悬浮液进样-全反射X射线荧光光谱法测定食品中的多无机元素

doi:10.3964/j.issn.1000-0593(2020)03-0945-05

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Abstract 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.

Key words：Total reflection X-ray fluorescence (TXRF); Foodstuff; Inorganic multi-element; Suspension

Received: 2019-01-27 Accepted: 2019-04-15

ZTFLH:

O655

Corresponding Authors: ZHUO Shang-jun E-mail: sjzhuo@mail.sic.ac.cn

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http://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2020)03-0945-05 OR http://www.gpxygpfx.com/EN/Y2020/V40/I03/945