Comprehensive modeling of bloodstain aging by multivariate Raman spectral resolution with kinetics

Ayari Takamura,Daisuke Watanabe,Rintaro Shimada,Takeaki Ozawa

doi:10.1038/s42004-019-0217-1

Ayari Takamura, Daisuke Watanabe + Show 2 more

Open Access

https://doi.org/10.1038/s42004-019-0217-1

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Abstract

Blood, as a cardinal biological system, is a challenging target for biochemical characterization because of sample complexity and a lack of analytical approaches. To reveal and evaluate aging process of blood compositions is an unexplored issue in forensic analysis, which is useful to elucidate the details of a crime. Here we demonstrate a spectral deconvolution model of near-infrared Raman spectra of bloodstain to comprehensively describe the aging process based on the chemical mechanism, particularly the kinetics. The bloodstain spectra monitored over several months at different temperatures are decomposed into significant spectral components by multivariate calculation. The kinetic schemes of the spectral components are explored and subsequently incorporated into the developed algorithm for the optimal spectral resolution. Consequently, the index of bloodstain aging is proposed, which can be used under different experimental conditions. This work provides a novel perspective on the chemical mechanisms in bloodstain aging and facilitates forensic applications.

Highlights

Blood, as a cardinal biological system, is a challenging target for biochemical characterization because of sample complexity and a lack of analytical approaches
To comprehensively investigate the chemical processes of bloodstain aging, we investigated the time and temperature experimentally
A salient advantage of this kinetic-based modeling approach for bloodstain aging is the availability to evaluate bloodstain aging at different temperatures

Summary

Introduction

As a cardinal biological system, is a challenging target for biochemical characterization because of sample complexity and a lack of analytical approaches. Multivariate statistical modeling, such as partial least squares and support vector machine, has been applied to time series of Raman scattering, Fourier transform infrared spectroscopy absorption and visible absorption spectra to distinguish new/old bloodstains and predict the time elapsed since deposition[19,20,21,22] These studies demonstrate that spectral changes reflect transformation of the chemical constituents in bloodstains during aging, and these can be mathematically correlated with the elapsed time. This pioneering research has successfully shown the potential of spectroscopic approaches to capture and correlate the changes of chemical components in blood. Development of a model that incorporates the underlying chemistry in bloodstain aging would be beneficial to enhance the availability of bloodstain analysis in forensic investigations

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