Scottsdale Police Department Crime Laboratory, Scottsdale, Arizona, USA.
J Forensic Sci. 2021 Sep;66(5):1966-1972. doi: 10.1111/1556-4029.14796. Epub 2021 Jul 27.
Ethanol stability in antemortem blood stored under various conditions has been widely studied. Most such studies have somewhat limited sample size (<50) and limited variation in the length of time between the blood draw and the first analysis and between the first analysis and the reanalysis. In the work presented here, the antemortem blood drawn for forensic purposes and stored refrigerated (~4°C) in 371 cases was analyzed for ethanol concentration using headspace gas chromatography at various times after the blood draw based on routine case flow and then also analyzed at various times within approximately 1 year after the first analysis. This methodology is intended to provide insight into the range of differences expected when cases are analyzed in the normal flow of casework and then reanalyzed at random times afterwards as occurs when reanalysis is performed by the defense or by the laboratory if the original analyst is unavailable to testify. In 22 cases, the same blood tube from the case was reanalyzed. The previously unopened blood tube from the case was analyzed in 349 cases. The 25 cases in which the blood was ethanol-negative based on the first analysis remained ethanol-negative when reanalyzed. The average difference in ethanol concentration between tests for the ethanol-positive cases was -0.004 g/dL. This decrease was statistically significant at the 0.05 level of significance. The range of differences was -0.0197 to 0.0103 g/dL. The difference measured in 85% of the ethanol-positive cases was in in the range of -0.008 to -0.001 g/dL.
已广泛研究了在不同条件下储存的生前血液中的乙醇稳定性。大多数此类研究的样本量有些有限（<50），并且从采血到第一次分析以及从第一次分析到重新分析之间的时间长度变化有限。在本文介绍的工作中，根据常规案件流程，对为法医目的而采集并冷藏（~4°C）在 371 个案例中的生前血液进行了乙醇浓度分析，然后在第一次分析后大约 1 年内的不同时间进行了分析。该方法旨在深入了解在正常案件工作流程中进行分析，然后在以后的随机时间进行重新分析时，预计会出现的差异范围，这是当重新分析是由辩方进行或如果原始分析师无法作证，实验室进行时会发生的情况。在 22 个案例中，对来自同一案件的同一血样管进行了重新分析。在 349 个案例中分析了来自同一案件的先前未开封的血样管。根据第一次分析，25 个案例的血液乙醇检测结果为阴性，重新分析结果仍为阴性。乙醇阳性案例中两次测试之间的乙醇浓度平均差异为-0.004 g/dL。这种下降在 0.05 的显著性水平上具有统计学意义。差异范围为-0.0197 至 0.0103 g/dL。85%的乙醇阳性案例中测量的差异在-0.008 至-0.001 g/dL 之间。
