Validated Matrix Matched Quantification of Ethyl Chloride in Postmortem Biological Samples Using HS-GC-FID: Lung as the Optimal Tissue and Temporal Detection Dynamics

Ethyl chloride, a volatile anesthetic with high abuse potential, remains forensically undercharacterized postmortem. In an inhalation model (n = 30), male Wistar rats were exposed to 86,000 ppm ethyl chloride under real-time PID monitoring; blood, lung, liver and brain (plus exploratory adipose, kidney, muscle) were sampled at 0, 2, 4, 6 and 12 h postmortem. A matrix-matched HS-GC-FID method was validated (Eurochem): linearity (R2 = 0.9947–0.9965), LOD 0.01–0.02 ng/μL, LOQ 0.04–0.06 ng/μL, precision RSD 3.9–5.1%, recovery 90–104%, full selectivity against common volatiles. Lung yielded the highest concentrations overall; a significant decline occurred in lung between 2 h and 4 h (Pillai’s Trace p = 0.034). Concentrations became increasingly irregular ≥6 h across tissues. Early autopsy sampling, preferably within ≤6 h, optimizes ethyl chloride detectability. The validated matrix-matched HS-GC-FID protocol provides a cost-effective, robust alternative to MS platforms for volatile screening in routine forensic practice and supports prioritizing lung for analysis.