PMI estimation through ¹H NMR metabolomics on human pericardial fluid: a validation study

Area of Science:

• Forensic Science
• Biochemistry
• Analytical Chemistry

Background:

• Post-mortem interval (PMI) estimation is crucial in forensic investigations.
• Previous proof-of-concept studies indicated metabolomic analysis of pericardial fluid's potential for PMI estimation.
• The reproducibility and utility of this method require further validation.

Purpose of the Study:

• To assess the reproducibility of metabolomic analysis of post-mortem pericardial fluid.
• To validate the utility of pericardial fluid metabolomics for estimating the post-mortem interval.
• To identify key metabolites predictive of the post-mortem interval.

Main Methods:

• Collected 65 pericardial fluid samples from medico-legal autopsies with post-mortem intervals ranging from 16 to 199 hours.
• Performed liquid-liquid extraction and 1H NMR analysis to quantify 50 metabolites.
• Utilized multivariate statistical analyses to develop and validate post-mortem interval estimation models, controlling for age.

Main Results:

• Confirmed high reproducibility (92% similarity) of metabolite quantification in re-analyzed samples.
• Developed regression models for PMI estimation with prediction errors of 16.7h (16-100h), 23.2h (16-130h), and 42.1h (16-199h).
• Identified key predictive metabolites including choline, glycine, citrate, and others; a classification model accurately detected intervals >48h.

Conclusions:

• Metabolomic analysis of pericardial fluid is stable and reproducible, demonstrating robust intra-laboratory consistency.
• Pericardial fluid metabolomics is a promising, reliable forensic tool for post-mortem interval estimation.
• The method is particularly valuable for estimating longer post-mortem intervals (>48 hours).