High-accuracy total reflection X-ray fluorescence analysis for determining trace elements using substrate cleaned by ammonia-hydrogen peroxide mixture

Tsugufumi Matsuyama; Yudai Tanaka; Yoshihiro Mori; Kouichi Tsuji

doi:10.1016/j.talanta.2023.124808

High-accuracy total reflection X-ray fluorescence analysis for determining trace elements using substrate cleaned by ammonia-hydrogen peroxide mixture

Talanta. 2023 Dec 1:265:124808. doi: 10.1016/j.talanta.2023.124808. Epub 2023 Jun 12.

Authors

Tsugufumi Matsuyama¹, Yudai Tanaka², Yoshihiro Mori³, Kouichi Tsuji²

Affiliations

¹ Division of Science and Engineering for Materials, Chemistry and Biology Department of Chemistry and Bioengineering, Osaka Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi, Osaka, 558-8585, Japan. Electronic address: t-matsuyama@omu.ac.jp.
² Division of Science and Engineering for Materials, Chemistry and Biology Department of Chemistry and Bioengineering, Osaka Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi, Osaka, 558-8585, Japan.
³ Graduate School of Business, Doshisha University Karasuma-higashi-iru, Imadegawa-dori, Kamigyo, Kyoto, 602-8580, Japan.

PMID: 37354625
DOI: 10.1016/j.talanta.2023.124808

Abstract

Total reflection X-ray fluorescence (TXRF) analysis is one of the useful techniques for determining trace elements. Owing to the high detection sensitivity of X-ray fluorescence in small residues, the hydrophobic substrates are generally used to form dot-type residue. However, when measuring low-Z elements in sample solutions with high concentrations of matrix elements, obtaining sufficient measurement sensitivity can be difficult. X-ray fluorescence is absorbed by the matrix elements, which means that the absorption effect increases in the thicker dried residue compared to the thinner dried residue. To avoid this absorption effect, we have proposed a thin film-type residue. In this study, the glass substrate was treated with an ammonia-hydrogen peroxide mixture (APM). The hydrogen peroxide decomposes organic components, and ammonia slightly etches glass materials. The APM-treated region was limited to a diameter of 6 mm by using a polytetrafluoroethylene mask placed on the glass substrate. As a result, the surface is refreshed to expose the hydroxyl group to make it superhydrophilic. The measured contact angle was 5°. By using the APM-treated superhydrophilic substrate to prepare dried residue, the net intensities in low Z elements were improved. The ratio of Al Kα intensity, calculated as net intensity in the APM-treated substrate divided by it in the hydrophobic substrate, was 2.29. The recovery of each element in the APM-treated substrate was almost 100%; however, recoveries of elements (Al, P, K, and Ca) in the hydrophobic substrate showed significant deviations from 100% (the recovery of Al was approximately 32%). In summary, we successfully improved both analytical sensitivity and accuracy in TXRF analysis by using the APM treated substrate.

Keywords: Ammonia-hydrogen peroxide mixture; Dried residue; Substrate cleaning/ hydrophilization; Total reflection X-ray fluorescence analysis.