利用紫外可见反射光谱鉴定血迹陈旧度

Authentication of Age of Bloodstains Using UV Visible Reflection Spectrum

凶杀案的血迹陈旧度与案发时间有着必然联系,推断案发时间对于侦破案件具有重要意义,也是司法鉴定中的一个难题,建立一种快速确定出血时间的方法非常必要。使用UV-2450型紫外可见分光光度计,ISR-240A积分球附件,BaSO4标准白板参比,测定16℃、湿度70%条件下血迹纱布、铝片、玻璃、保鲜膜的8h内每间隔1h的反射光谱,同样方法测定24℃、湿度70%条件下血迹纱布的反射光谱,利用SPSS软件处理,求出541和577nm反射率比值(R541/R577),进行直线拟合,建立线性回归方程,进行F检验。随着时间的增加,血迹在541和577nm处的反射率增加,除了带血迹玻璃的R2为0.769外,其余R2均大于0.900,F均大于F0.05(1,6)=5.59,线性回归模型有显著意义。利用紫外可见光谱仪积分球附件可以实现一定环境载体条件下8h内血迹陈旧度推断,方法操作简单,不需要对检验对象进行任何处理,保证了其完整性,不影响对其进一步的个人信息等方面的检验,适合司法实践中的需求。

The age of bloodstains is tightly related to the time elapsed since the crime was committed.The inference of the time that the crime was committed is of great significance to solve the case,and it was also a difficult problem in judicial authentication.Therefore,establishing a method of rapid determination of bleeding time is very necessary.Using a UV-visible spectrometer with a reflection accessory called ISR-240 Aand whiteboard as a reference standard,the reflection spectra of blood gauze,aluminum,glass and plastic were measured every hour under the condition of 16℃ and 70% humidity within 8hours.Using SPSS to process the data,R541/R577 was figured out and linear fitting was completed.The same method was carried on on the gauze of blood at 24℃.The results showed that,within 8hours,spectral reflectance values of blood at 541 and 577nm increased gradually with the passage of injury time.In addition to the R^2 of the glass with blood is 0.769,the rest of the R^2 were greater than 0.900.The values of F were greater than F0.05（1,6）=5.59.Therefore,the linear regression model is significant meaningful.The method of using a UV-Visible spectrometer without doing any operations of the test samples is simple.Moreover,it does no harm to the further inspection in aspects of personal information,which is suitable for the judicial practice.