Can Post-Mortem Cartilage Reliably Preserve Ethanol? A Time-Course Comparison with Blood and Urine

The time interval between the collection of biological material and the performance of toxicological analyses is particularly important when the appropriate storage temperature cannot be maintained. This issue is especially relevant in the determination of ethanol concentration in specimens obtained from drivers suspected of intoxication or being under the influence of ethanol, as well as in samples collected during post-mortem examinations. The present study evaluated the effect of room-temperature storage on ethanol concentrations in post-mortem blood, urine, costal cartilage, and intervertebral disc cartilage collected from 57 cadavers. According to Polish law, blood ethanol concentrations > 0.2 mg/mL and >0.5 mg/mL were classified as “after alcohol use” and “intoxication”, respectively. Two subgroups were therefore distinguished from the study group: 27 ethanol-positive > 0.5 mg/mL (intoxicated) and 30 ethanol-negative cases—less than or equal to 0.5 mg/mL (sober). Ethanol concentrations were determined using gas chromatography with flame ionization detection (GC-FID). Statistically significant differences in blood ethanol concentration were observed in ethanol-positive individuals depending on storage time after sample collection (p < 0.001). Under the storage conditions used in this study, no increase in ethanol concentration was observed in samples collected from ethanol-negative individuals. In ethanol-positive individuals, ethanol concentrations decreased progressively in all analyzed matrices during room-temperature storage. Urine showed the greatest stability throughout the observation period. In both cartilage matrices, ethanol was detectable up to day 3, whereas all measurements were negative from day 4 onward. Blood ethanol concentrations also decreased during storage. By day 4, the mean concentration was below the legal intoxication threshold.