能量色散X射线荧光光谱仪在稻米中镉含量测定的应用研究

Application of energy dispersive X-ray fluorescence spectrometer in determination of cadmium content in rice

中文关键词:  X射线荧光光谱仪  大米  镉  分析性能

英文关键词:X-ray fluorescence spectrometer  rice  cadmium  performance analysis

中文摘要:

      目的 研究能量色散X射线荧光光谱仪(X-ray fluorescence spectrometers, XRF)在稻米中镉元素快速测定中应用, 验证评价该仪器是否满足筛查稻米样品中镉含量的实际需求。方法 选择不同厂家典型X射线荧光光谱仪, 采用实际样品分别评估其定性和定量检出限, 批量样品评估检测效率以及定期稳定性等。考察稻米不同形态(糙米和精米)、测定时间和测定次数对X射线荧光光谱仪测定稻米中镉含量的影响, 同时比较不同品牌仪器间的差异性。结果 2台XRF仪器的筛查定量限均小于稻米中镉的限量值0.2 mg/kg。工作曲线线性关系(r2)大于0.99, 测量相对偏差小于20%, 150 d内定期稳定性监测的变异系数小于3%。单次测量时间小于20 min, 批量样品检测时间较长。结论 能量色散X射线荧光光谱仪灵敏度能够满足实际稻米样品中镉元素污染的快速筛查要求; 稻米的不同形态对X射线荧光光谱仪的检测结果无显著性影响; 随着测定时间和测定次数的增加, XRF方法的检测结果与实际量值更接近; 存在不同程度的假阴和假阳问题。

英文摘要:

      Objective To investigate the application of energy dispersive X-ray fluorescence spectrometers in rapid determination of cadmium in rice, and verify the applicability of this method for detection of cadmium in rice. Methods The typical X-ray fluorescence spectrometers of different manufacturers were selected, and the limits of qualitative and quantitative detection were evaluated by the actual samples. Detection efficiency and periodic stability were evaluated by batch samples. The effects of different forms of rice (brown rice and refined rice), determination time and frequency on the determination of cadmium in rice were determined by X-ray fluorescence spectrometer. At the same time, the differences between different brands of instruments were compared. Results The limits of quantitation of two XRF instruments were less than 0.2 mg/kg which was the maximum limit of cadmium in rice. The correlation coefficients (r2) of standard working curves were over 0.99, the relative standard deviations were less than 20%, and the coefficients of variations were less than 3% within 150 d. Though the detection time for each sample was less than 20 min, the batch samples had longer detection time. Conclusion The sensitivity of the energy dispersive X-ray fluorescence spectrometers can meet the rapid detection requirements of cadmium in rice. The different morphologies of rice have no significant effect on the detection results of X-ray fluorescence spectrometer. With the increase of detection time and parallel times, the detection results are closer to the reference value. There are different degrees of false negative and false positive problems in the two XRF instruments.