Targeted metabolomics of postmortem human cardiac tissue using the Biocrates MxP Quant 500 kit

Aim: This proof-of-concept study aimed to evaluate the feasibility and analytical performance of the Biocrates MxP® Quant 500 kit, originally developed for biofluids, to postmortem human cardiac tissue obtained from forensic autopsies, evaluating its potential as a standardized, cost-effective alternative to complex, resource-intensive metabolomics workflows. Methods: Left ventricular tissue samples were collected from 40 forensic autopsy cases, comprising 10 decedents with type 2 diabetes, 20 decedents with ischemic heart disease without type 2 diabetes, and 10 control cases without cardiac pathology. Cases were selected to represent the range of myocardial conditions commonly encountered in forensic practice, enabling assessment of analytical feasibility across heterogeneous postmortem cardiac tissue. Samples were analyzed using the MxP® Quant 500 kit following the standard protocol and using liquid chromatography–tandem mass spectrometry and flow injection analysis methods, measuring and quantifying a total of 630 endogenous metabolites across diverse classes. Results: Out of the 630 metabolites, 463 (74%) were within the quantifiable range. Lipid-related metabolites were notably well represented, with sphingomyelins (100% retained), phosphatidylcholines (93% retained), triacylglycerols (82% retained), and fatty acids (83% retained) showing the highest retention. Other metabolite classes such as acylcarnitines (45% retained) demonstrated greater variability, with some measurements falling below the limit of detection (e.g., 47% of acylcarnitines below this limit) or exceeding the upper limit of quantification (e.g., 35% of amino acids above this limit). Univariate analyses showed nominal group differences among specific metabolite subclasses (unadjusted p