In the reported study, attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy was used as a confirmatory, nondestructive, and rapid method for distinguishing between human and animal (nonhuman) blood.
Blood is one of the most common and informative forms of biological evidence found at a crime scene. A crucial step in forensic investigations is identifying a bloodstain’s origin. The standard methods currently used for analyzing blood are destructive to the sample and time-consuming. In the current study, partial least squares-discriminant analysis (PLS-DA) models were built and demonstrated complete separation between human and animal donors, as well as distinction between three separate species: human, cat, and dog. Classification predictions of unknown blood donors were performed by the model, resulting in 100-percent accuracy. This study demonstrates ATR FT-IR spectroscopy’s great potential for blood stain analysis and species discrimination, both in the lab and at a crime scene, since portable ATR FT-IR instrumentation is commercially available. (publisher abstract modified)