Estimation of the postmortem interval using chromatographic fingerprints of volatile organic compounds from muscle

Estimation of the postmortem interval (PMI) is a crucial task in the field of forensic pathology and has unfortunately not been properly resolved. In this study, we analyzed volatile organic compounds (VOCs) in rat muscle samples collected at different PMIs and studied the feasibility of muscle VOC fingerprinting as a new method for PMI estimation. In total, 110 rats were sacrificed and stored at a constant temperature (25°C). Rat skeletal muscle samples were collected at 0–10-day postmortem, and then the VOCs were determined using a method of headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. The correlations between the VOCs (species and quantities) and PMIs were carefully analyzed and standard muscle VOC fingerprints at 25°C were established for different PMIs. To further test the accuracy of muscle VOC fingerprinting as a method for PMI estimation, ten additional rats with known PMIs were studied. We identified 15 kinds of VOCs and the number of VOC species increased with the PMI. The total peak areas of the VOCs increased significantly with the postmortem day (adjusted R2 = 0.96–0.97). The mean error of the VOC fingerprinting for PMI estimation was 0.5 days and the mean relative error was 8.33%. We concluded that muscle VOC fingerprinting combining the use of VOC species and peak areas is accurate and effective and could be used as an alternative approach for PMI estimation in forensic practice. Although the preliminary results are encouraging, further studies in human cadavers under real case conditions are needed