In vitro β-hydroxybutyrate stability evaluation in femoral blood and vitreous humor for integration into forensic toxicology practices

Thanatological biochemistry has gained prominence in determining causes of death, especially when suspected fatal pathologies do not exhibit clear postmortem macroscopic and/or microscopic features, such as in cases of ketoacidosis. Indeed, in these cases, the measurement of β-hydroxybutyrate (BHB) in femoral blood and/or vitreous humor is of particular importance. However, data on its in vitro stability remain scarce, especially in vitreous humor. In this context, the study reported here aims to assess the in vitro stability of BHB. BHB quantification was performed using a liquid chromatography coupled with tandem mass spectrometry method. To investigate BHB stability, two different postmortem matrices were considered: femoral blood and vitreous humor. These matrices were pooled, aliquoted and spiked with BHB at three different concentrations (50 mg/L, 100 mg/L, and 200 mg/L; n = 3). Initial BHB concentrations were established on day 1. Each sample was then divided into two aliquots for storage under two conditions: 20 °C and 4 °C. Analyses were performed on Day 3, 7, 14, and 28. The study revealed no significant degradation of BHB in femoral blood or vitreous humor over time (days 1-28), confirming the robustness and reliability of BHB measurement in these matrices as a postmortem biomarker of ketoacidosis under the tested temperature conditions (+4 °C or -20 °C). These results support a systematic integration of BHB measurement into the routine workflow of forensic toxicology laboratories.