Yildirim Mahmut Şerif, Akçan Ramazan, Aras Sümer, Tamer Uğur, Evran Eylül, Taştekin Burak, Aydogan Canberk, Boyaci İsmail Hakkı
Department of Forensic Medicine, Afyonkarahisar Health Sciences University, Afyonkarahisar, Turkey.
Department of Forensic Medicine, Hacettepe University, Ankara, Turkey.
Forensic Sci Int. 2023 Mar;344:111607. doi: 10.1016/j.forsciint.2023.111607. Epub 2023 Feb 15.
Blood and semen stains are the most common biological stains encountered at crime scenes. The washing of biological stains is a common application that perpetrators use to spoil the crime scene. With a structured experiment approach, this study aims to investigate the effects of washing with various chemicals on the ATR-FTIR detection of blood and semen stains on cotton.
On cotton pieces, a total of 78 blood and 78 semen stains were applied, and each group of six stains was immersed or mechanically cleaned in water, 40% methanol, 5% sodium hypochlorite solution, 5% hypochlorous acid solution, 5 g/L soap dissolved pure water, and 5 g/L dishwashing detergent dissolved water. ATR-FTIR spectra gathered from all stains and analyzed with chemometric tools.
According to performance parameters of developed models, PLS-DA is a powerful tool for discrimination of washing chemical for both washed blood and semen stains. Results from this study show that FTIR is promising for use in detecting blood and semen stains that have become invisible to the naked eye due to washing of the findings.
Our approach allows blood and semen to be detected on cotton pieces using FTIR combined with chemometrics, even though it is not visible to the naked eye. Washing chemicals also can be distinguished via FTIR spectra of stains.
血迹和精液污渍是犯罪现场最常见的生物污渍。清洗生物污渍是犯罪者破坏犯罪现场的常用手段。本研究采用结构化实验方法，旨在探究用各种化学物质清洗对衰减全反射傅里叶变换红外光谱（ATR-FTIR）检测棉花上血迹和精液污渍的影响。
在棉布片上施加总共78处血迹和78处精液污渍，每组6处污渍分别浸入或用机械方法在水中、40%甲醇、5%次氯酸钠溶液、5%次氯酸溶液、5 g/L肥皂溶解的纯水以及5 g/L洗洁精溶解的水中进行清洗。收集所有污渍的ATR-FTIR光谱并用化学计量工具进行分析。
根据所建立模型的性能参数，偏最小二乘判别分析（PLS-DA）是区分清洗血迹和精液污渍所用化学物质的有力工具。本研究结果表明，傅里叶变换红外光谱（FTIR）有望用于检测因清洗而肉眼不可见的血迹和精液污渍。
我们的方法能够利用傅里叶变换红外光谱结合化学计量学在棉布片上检测出血迹和精液污渍，即便肉眼不可见。通过污渍的傅里叶变换红外光谱也能够区分清洗所用的化学物质。
