对于食品中多无机元素的检测控制急需一种样品前处理简单快速、 检出范围广的分析方法, 因此通过考察不同分散剂、 颗粒粒径大小、 悬浊液中样品质量浓度以及内标元素对全反射X 射线荧光光谱法测试结果的影响, 建立了快速、 便捷的悬浮液进样-全反射X射线荧光光谱法测定食品中多无机元素的方法。 实验结果表明: 去离子水（Milli-Q water）, 聚乙二醇辛基苯基醚（Triton X-100）和硝酸三种不同分散剂中, 光学显微镜下形貌上Milli-Q water和Triton X-100作分散剂较HNO3样品分散更均匀, Milli-Q water作分散剂其测量结果较Triton X-100更准确; 试样经研磨, 并用激光衍射粒度分析仪测定试样研磨前后的颗粒粒径大小, 发现平均颗粒粒径小的样品全反射X 射线荧光光谱法测试结果准确度更高; 称取不同量样品于相同量分散剂中, 看出随着悬浮液中样品质量浓度增加, 回收率会增大或降低; 实验中分别应用Ga或Se为内标元素定量分析GBW08571贻贝样品, 但是由于所测元素As和Se是相邻元素, 引起谱线重叠, 进而Se为内标元素会影响As元素定量分析的准确度, 因此为避免内标元素对测量元素产生谱线干扰, 实验中选择Ga为内标元素。 用该方法测定了四个有证标准物质（食品类）, 四个标准物质中无机元素的测量值和标准值比较, 大多元素（除Ca元素）回收率集中在80%～120%间, RSD小于15%, 且对于不同含量范围的元素, 用该方法测定均能获得可靠的测试结果, 相对于需消解的电感耦合等离子体原子发射光谱法和质谱法的方法, 用悬浮液制样-全反射X射线荧光分析测定食品中的多元素更快速、 便捷。

A simple, rapid and wide-ranging analytical method is urgently needed for the detection and control of inorganic multi-element in foodstuff. Therefore, in this work, an analytical methodology using suspension sampling in combination with a low power benchtop total reflection X-ray fluorescence (TXRF) system has been developed for multi-elemental analysis of foodstuff samples．The effect of different dispersants, particle size, sample mass concentration in suspension and internal standard elements on the total reflection X-ray fluorescence spectrometry was investigated. The Milli-Q water, Triton X-100 and nitric acid were chosen for dispersants, under optical microscope Milli-Q water and Triton X-100 were more uniform than HNO3 in morphology, and Milli-Q water was more accurate than Triton X-100 in measuring results by TXRF. Laser diffraction particles were used to determine the particle size before and after grinding, and it was found when the average particle size was small, the results of TXRF were more accurate. Different samples were weighed in the same amount of dispersant, and the dispersion effect and test accuracy would be affected with the increase of the sample mass concentration in the suspension. Ga or Se was used as internal standard elements for quantitative analysis of GBW0857 in the experiment, but because the measured elements As and Se are adjacent elements, which cause overlap of spectral lines, and then Se as internal standard elements would affect the accuracy of quantitative analysis of As elements, in order to avoid the interference of internal standard elements on the measured elements, Ga was selected as internal standard elements in this experiment. An easy and rapid sample preparation consisting in suspending 20 mg of sample in de-ionized water showed to be the most suitable for this kind of samples. Four certified reference materials in foodstuff were employed for the quantitative determination of the inorganic elements. The recovery rate of most elements (except some elements) was concentrated in the range of 80% to 120%, and the RSD was less than 15%. Compared with the methods of ICP-AES and ICP-MS, the method of suspension sample preparation-total reflection X-ray fluorescence analysis is faster and more convenient.