An inter-laboratory evaluation of LA-ICP-MS analysis of glass and the use of a database for the interpretation of glass evidence
An inter-laboratory evaluation of LA-ICP-MS analysis of glass and the use of a database for the interpretation of glass evidence
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DOI：
10.1016/j.forc.2018.10.001
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发表时间：
2018-12-01
影响因子：
2.7
通讯作者：
Almirall, Jose
中科院分区：
文献类型：
--
作者：
Hoffman, Tricia;Corzo, Ruthmara;Almirall, Jose
10个进行法医玻璃分析的实验室参加了三次实验室间演习，以评估标准方法的使用情况（ASTM 2927- 16 e1），用于使用LA-ICP-MS分析和比较玻璃证据。本研究旨在评估当盲玻璃样品分发给参与者并要求比较玻璃样品时的误导性证据（罗马）率（K vs. Q）并像在案例中一样报告他们的发现。三个不同的数据库被用作背景人口来计算似然比（LR）和频率的元素配置文件。第一个数据库由420个汽车挡风玻璃样品组成，本文首次报道了该数据库的分析数据和应用。第二个数据库由德国的BKA实验室提供，代表385个个案样品，包括浮法玻璃、容器玻璃和特种玻璃的分类。第三个背景数据库是两个数据库的组合。在第一次实验室间试验中，似然比（LR）计算结果为34/36（94.4%）正确关联，所有实验室均无错误包含。在第二次和第三次实验室间比对中，所有参与的实验室都正确地将来自同一来源的玻璃样品联系起来（57次比对），所有实验室都正确地区分了来自不同来源的玻璃样品（167次比对）。已知来自不同玻璃来源的玻璃样品的随机匹配概率被发现与0.1%相似，并且与其他研究人员先前报道的值一致。
Ten laboratories conducting forensic glass analysis participated in three inter-laboratory exercises to evaluate the use of a standard method (ASTM 2927-16e1) for the analysis and comparison of glass evidence using LA-ICP-MS. This study was designed to evaluate the rate of misleading evidence (ROME) when blind glass samples were distributed to the participants and asked to compare the glass samples (K vs. Q) and report their findings as they would in a case. Three different databases were used as background populations to calculate likelihood ratios (LRs) and frequency of elemental profile. The first database was composed of 420 vehicle windshield samples and the analytical data and application of this database is reported here, for the first time. The second database was provided by the BKA laboratory in Germany representing 385 casework samples including an assortment of float glass, container glass, and specialty glasses. The third background database was a combination of both databases. In the first inter-laboratory exercise, the likelihood ratio (LR) calculations result in 34/36 (94.4%) correct associations and no false inclusions for all labs. LRs in the second and third inter-laboratory exercises result in all participating laboratories correctly associating glass samples originating from the same source (57 comparisons) and all laboratories correctly discriminating glass samples from different sources (167 comparisons). The random match probability of glass samples known to originate from different glass sources was found to be similar to 0.1% and in agreement with previously reported values by other researchers.