Analysis of lead isotopic ratios of glass objects with the aim of comparing them for forensic purposes

作者：Martyna Agnieszka; Sjastad Knut Endre; Zadora Grzegorz^*; Ramos Daniel

来源：Talanta, 2013, 105: 158-166.

DOI：10.1016/j.talanta.2012.11.079

• Evaluation of forensic evidence
• Glass fragments
• IRMS analysis
• Lead isotope ratios
• Likelihood ratio
• Empirical Cross Entropy

This paper presents the possibilities of applying the likelihood ratio (LR) approach for the comparison problem to the data collected as a result of the Isotope Ratio Mass Spectrometry (IRMS) analysis targeted at lead (Pb)-isotope ratios. The assessment of the applied LR models performance was conducted by an Empirical Cross Entropy (ECE) approach. 35 glass samples were subjected to IRMS analysis and were described by Pb-isotope ratios: Pb-208/Pb-204, Pb-207/Pb-204, Pb-206/Pb-204, Pb-208/Pd-206, and Pb-207/Pb-206. Univariate and bivariate LR computations were performed, assuming normally distributed data subjected or not to a logarithmic transformation. Principal Component Analysis (PCA) was employed for creating orthogonal variables to propose an alternative LR model. It was found that the application of variable Pb-208/Pb-204 seems to be promising as it delivers one of the lowest percentages of false positive and false negative rates as well as being the only variable for which an ECE plot gave satisfactory results.

• 出版日期2013-2-15
• 单位司法部司法鉴定科学技术研究所