直接提取进样石墨炉原子吸收法测定大米中的镉含量

Determination of cadmium content in rice by direct dilution injection graphite furnace atomic absorption spectrometry

建立直接提取进样石墨炉原子吸收仪测定大米中镉含量的分析方法。将粉碎的大米用0.5%硝酸+0.1%曲拉通混合液提取、稀释定容,摇匀待测。以NH_4H_2PO_4+Mg(NO_3)_2为基体改进剂,用塞曼效应扣背景的方式,分别采用一步灰化(氩气)、两步灰化(氩气+空气)标准曲线法和标准加入法测定大米中的镉含量。结果表明三种方法测试样品的RSD(N=6)值分别为1.78%、3.29%、0.62%,加标回收率分别为114.7%、103.9%、102.5%,检出限分别为0.025、0.031、0.035μg/L。经t检验,两两比较,两步灰化和标准加入法无显著性差异,且精密度和准确度都能够满足要求。直接稀释进样测定大米中镉含量的方法操作简便,分析速度快,无污染,灵敏度高且准确性好。

Objective:To establish the method of determination of cadmium in rice by direct dilution injec-tion graphite furnace atomic absorption spectrometry.Methods:Crushed rice was diluted by mixture of 0.5% nitric acid and 0.1% Triton.Then the diluent was well shaken for further test.NH4 H2 PO4 +Mg (NO3 )2 were chosen as the matrix modifier,while the Zeeman effect background deduction method was a-dopted.The samples were subjected to one -step ashing method(argon),and two -step ashing method (argon +air),respectively,to create external standard calibration curves.The standard addition method was used to determine cadmium content in rice.The results showed that the RSD(N =6)of three methods were 1.78%,3.29%,and 0.62%,while the recovery rates were 114.7%,103.9%,and 102.5%.The detection limits were 0.025,0.031,and 0.035 μg/L.After T test of pairwise comparison,no significant difference was shown between two -step ashing method and standard addition method,and the accuracy and precision meet the requirements for determination well.Conclusion:As a simple,rapid and non -pol-luting method,the direct dilution injection graphite furnace atomic absorption spectrometry can be used for the determination of cadmium content in rice precisely and accurately.