大米中重金属镉检测的质量控制因素探讨

Study on quality control of determination of heavy metal cadmium in rice

在同一实验室条件下,通过15名检测人员对大米中镉的检测全过程进行人员比对,评价了本实验室在该检测项目的内部质量控制。建立微波消解-原子吸收法测定镉的含量,在0.80~4.00 ng/ml的范围内线性关系良好,相关系数均大于0.997,检出限均小于0.002 3 mg/kg;在0.20、0.40、0.80 mg/kg加标水平下,3个浓度水平加标回收率为95.3%~101.5%,3次重复测定的相对标准偏差均小于等于5.4%;从15名人员检验数据结果可知,双试验相对标准偏差(RSD)均小于等于6.4%,z比分数评价全部小于等于1,表明“优秀”。人员比对实验能较好的判定检验人员的检测操作能力与水平,也能加强实验室对检测结果的质量控制,所以应定期进行人员比对实验,为大米中重金属镉的日常检测和质量控制提供参考和依据。

Under the same laboratory conditions, the internal quality control of the whole process of cadmium detection in rice was evaluated by 15 examiners.A microwave digestion-atomic absorption method was established to determine the content of cadmium.The linear relationship was good in the range of 0.80-4.00 ng/ml, the correlation coefficients were all greater than 0.997 and the detection limits were all less than 0.0023 mg/kg.At the spiked levels of 0.20,0.40 and 0.80 mg/kg, the recoveries of the three spiked levels were 95.3%-101.5%,and the relative standard deviations of the three repeats were all less than or equal to 5.4%.According to the data of 15 researchers, the relative standard deviations(RSD) of both experiments were less than or equal to 6.4%.All the Z-score evaluations were less than or equal to 1,indicating "excellent".Personnel comparison experiment could better judge the testing operation ability and level of inspectors, and strengthen the quality control of laboratory testing results.Therefore, personnel comparison experiment should be carried out regularly to provide reference and basis for the daily detection and quality control of heavy metal cadmium in rice.