利用酸浸提-石墨炉原子吸收法测定大米中的镉

Determination of cadmium in rice by acid extraction graphite furnace atomic absorption spectrometry

为提高大米中重金属镉检测的精度,提出采用酸浸提结合石墨炉原子吸收法检测大米中的重金属镉。首先利用酸浸提对选取的大米样品进行预处理,然后采用石墨炉质谱仪对镉含量进行测定。结果表明,酸浸提的最佳工艺为:大米粉粒度0.18 mm,大米用量0.2 g,硝酸体积为1 ml,加热时间为20 min,浸提温度为60 o C,Triton X-100的质量分数为0.01%;在最佳浸提条件下,标准曲线的相关系数R 2为0.9957,检出限和定量限分别为0.003 mg/kg和0.009 mg/kg,相对标准偏差(RSD)为2.06%,标准样品标准值与测试均值偏差为-3.9%,符合国标GB/T 27404—2008和GB 5009.15—2014对相对标准偏差的要求,表现出良好的精密度和准确度。同时该方法与微波消解-ICP-MS测试的结果无显著差异,但样品预处理更为简单。

In order to improve the detection accuracy of cadmium in rice,acid extraction combined with graphite furnace atomic absorption spectrometry was proposed to detect the cadmium in rice.Firstly,the rice samples were pretreated by acid extraction,and then the cadmium content was determined by graphite furnace mass spectrometer.The results showed that the optimum conditions of acid extraction were as follows:grain size of rice 0.18 mm,rice dosage 0.2 g,nitric acid volume 1mL,heating time 20 min,extraction temperature 60℃,the mass fraction of Triton X-1000.01%;Under the optimum extraction and digestion conditions,the correlation coefficient of the standard curve was 0.9957,the detection limit and the quantification limit were 0.003 mg/kg and 0.009 mg/kg respectively,the relative standard deviation(RSD)was 2.06%,and the deviation between the true value of the sample and the test mean value was-3.09%,which conformed to the requirements of the national standards of GB/T 27404—2008 and GB 5009.15—2014 for the relative standard deviation,showing good precision and accuracy.At the same time,there was no significant difference between this method and microwave digestion ICP-MS test,but sample pretreatment was simpler.