Abstract: Objective To investigate correlation between the changes of oxidation reduction potential （ORP） values of heart blood in rabbits after death and postmortem interval （PMI） at different temperatures. Methods Forty-eight rabbits were randomly divided into 6 groups and sacrificed by air embolism. Blood samples were taken from the right ventricle of each rabbit and stored at different temperatures of 10, 15, 20, 25, 30 and 35 ℃, respectively. Every 4 hours from 0 h to 132 h postmortem, the ORP values of the blood samples were measured at different intervals by PB-21 electrochemical analyzer. The curvilinear regression equation was established by SPSS 17.0 software. The surface equation and 3D surface diagram were established by MATLAB 7.10.0 software. Results The ORP values at different temperatures of heart blood in rabbits were highly correlated with the PMI. The ORP values rised obviously when the temperature was high and rised slowly when the temperature was low. The surface equation and 3D surface diagram were obtained. Conclusion The surface equation and 3D surface diagram of ORP values and PMI may be used for PMI estimation at different temperatures.

Key words: forensic pathology, postmortem interval, oxidation reduction potential, interpolation function, rabbits