基于ATR-FTIR光谱技术研究血痕形成的时序性变化

Study on the time-dependent changes of blood stain formation using ATR-FTIR spectroscopy

目的应用衰减全反射-傅里叶变换红外(ATR-FTIR)光谱技术,研究血痕形成过程中主要化学基团的变化趋势,为今后构建血痕形成时间推断模型建立实验基础。方法采6例人体外周血样,各取1滴从10 cm高处滴于ATR探头,每10 min采集一次FTIR光谱数据,共持续72 h。运用Matlab 2018a软件分析光谱数据,分别对主要吸收峰的吸光度值、峰面积值(x)和血痕形成时间(y)进行拟合。结果血痕形成大致可以分为两个阶段,血液干涸阶段(0-40 min)和血痕形成阶段(>40 min)。第二个阶段,主要吸收峰峰形稍有改变,但峰位没有明显变化。不同吸收峰吸光度值随时间变化趋势较差;而对应峰面积值变化趋势较好,且多符合对数函数变化规律。结论血痕形成FTIR光谱分析,吸收峰的峰面积优法于吸光度法。绝大多数化学基团不断分解,主要呈先快后慢趋势;不同物质分解速率不同,同一物质不同基团、同一基团不同振动类型变化趋势亦不相同。其中,1641、1537、2958及1080 cm^-1吸收峰降解趋势较为规律。

Objective To study the time-dependent changes of main chemical goups in the process of bloodstain formation with attenuated total reflection–Fourier transform infrared(ATR-FTIR)spectroscopic technology,and to establish the experimental and theoretical basis for constructing relatively accurate and reliable time inference mathematical model of blood stain formation.Methods One drop of blood,respectively from six healthy adult volunteers,was dropped directly onto the ATR crystal from 10 cm height.The FTIR spectra were recorded every 10 minutes,72 h.total.Matlab 2018 a was used to analyze the spectroscopic data.The different absorbance or areas of peaks were calculated.The curve estimation analysis between absorbance or areas of peaks(x)and time of blood stain formation(y)were performed to establish mathematical models.Results The process of blood stain formation can be roughly divided into the drying(0-40 min)and the formation stage(>40 min).In the second stage,the shape of different absorption peaks changed with position unchanged.The areas of absorbance peak conform to the rule of logarithmic function,and work better than the absorbance values.Conclusions The spectra of blood stain formation could be interfered by the environment.Majority chemical groups in the blood stain decompose continuously,,mainly showing the trend of first fast and then slow.The decomposition rates of different components varies.Besides,the change trend of different groups from the same substance and vibration types from the same chemical groups are also different.The degradation trends of 1647,1537,2958 and 1080 cm^-1 absorbance peaks are more regular and deserve further research.