Analytical Sciences

Application of Total Reflection X-ray Fluorescence Spectrometry to Small Glass Fragments

Yoshinori NISHIWAKI,* Masahiko SHIMOYAMA,* Toshio NAKANISHI,* Toshio NINOMIYA,** and Izumi NAKAI***

*Forensic Science Laboratory, Hyogo Prefectural Police Headquarters, 5-4-1, Shimoyamate-dori, Chuo, Kobe, Hyogo 650-8510, Japan
**Japan Synchrotron Radiation Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
***Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku, Tokyo 162-8601, Japan

Total reflection X-ray fluorescence spectrometry (TXRF) has been applied for trace elemental analysis of small glass fragments. A small glass sample (a fragment with weight less than 0.5 mg) was decomposed by 100 µg of HF/HNO₃ acid; the material was condensed to 10 µl and was dried on a Si wafer. Since the size of the dried residue on the Si wafer was less than 1 cm in diameter, an incident X-ray beam with about 1 cm in width could effectively excite elemental components in such a small glass fragment. The precision of the present technique was checked by analyzing the glass fragments (< 0.5 mg) from NIST SRM612; the relative standard deviations (RSD) of less than 8.1% were achieved for elemental ratios that were normalized by Sr. Fragments (< 0.5 mg) obtained from 23 figured sheet glasses were used as samples for estimating the utility of this technique to forensic discrimination. Comparison of five elemental ratios of Ti/Sr, Mn/Sr, Zn/Sr, Rb/Sr, and Pb/Sr calculated from X-ray fluorescence spectra was effective in distinguishing glass fragments that could not be differentiated by their refractive indexes (RI).

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