Estimation of Postmortem Interval in Rat Liver and Spleen Using Fourier Transform Infrared Spectroscopy

Abstract

The aim of this study was to investigate the changes of Fourier transform infrared (FT-IR) spectra of rat liver and spleen tissues from time zero to 144 h postmortem. The absorbance (Ax represents the infrared absorbance at wavenumber x cm−1) ratios of major absorbance bands were examined. A 3303/A 2925, A 1647/A 1541 (liver), A 1238/A 1338, A 1153/A 1338 (liver), A 1080/A 1338, and A 1030–1050/A 1338 (liver) showed a decrease postmortem, whereas the A 1396/A 1456 ratio (spleen) showed an increase. Furthermore, these absorbance ratios showed a strong linear relationship with increasing time postmortem, and the A 1238/A 1338 ratio of spleen offered a stronger correlation (R 2 = 0.88) than did the others. A new absorbance band appeared at 1120 cm−1 for the liver and spleen at 120 h postmortem and another new band appeared at 1170 cm−1 for the liver, but the existing absorbance band at 1170 cm−1 disappeared in the spleen. Our initial results demonstrate that the quantitative analysis of FT-IR spectrum related to postmortem interval (PMI) shows a strong linear correlation between absorbance ratios and increasing time after death. The FT-IR changes of spectra and absorbance ratios can support further study for estimating short-term and long-term PMI. Upon future validation, FT-IR can offer advantages in combination with established methods to improve PMI estimation.