Linearization of the relationship between postmortem plasma chloride concentration and postmortem interval in rats

Area of Science:

• Forensic Science
• Biochemistry
• Physiology

Background:

• Accurate estimation of postmortem interval (PMI) is crucial in forensic investigations.
• Plasma chloride concentration (PCl) changes predictably after death.
• Previous studies have explored various biomarkers for PMI estimation.

Purpose of the Study:

• To investigate the utility of plasma chloride concentration (PCl) changes for estimating the postmortem interval (PMI) in rats.
• To establish a quantitative relationship between PCl and PMI in rats.
• To compare rat PCl changes with those observed in humans and dogs.

Main Methods:

• A potentiometric titration procedure was utilized to measure PCl in rat plasma.
• Blood samples were collected at regular intervals over a 96-hour postmortem period.
• Data were analyzed using double logarithmic plots to assess the relationship between PCl and PMI.

Main Results:

• Plasma chloride concentration (PCl) exhibited a consistent rate of decrease postmortem in rats.
• The observed PCl decrease patterns in rats were comparable to those in dogs and humans.
• A strong linear correlation (r = -0.97, P < 0.001) was found between PCl and PMI on a double logarithmic plot.

Conclusions:

• The rate of change in plasma chloride concentration (PCl) can serve as a reliable indicator for estimating the postmortem interval (PMI).
• The findings in rats support the potential application of PCl analysis in forensic science for time since death estimation.
• Further research may validate this method across diverse conditions and species.