在法庭科学研究领域,指甲作为一种新型生物信息载体,在物证信息挖掘方面具有重要的价值。人生命活动中摄入的氢、氧主要来源于饮用水、摄入的食物和空气等,其中的氢、氧稳定同位素比值信息会被指甲角蛋白记录并保存下来,这些信息可以用于推断人的生活地域变化情况,在个体身份的排查工作中具有重要的作用。本文借助元素分析-稳定同位素比质谱技术（EA-IRMS）对新疆和田、哈密和阿勒泰3个城市常住居民指甲中氢、氧稳定同位素比值进行了分析,并借助判别分析模型对指甲样本的氢、氧稳定同位素比值进行了模式识别。结果表明,3个不同城市常住居民指甲氢、氧稳定同位素比值存在一定的差异;和田指甲样本δ²H值与哈密、阿勒泰有明显差异;哈密指甲样本δ²H值与阿勒泰重叠范围宽,差异较小;3个城市δ¹⁸O值分布均有重叠,无明显的差异。在判别模型中,通过判别函数f(x,y)=0.992x+0.046y和判别函数f(x,y)=-0.198x+1.009y对3个市共计85份样本进行判别分析,总体分类准确率为95.29 %,9个验证样本均实现了准确的归类和判定。本文研究表明,不同城市居民指甲中的氢、氧稳定同位素比值是存在一定差异的,采用EA-IRMS结合判别分析能初步实现不同城市居民的区分。

Nail is a kind of connective tissue with a thyroid structure on the back of fingertip. In the field of forensic science, nail, as a new biological information carrier, has a high application value. The hydrogen and oxygen stable isotopes in water would be continuously fixed by nail keratin and kept in the nail statically after the person ingested water, thus the temporal and spatial information of the person’s life were recorded, which is of great significance for the screening of individual identity. In this paper, the hydrogen and oxygen stable isotope in fingernails of residents in Khotan, Hami and Altay were analyzed by Elemental Analyses-Stable Isotope Ratio Mass Spectrometry, and the model was constructed by discriminant analysis to carry out the pattern recognition. The results showed that the ratios of hydrogen and oxygen stable isotopes in the fingernails of residents in three different cities were different. There was a significant difference between the δ²H value in Khotan residents and that in Hami and Altay. Hami and Altay had more overlapping of δ ²H value, but the difference was relatively small. The distribution of δ ¹⁸O value about three cities was overlapped without any significant difference. In the discriminant model, the difference between Khotan and Hami, Altay was very obvious, while difference between Hami and Altay was partly coincidence. Compared with DF₂ discriminant function, each sample was obviously distinct from each other under DF₁ discriminant function. The overall classification accuracy of 85 samples was 95.29 %, and the 9 verified samples were classified exactly, which was ideal. In conclusion, the combination of EA-IRMS and discriminant analysis can provide an accurate and effective method for the analysis of hydrogen and oxygen stable isotopes in fingernails of different urban residents, which has certain reference significance.