Analytical Sciences

Forensic Discrimination of Sheet Glass by a Refractive-Index Measurement and Elemental Analysis with Synchrotron Radiation X-ray Fluorescence Spectrometry

Yasuhiro SUZUKI,* Masaaki KASAMATSU,* Shinichi SUZUKI,* Toshio NAKANISHI,** Masahisa TAKATSU,** Seiji MURATSU,** Osamu SHIMODA,** Seiya WATANABE,** Yoshinori NISHIWAKI,** and Naoki MIYAMOTO**

*National Research Institute of Police Science, 6-3-1, Kashiwanoha, Kashiwa, Chiba 277-0882, Japan
**Forensic Science Laboratory, Hyogo Prefectural Police H. Q., 5-4-1, Shimoyamate-dori, Chuo-ku, Kobe 650-8510, Japan

Measurements of the refractive index (RI) and elemental analysis using synchrotron radiation X-ray fluorescence spectrometry (SR-XRF) were applied to the forensic discrimination of sheet-glass samples from different origins. The refractive index was calculated from the matching temperature at which the glass fragments became invisible in silicone oil. Fragments smaller than 1 mm in maximum diameter were taken from each of 11 sheet glasses and subjected to analysis by SR-XRF. The XRF spectrum of these samples indicated that a comparison of 6 elements (Ca, Fe, Sr, Zr, Ba and Ce) was useful for the discrimination of sheet glasses. Cluster analysis was performed using 33 sets of SR-XRF data obtained by triplicate measurements for the 11 glasses. Comparing 528 pairs among 33 samples, 515 pairs could be correctly discriminated. The number of indistinguishable pairs could be reduced from 36 to 4 by comparing the SR-XRF data. Elemental analysis by SR-XRF could provide small glass fragments with a more evidential value than the solely measurement of only RI, through a significant improvement of the discrimination capability.

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