A Study on the Estimation of Postmortem Interval Based on Environmental Temperature and Concentrations of Substance in Vitreous Humor

A method to determine postmortem interval ( PMI ) based on environmental temperature and the concentrations of vitreous humor ( VH ) molecules were explored. Rabbit carcasses were placed in a chamber at 5, 15, 25, or 35°C, and 80–100 μL of VH was collected with the double‐eye alternating micro‐sampling method every 12 h. A Roche DPPI biochemical analyzer was used to measure the concentrations of six substances in VH samples. The interpolation function model and mixed‐effect model were employed for data fitting to establish equations for PMI estimation. The concentrations of K + , P, Mg 2+ , creatinine (CRE), and urea nitrogen (UN) exhibited an upward trend with increasing PMI in all temperature groups, while the concentration of Ca 2+ showed a downward trend. Validation results using K + and Mg 2+ ions revealed that the mixed‐effect model provided a better estimation than the interpolation function model using the data from our experiment. However, both models were able to estimate PMI using temperature and VH molecule concentrations.