A chemometric strategy for forensic analysis of condom residues: Identification and marker profiling of condom brands from direct analysis in real time-high resolution mass spectrometric chemical signatures
A chemometric strategy for forensic analysis of condom residues: Identification and marker profiling of condom brands from direct analysis in real time-high resolution mass spectrometric chemical signatures
复制标题
DOI：
10.1016/j.talanta.2018.09.101
复制
发表时间：
2019-03-01
期刊：
影响因子：
6.1
通讯作者：
Musah, Rabi A.
中科院分区：
文献类型：
--
作者：
Coon, Allix M.;Beyramysoltan, Samira;Musah, Rabi A.
在性侵犯案件中，为了避免留下犯罪DNA证据，攻击者使用了避孕套，快速准确地识别避孕套衍生的润滑剂痕迹变得更加重要。以前的报告已经证明，可以使用各种技术来确认给定的残留物是安全套衍生的，基于对杀精剂、滑爽剂和/或其他常见添加剂的检测。然而，在区分各种不同品牌的避孕套类型方面取得的成功有限。在这项研究中，实用的直接分析在真实的时间-高分辨率质谱（DART-HRMS）结合化学计量学，快速，准确的属性的品牌避孕套残留的各种类型，进行了探索和发展。避孕套残留物光谱数据库包括110种不同的避孕套类型，代表16个品牌，与光谱作为每个品牌的代表性指纹。在应用偏最小二乘判别分析（PLS-DA）之前，对光谱指纹进行预处理，偏最小二乘判别分析（PLS-DA）用于生成允许识别避孕套品牌的分类器，准确率为97.4%。对PLS-DA施加了额外的标准，以提供每个预测的置信水平和可信度。沉积时间的影响，污染物的存在和残留物转移对模型的预测准确性的影响也进行了评估。稀疏判别分析（SDA）和PLS-DA的结果，其次是学生的t-检验的应用程序，以确定m/z值代表的小分子标记，是最重要的定义品牌类。发现由两种方法揭示的m/z值在指示哪些质量代表标志物方面是一致的。SDA方法还提供了避孕套残留物分类的判别方向的低维视图，从而使指示的m/z值和品牌歧视之间的关系易于可视化。结果进一步揭示了在代表16个品牌的所有110个避孕套中观察到的14个m/z值的子集，其中一些可能作为潜在的通用小分子避孕套标记物。总体而言，结果表明，DART-HAMS避孕套残留物光谱数据库可用于根据每个品牌特有的化学成分差异识别残留物。该数据库可以随时扩大，以包括更多的避孕套。
The rapid and accurate identification of condom-derived lubricant traces takes on heightened importance in sexual assault cases where the assailant has used a condom in order to avoid leaving behind incriminating DNA evidence. Previous reports have demonstrated that a variety of techniques can be used to confirm that a given residue is condom-derived, based on the detection of spermicides, slip agents and/or other common additives. However, limited success has been achieved in differentiating brands from among a broad range of condom types. In this study, the utility of direct analysis in real time-high resolution mass spectrometry (DART-HRMS) combined with chemometrics, for the rapid and accurate attribution of brands to condom residues of various types, was explored and developed. A database of condom residue spectra comprised of 110 different condom types representing 16 brands was generated, with the spectra serving as representative fingerprints for each brand. The spectral fingerprints were subjected to pre-processing prior to the application of Partial Least Squares-Discriminant Analysis (PLS-DA) which was used to generate a classifier that permitted identification of condom brands with an accuracy of 97.4%. An additional criterion was imposed on the PLS-DA to provide the confidence level and credibility of each prediction. The effect of time since deposition, the presence of contaminants and the influence of residue transfer on the prediction accuracy of the model were also assessed.The results from Sparse Discriminant Analysis (SDA) and PLS-DA were followed by application of the Student's t-test to determine m/z values representative of small-molecule markers that were most important for defining brand classes. The m/z values revealed by the two methods were found to be consistent in indicating which masses were representative of markers. The SDA method also provided low-dimensional views of the discriminative directions for classification of condom residues, thereby enabling easy visualization of the relationship between the indicated m/z values and brand discrimination. The results further revealed a subset of 14 m/z values that were observed in all 110 condoms representing the 16 brands, and some of these may serve as potential universal small-molecule condom markers. Overall, the results show that the DART-HAMS database of condom residue spectra can be used to identify residues based on differences in chemical components peculiar to each brand. The database can be readily expanded to include more condoms.