Peptide ratios for post-mortem interval estimation using targeted liquid chromatography triple quadrupole mass...

Area of Science:

• Forensic Science
• Biochemistry
• Analytical Chemistry

Background:

• Postmortem interval (PMI) estimation is crucial in forensic investigations but faces challenges, especially in later decomposition stages.
• Current PMI methods have limitations; proteomics offers a more objective approach.
• Previous research identified 19 peptide targets in muscle tissue correlated with decomposition time.

Purpose of the Study:

• To optimize the detection of 19 previously identified peptide targets using a targeted liquid chromatography-triple quadruple mass spectrometry (LC-QQQ) method.
• To assess the reproducibility and applicability of this targeted LC-QQQ method for forensic casework.
• To conduct a longitudinal analysis of peptide targets in authentic human samples over 14 days postmortem.

Main Methods:

• Development and optimization of a targeted LC-QQQ method for 19 specific peptide targets.
• Analysis of human muscle tissue samples over a 14-day postmortem period.
• Data analysis including generation of peptide ratios and log2 transformation.

Main Results:

• 17 out of 19 peptide targets were optimized for reproducible detection.
• The targeted LC-QQQ method yielded interpretable results for most targets over the 14-day period.
• Two previously proposed peptide ratios demonstrated linear trends after data transformation.

Conclusions:

• A targeted LC-QQQ method is a viable system for detecting PMI peptide targets in human postmortem muscle tissue.
• The optimized method shows potential for validation and application in routine forensic casework.
• This proteomics-based approach offers a more objective tool for PMI estimation.