Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT 84112, USA.
Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT 84112, USA; Department of Archaeology, University of York, King's Manor, York YO1 7EP, UK; División Arqueología, Universidad Nacional de La Plata, Paseo del Bosque s/no B1900FWA, La Plata, Buenos Aires, Argentina.
Sci Justice. 2024 Mar;64(2):193-201. doi: 10.1016/j.scijus.2024.01.004. Epub 2024 Feb 2.
Isotopic analysis of human tooth enamel can provide life history information useful in forensic identification. These applications depend on the availability of reference data documenting isotopic values for individuals with known life history and on the comparability of data from reference and case work samples. Here we build on previous methodological research, which has largely focused on paleontological and archaeological samples, and conduct experiments using enamel from modern human teeth targeting three sample preparation variables (sample particle size, storage conditions, and chemical pretreatments). Our results suggest that differences in particle size affect the efficiency of sample reactions during pretreatment and analysis, with coarse particles giving reduced loss of enamel carbonate during acid pretreatments but producing slightly higher oxygen isotope values than fine particles during analysis. Data for samples stored in dry and ambient environments following pretreatment were indistinguishable, suggesting no exchange of oxygen between samples and ambient water vapor. Finally, chemical pretreatments with a range of commonly used reactants and conditions showed a pervasive, moderate oxygen isotope shift associated with acetic acid treatment, which may be caused by exchange of enamel hydroxyl groups with reagents or rinse waters. Collectively, the results emphasize the importance of methodological standardization to improve comparability and reduce potential for bias in the forensic application of tooth enamel isotope data.
对人牙釉质进行同位素分析可以提供有助于法医鉴定的生活史信息。这些应用依赖于具有已知生活史个体的同位素值的参考数据的可用性，以及参考和案例工作样本数据的可比性。在这里，我们在前人主要关注古生物学和考古学样本的方法学研究的基础上，针对三个样品制备变量（样品粒径、储存条件和化学预处理），使用现代人类牙齿的牙釉质进行实验。我们的结果表明，粒径的差异会影响预处理和分析过程中样品反应的效率，粗颗粒在酸预处理过程中减少了牙釉质碳酸盐的损失，但在分析过程中产生的氧同位素值略高于细颗粒。预处理后在干燥和环境条件下储存的样品数据无法区分，表明样品与环境水蒸气之间没有氧气交换。最后，一系列常用反应物和条件的化学预处理显示出与乙酸处理相关的普遍、适度的氧同位素偏移，这可能是由于牙釉质羟基与试剂或冲洗水发生交换所致。总的来说，这些结果强调了方法标准化的重要性，以提高可比性并减少法医应用牙釉质同位素数据时出现偏差的可能性。
