Dr. A.P.J. Abdul Kalam Institute of Forensic Science & Criminology, Bundelkhand University, Jhansi, 284128, Uttar Pradesh, India.
DFS, Himachal Pradesh, Junga, Shimla, 171218, Himachal Pradesh, India.
Sci Rep. 2021 Jun 4;11(1):11855. doi: 10.1038/s41598-021-91009-5.
The ex-vivo biochemical changes of different body fluids also referred as aging of fluids are potential marker for the estimation of Time since deposition. Infrared spectroscopy has great potential to reveal the biochemical changes in these fluids as previously reported by several researchers. The present study is focused to analyze the spectral changes in the ATR-FTIR spectra of three body fluids, commonly encountered in violent crimes i.e., semen, saliva, and urine as they dry out. The whole analytical timeline is divided into relatively slow phase I due to the major contribution of water and faster Phase II due to significant evaporation of water. Two spectral regions i.e., 3200-3400 cm and 1600-1000 cm are the major contributors to the spectra of these fluids. Several peaks in the spectral region between 1600 and 1000 cm showed highly significant regression equation with a higher coefficient of determination values in Phase II in contrary to the slow passing Phase I. Principal component and Partial Least Square Regression analysis are the two chemometric tool used to estimate the time since deposition of the aforesaid fluids as they dry out. Additionally, this study potentially estimates the time since deposition of an offense from the aging of the body fluids at the early stages after its occurrence as well as works as the precursor for further studies on an extended timeframe.
不同体液的体外生化变化也称为体液老化，是估计沉积时间的潜在标志物。如先前几位研究人员所报道的那样，红外光谱技术具有揭示这些体液生化变化的巨大潜力。本研究专注于分析三种常见于暴力犯罪中的体液（精液、唾液和尿液）在干燥过程中 ATR-FTIR 光谱的光谱变化。整个分析时间线分为相对较慢的第一阶段，主要是由于水的大量存在，以及更快的第二阶段，主要是由于水的大量蒸发。两个光谱区域，即 3200-3400 cm 和 1600-1000 cm，是这些流体光谱的主要贡献者。在光谱区域 1600 到 1000 cm 之间的几个峰在第二阶段与较高的决定系数值表现出高度显著的回归方程，与缓慢的第一阶段相反。主成分和偏最小二乘回归分析是两种用于估计上述体液干燥过程中沉积时间的化学计量工具。此外，这项研究还可以从犯罪发生后早期的体液老化来潜在地估计犯罪发生的时间，并且可以作为进一步在更长时间范围内进行研究的前奏。
