ОЦЕНКА АНАЛИТИЧЕСКИХ ВОЗМОЖНОСТЕЙ РЕНТГЕНОФЛУОРЕСЦЕНТНОЙ СПЕКТРОМЕТРИИ С ПОЛНЫМ ВНЕШНИМ ОТРАЖЕНИЕМ ПРИ АНАЛИЗЕ НАПИТКОВ С МАТРИЦЕЙ САХАРОЗЫ

Abstract

Multielement analysis of food products, including drinks, is important for an assessment of the content of the useful and toxic elements for the human body. In this paper, the main problems and their solutions in the analysis of sugar-containing drinks by Total Reflection X-ray Fluorescence Spectrometry ( TXRF ) method have been considered. The organic sucrose matrix causes certain difficulties both in the preparation of the samples and in the processing of measurement data for TXRF. The following most common sample preparation procedures for TXRF were considered: direct, based on the analysis of initial sample, dilution with water and acid digestion. In order to assess the fulfillment of the thin layer criterion, the physical characteristics of dried samples on the carriers were determined after applying each of the above-mentioned preparation procedures, and the corresponding surface density values were established. The obtained values were compared with the theoretical ones. Based on the calculation of mass absorption coefficients for C 12 H 22 O 11 matrix, it was found that the method of acid digestion was suitable for the quantitative determination of light (14 < Z < 20) elements. When analyzing the sample without the preliminary preparation or after diluting the sample with water, the influence of absorption effects was noted due to the mismatch of the surface density with the thin layer criterion. This mismatch of the samples in the direct analysis was confirmed by the measurements using a method based on an angle incidence scanning of the primary radiation on the sample, establishing a violation of the conditions for the effect of total external reflection. The detection limits were calculated for the considered sample preparation procedures, and it was concluded that the quantitative identification of Fe, Ni, Cu, Zn, Rb, Sr, and Pb trace elements at the level of tens of μg/l was possible by the acid digestion procedure. The application of the addition method to assess the trueness of elemental determination led to the conclusion that it was possible to use the direct analysis of sugar-containing drinks for the elements with Z ≥ 24 in the concentration ranges of 0.5–10 mg/l. Key words : X-ray fluorescence, TXRF, soft drinks, matrix effects, absorption effects, sucrose, multielement analysis, addition method (Russian) DOI: http://dx.doi.org/10.15826/analitika.2019.23.4.009 A.S. Maltsev 1, 2 , A. von Bohlen 3 , R.A. Yusupov 2 , S.A. Bakhteev 2 1 Institute of the Earth’s Crust, SB RAS, Lermontov st., 128, Irkutsk, 664033, \xa0Russian Federation 2 Kazan National Research Technological University, Marksa st., 68, Kazan, 420012, Russian Federation 3 Leibniz-Institut fur Analytische Wissenschften ISAS, Bunsen-Kirchhoff-Str. 11, Dortmund, 44139, Germany