Cannabinoid Stability in Postmortem Brain Samples Stored at Different Temperatures.

Area of Science:

• Forensic Toxicology
• Pharmacology
• Analytical Chemistry

Background:

• Drug stability in postmortem samples is critical for accurate forensic toxicological testing.
• Degradation of analytes over time can significantly affect the interpretation of toxicological results and casework outcomes.
• The brain is a valuable matrix for xenobiotic analysis in postmortem investigations.

Purpose of the Study:

• To assess the stability of key cannabinoids, including ∆9-tetrahydrocannabinol (THC), in postmortem brain tissue.
• To determine optimal storage conditions (4°C, -20°C, -70°C) for preserving cannabinoid integrity for up to 12 months.
• To evaluate the impact of storage temperature on the stability of THC and its major metabolites.

Main Methods:

• Pooled brain specimens were spiked with cannabinoids at varying concentrations.
• Samples were stored at 4°C, -20°C, and -70°C for up to 390 days.
• Analyte concentrations were quantified over time to assess degradation, with stability defined as within ±20% of the initial concentration.

Main Results:

• All studied cannabinoids demonstrated stability in frozen brain samples (-20°C and -70°C) for over 12 months.
• Analyte concentrations remained within ±20% of the target concentration in frozen samples.
• Under refrigeration (4°C), 11-hydroxy-THC (11-OH-THC), THCCOOH, and THCCOOH-glucuronide showed instability.

Conclusions:

• Frozen storage at -20°C or -70°C is recommended for preserving cannabinoid stability in postmortem brain samples for extended periods.
• Refrigeration at 4°C is unsuitable for long-term storage of brain samples containing these cannabinoids due to degradation.
• The brain is a reliable matrix for postmortem toxicological analysis, even after prolonged storage under appropriate conditions.