Forensic Discrimination of Heated and Non-Heated Sheet Glasses by Analysis of Trace Impurities Using SR-XRF

Abstract

The application of trace impurity analysis using synchrotron radiation X-ray fluorescence spectrometry (SR-XRF) was investigated for the forensic discrimination of heated and non-heated sheet glasses. Each of 5 sheet glasses produced by 3 domestic manufacturers was divided into 2 groups, one of which was subjected to RI measurement and elemental analysis by SR-XRF after heating at 764°C for 2 minutes while the other was without heating. All of the heated glasses provided lower RI values than those of non-heated ones. The difference in RI between the heated and non-heated glasses ranged from 0.0012 to 0.0015, which was 6∼7 times larger than the variation of RI within a pane of sheet glass. As a result of the elemental analysis of 5 non-heated glasses by SR-XRF, the X-ray intensities of impurity elements, such as Rb, Sr, Zr, Ba, La and Ce, were found to be considerably different among the different glasses. All of 10 pairs among 5 non-heated glasses could be successfully discriminated by comparisons of 4 kinds of X-ray intensity ratios (SrKα/RbKα, ZrKβ/RbKα, BaKα/CeKα, LaKα/CeKα). No significant difference was recognized between the analytical results of the non-heated glasses and those of heated ones by the t-test with a significance level of 1%. It is concluded that trace impurity analysis using SR-XRF is useful for the correct discrimination of heated and non-heated glass fragments, whereas the comparison of only RI can result in false differentiation.