Whole blood and semen identification using mid-infrared and Raman spectrum analysis for forensic applications

The identification of body fluids is important in forensic science. This paper describes the application of mid-infrared and Raman spectroscopies in the non-destructive identification of human blood and semen, where other detailed information can also be obtained in one single measurement. Samples of human blood and semen were probed and characterized utilizing Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) and confocal Raman spectroscopies. The result shows their ability to identify an unknown substance to be human blood or semen without the use of chemical reagents. Age determination of dried blood and semen spots through their mid-infrared spectra was investigated, which could probably be used during forensic casework. Furthermore, the origin of the Raman scattering peaks of human semen at 2907 and 2968 cm −1 is detailedly analyzed, which has not been studied in previous literature. Overall, this optical detection and identification method exhibits advantages over conventional chemical methods in terms of non-destruction, high sensitivity, rapid detection and direct confirmation. The identification of body fluids is important in forensic science.