Blood identification and discrimination between human and nonhuman blood using portable Raman spectroscopy

Abstract

Raman spectroscopy is commonly used in chemistry to identify molecular structure. This technique is a nondestructive analysis and needs no sample preparation. Recently, Raman spectroscopy has been shown to be effective as a multipurpose analytical method for forensic applications. In the present study, blood identification and discrimination between human and nonhuman blood were performed by a portable Raman spectrometer, which can be used at a crime scene. To identify the blood and to discriminate between human and nonhuman blood, Raman spectra of bloodstains from 11 species (human, rat, mouse, cow, horse, sheep, pig, rabbit, cat, dog, and chicken) were taken using a portable Raman spectrometer. Raman peaks for blood (742, 1001, 1123, 1247, 1341, 1368, 1446, 1576, and 1619 cm) could be observed by the portable Raman spectrometer in all 11 species, and the human bloodstain could be distinguished from the nonhuman ones by using a principal component analysis. This analysis can be performed on a bloodstain sample of at least 3 months old. The portable Raman spectrometer can be used at a crime scene, and this analysis is useful for forensic examination.

Discrimination Between Infant and Adult Bloodstains Using Micro‐Raman Spectroscopy: A Preliminary Study

“…The Raman peak assignments for blood samples are summarized in Table 2. We previously reported that peaks at 742, 1001, 1123, 1247, 1341, 1368, 1446, 1576, and 1619 cm À1 were observed in human bloodstains using a portable Raman spectrometer (9). In this study, we obtained peaks at 754, 1002, 1127, 1248, 1340, 1368, 1560, and 1611 cm À1 .…”

“…reported that high laser power can degrade the hemoglobin in bloodstains . We used 40 mW of laser power in our previous study to detect the weak peak. The peak intensity of Raman spectrum depends on the laser power.…”

“…We analyzed a range of 500–1800 cm −1 according to Virkler et al. and our past study . These studies reported the Raman peak assignments in the vibrational mode for bloodstains to be 742, 1001, 1123, 1247, 1341, 1368, 1446, 1576, and 1619 cm −1 .…”

“…We confirmed that the Raman spectra in the present study are consistent with the spectra reported earlier (6,12,13) and that the hemoglobin in the bloodstain was not degraded. We analyzed a range of 500-1800 cm À1 according to Virkler et al (6) and our past study (9). These studies reported the Raman peak assignments in the vibrational mode for bloodstains to be 742, 1001, 1123, 1247, 1341, 1368, 1446, 1576, and 1619 cm À1 .…”

A practical convolutional neural network model for discriminating Raman spectra of human and animal blood

“…The bands below 598 cm −1 are dominated by the quartz slide (Supplementary Materials S1), and bands beyond 1837 cm −1 have no obvious peak, so only 800 variables between 598 and 1837 cm −1 are used. The peaks between 598 and 1837 cm −1 are attributed to the vibrational absorption of the glucose, tryptophan protein, and hemoglobin of the blood according to the Table . All spectra are normalized to the range of 0 to 1 by dividing the each spectrum by its maximum value to eliminate the different scale.…”