Abstract: Objective To explore the relationship between the change rules of volatile organic compounds （VOCs） in rat muscle and postmortem interval （PMI）. Methods A total of 120 healthy rats were divided randomly into 12 groups （10 for each group）. After the rats were sacrificed by cervical dislocation, the bodies were kept at （25±1） ℃. Rat muscle samples were separately obtained at 12 PMI points, including 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 d. The VOCs in rat muscles were collected, detected and analyzed by headspace solid-phase microextraction （HS-SPME） coupled to gas chromatography-mass spectrometer （GC-MS）. Results In total, 15 species of VOCs were identified, including 9 aromatic compounds, 3 sulfur compounds, 2 aliphatic acids and 1 heterocyclic compound. The species of VOCs increased with PMI： no species were detected within 1 day, 3 species were detected on day 2, 9 on day 3, 11 on day 4, 14 from day 5 to 7, and 15 from day 8 to 10. Total peak area of 15 species of VOCs was significantly correlated to PMI （adjusted R2=0.15-0.96）： the regression function was y=-17.05 x2+ 164.36 x-246.36 （adjusted R2=0.96） from day 2 to 5, and y=2.24 x+101.13 （adjusted R2=0.97） from day 6 to 10. Conclusion The change rules of VOCs in rat muscle are helpful for PMI estimation.

Key words: forensic pathology, volatile organic compounds, gas chromatography-mass spectrometry, solid phase microextraction, postmortem interval, muscles, rats