法庭科学中泥土物证XRF检验数据的分析研判

目的 对元素分析产生的大量数据进行统计,从而达到准确对样品进行区分和归类的目的.方法 利用X射线荧光光谱法对从北京郊区10个区县、辽宁沈阳、安徽泗县、四川泸州、山东威海和广西南宁提取的225个泥土样品进行元素定量分析.采用SPSS软件中欧氏距离计算泥土样品间的差异,利用主成分分析法进行样品归类.结果 确定了不同空间距离样品间差异的欧氏距离的阈值.主成分分析法可对225个泥土进行较为准确的分类.结论 欧氏距离值可为泥土样品的比对提供量化比对依据,利用主成分分析法可推断未知泥土样品的来源.

Data Analysis of Elemental Examination of Soil Evidence by XRF in Forensic Science

Objective To correctly discriminate and classify soil samples by statistical analysis of elemental examination results.Method 225 various soil samples collected from Beijing suburbs,Shenyang,Sixian,Luzhou and Nanning,were analyzed by Xray fluorescence spectrometry（XRF）.Euclidean distance and Principle Component Analysis（PCA） were carried out to assess the difference of these soil samples.Results Critical values were evaluated to estimate the difference of soil samples collected from locations in different spatial distance.PCA method could classify these soil samples effectively.Conclusion Euclidean distance can provide quantitative basis for the comparison of soil samples and principle component analysis can be used to deduct the origin of unknown soil samples.