现场嗅源气味在不同材质上存留特性研究

The Remaining Characteristics of Body Odor Left on Different Material Surfaces

目的探索嗅源气味在不同介质上的存留特性,为现场勘查人员提供技术支持。方法采用风洞技术控制环境因素,以人体气味中的棕榈酸、十二烷酸、十三烷酸、十四烷酸、十五烷酸等5种气味化合物作为浓度衰减标记物,采用GC/MS分析技术,研究遗留在大理石、木制品、棉制品、土块等4种不同材质表面的嗅源气味浓度变化规律。结果随着时间的延长,附着于不同材质表面的嗅源气味的浓度呈递减趋势。24 h后,存留于大理石、木制品、土块、棉制品表面的嗅源气味分别为原始浓度的12%、16%、30%和35%。结论在实际警犬技术工作中,选择棉制品、木质品、土块等作为嗅源的提取物,在相同时间条件下,附着嗅源气味的量要大于附着大理石等硬质材料的量。

Objective The odor from different people is very useful for prevention and fighting against crime, especially when canines are used to discriminate it. In order to support the crime scene investigation, we have explored the remaining characteristics of human body odor left on different material surfaces including marble, wood, cotton and clay. Methods A homemade wind tunnel was used to model the environmental factors in the crime scene. These factors include temperature, wind speed and moisture, being respectively set to 20 ℃, 1.6 m/s and 35 %. GC/MS was used for the detection of remaining characteristics of the body odor that is indicated by five marker compounds： dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid and hexadecanoic acid. The temperature for MSD transfer line was set at 280 ℃. The temperature for ion source and quadrupole was set at 230 ℃ and 150 ℃, respectively. Electron ionization mode was used at 70 e V with a scanning rate of 3scans/s over the mass range of m/z 30-350 amu. The samples were collected by them（marble, wood, clay, or cotton） being grabbed or pressed with hand. Seven samples in a group of the same people, were used to test the variance of odor concentration during 24 hours on the same sampling object. Solid Phase Micro-Extraction kit was used to extract each sampling object every four hours. In data processing, the 0 hour＇s sample was the reference, whose concentration was assigned to 100% to normalize the other samples＇. Results The odor concentration on different material surfaces decreased with time elapsing. The concentrations of body odor adsorbed onto the surface of marble, wood, clay and cotton were as many of 30 %, 34 %, 57 % and 63 % as the initial concentrations. After 24 hours, the remaining odor on marble, wood, clay and cotton were left of 12 %, 16 %, 30 % and 35 %, respectively. The result demonstrated that at the same environment conditions, the odor adsorption capacity of the cotton was better than that of marble, wood, and/or clay. Conclusion In crime scene investigations, the odor samples from the wood, cotton and/or clay were greater than that from marble.