为83.9%~105%,测定值的相对标准偏差(n=6)均小于5.0%。方法用于实际大米样品的测定,其中铝和钡元素的检出率为100%,检出量分别为0.49~1.02 mg·kg^-1,0.019~0.071 mg·kg^-1;镉和铅元素的检出率为33%,检出量分别为0.028~0.042,0.025~0.074 mg·kg^-1;铬、砷、锶和铊均未检出。

The crushed rice sample (about 0.3 g) was taken and digested by automatic graphite digestion according to the setting digestion procedure. After digestion, its volume was made up to 25 mL with 5% (φ) nitric acid solution, and chromium, cadmium, arsenic, aluminum, strontium, lead, barium and thallium were determined in the above solution by inductively coupled plasma mass spectrometry. Internal standard method was used for quantitative analysis. As shown by the results, the linear ranges of standard curves of chromium, cadmium, arsenic, aluminum, strontium, lead, barium and thallium were all 0.01-8.0 μg·L^-1, with detection limits (3S/N) of 0.006, 0.011, 0.009, 0.017, 0.009, 0.008, 0.012, 0.018 μg·kg^-1, respectively. Recovery test was carried out by the standard addition method, giving results in the range of 83.9%-105%, with RSDs (n=6) of the determined values less than 5.0%. This method was applied to the determination of actual rice samples. The detection rates of aluminum and barium were 100%, with detection amounts of 0.49-1.02 mg·kg^-1 and 0.019-0.071 mg·kg^-1, respectively. The detection rates of cadmium and lead were 33%, with detection amounts of 0.028-0.042 mg·kg^-1 and 0.025-0.074 mg·kg^-1 respectively. Chromium, arsenic, strontium and thallium were not detected.