衰减全反射红外光谱对易燃液体的快速筛选

纵火是一种严重危害公共安全和社会稳定的个人极端暴力犯罪行为。在纵火案件调查过程中，火灾残留物中的易燃液体(ILs)是确定火灾性质和判断起火原因的重要物证，ILs的分析一直是法庭科学工作者关注的热点。利用衰减全反射红外光谱法(ATR-FTIR)对汽油、柴油、煤油、植物油等常见ILs进行检验，结合主成分分析(PCA)、层次聚类分析(HCA)、判别分析(DA)三种化学计量学方法，实现了常见易燃液体的快速筛选。通过红外光谱定性分析，汽油、柴油、植物油与含氧有机溶剂的红外光谱图差异明显，可相互区分，而柴油、煤油、航空煤油、溶剂油、汽轮机油五类ILs的红外谱图无明显差异，仅通过图谱的直接比较，无法进行区分。重点选取1 136~976 cm-1范围的红外特征吸收峰，结合PCA，PCA-HCA，PCA-DA化学计量学方法进行比较，成功将航空煤油与与其余四类ILs区分开；最后选取837～400 cm-1范围的红外特征吸收峰，利用PCA，PCA-HCA，PCA-DA方法，可将其余四种ILs实现互相区分。研究结果表明，ATR-FTIR结合化学计量学方法对常见ILs进行定性分析，具有方便、快捷、准确的优点，可作为ILs种类的快速筛选方法。

Study on Rapid Screening of Ignitable Liquid by Attenuated Total Reflection Infrared Spectroscopy

As a destructive criminal behavior, arson has brought serious losses to public safety and social stability. Subject to the destruction of fire and fire fighting behavior, most evidence has become beyond recognition. It brings a great difficulty in determining the direction of investigation and a fair trial of criminal suspect. The ignitable liquids at fire scenes are important evidence to judge the case nature. And the types determination is the key point of criminal identification. In this paper, the rapid screening method of common Ignitable Liquid was established by attenuating total reflection infrared (ATR-FTIR) spectroscopy combined with PCA, HCA and DA. The IR spectra of gasoline, diesel oil, vegetable oil and oxygenated organic solvents were significant different and by virtue of this, mutual distinction can be achieved. But there was no significant difference in IR spectra of diesel, kerosene, aviation kerosene, solvent oil and turbine oil and only by direct comparison can not achieve mutual distinction. Next, the IR absorption range (1 136~976 cm-1) combined with chemometric tools (PCA，PCA-HCA，PCA-DA) was used for separating aviation kerosene from the remaining four types of ILs. Finally, the infrared absorption peaks in the range of 837~400 cm-1 were selected, and the other four kinds of ILs were distinguished by PCA, PCA-HCA and PCA-DA chemometrics methods. Our experimental results showed that ATR-FTIR can provide sufficient information on ignitable liquids. Combined with some chemometrics methods, ATR-FTIR successfully completed the qualitative analysis of common ILs. Once the model is established, this method becomes convenient and accurate, and can be applied to rapid screening of ILs types.