X射线荧光光谱法快速测定小麦(粉)中镉含量

    Rapid determination of cadmium content in wheat (flour) by X-ray fluorescent spectrometry

    • 摘要: 为满足日常的食品风险监测和基层粮库现场收粮的检测需求,建立一种简单、快捷、准确、可靠的测定小麦(粉)中镉含量的分析方法。通过6个不同型号X射线荧光光谱仪测定小麦(粉)中镉含量,分别验证评价了方法的检出限、定量限、准确度以及精密度。结果表明,该方法的检出限为0.0219~0.0340 mg/kg,定量限为0.0303~0.0686 mg/kg,能够满足方法标准要求;该方法与石墨炉原子吸收光谱测定法采用配对t-检验,两种方法测定结果不存在显著性差异;通过12家实验室间验证分析,当小麦(粉)镉含量在0.054~0.414 mg/kg时,建立方法重复性标准差(Sr)和再现性标准差(SR)与镉含量(m)的关系式,得出测量方法精密度(以mg/kg表示)最终值关系式:Sr=0.031m+0.002;SR=0.026m+0.003,均符合相关数理统计要求。因此,该方法工艺参数合理,检测时间短,检测效率高,样品预处理简单,无试剂消耗,检测成本低,绿色环保,能满足目前检测应用需求,可广泛推广用于小麦(粉)中镉含量的快速检测。

       

      Abstract: Cadmium is a heavy metal environmental pollutant, and excessive intake of cadmium will endanger human health. National standard detection method for cadmium in wheat is stable, reliable and sensitive, but the sample pretreatment operation is complicated, the cycle is long, and it is restricted by equipment, personnel and environment, so it is not suitable for grass-roots personnel to master and promote. Therefore, in order to meet the needs of daily food risk monitoring and on-site grain collection detection in basic grain depots, a simple, fast, accurate and reliable analysis method for the determination of cadmium content in wheat (flour) was established. The limits of detection and quantification of cadmium in blank samples were determined by six different types of X-ray fluorescent spectrometer. In order to verify and evaluate the accuracy and precision of the method, AAS and XRF were used to detect 4 groups of positive wheat (flour) samples from 12 laboratories. The results showed that the limits of detection and quantification were 0.0219-0.0340 mg/kg and 0.0303-0.0686 mg/kg, which could meet the standard requirements of the method. Paired t-test was used for this method and GFAAS, and there was no significant difference between the two methods. Through verification and analysis among 12 laboratories, when the cadmium content of wheat (flour) was 0.054-0.414 mg/kg, the relationship between the method repeatability standard deviation Sr and reproducibility standard deviation SR and cadmium content m was established, and the final value of the precision of the measurement method (expressed in mg/kg) was: standard deviation of repeatability Sr = 0.031m+ 0.002 and the standard deviation of reproducibility SR = 0.026m+ 0.003, all in line with relevant mathematical statistics requirements. Therefore, the process and parameters of this method are reasonable, the detection time is short, the detection efficiency is high, the sample pretreatment is simple, no reagent consumption, the detection cost is low, and the method is green and environmentally friendly, which can meet the current detection application requirements and can be widely promoted for the rapid detection of cadmium content in wheat (flour).

       

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