Analysis of post mortem brain tissue using EMIT.

Area of Science:

• Forensic Toxicology
• Analytical Chemistry
• Neuroscience

Background:

• Enzyme Multiplied Immunoassay Technique (EMIT) is typically used for drug detection in urine and serum.
• Analysis of drugs directly in brain tissue presents challenges due to interfering substances.
• Chromatographic techniques are standard for drug screening in biological samples.

Purpose of the Study:

• To evaluate the utility of EMIT for analyzing drugs in aqueous brain extracts.
• To assess the sensitivity and reliability of EMIT compared to established chromatographic methods.
• To determine the prevalence of positive drug findings in post-mortem brain samples using EMIT.

Main Methods:

• A modified Stas-Otto procedure was employed to extract drugs from brain tissue, creating a clean aqueous solution.
• The prepared aqueous extracts were analyzed using EMIT assays.
• Results were compared with findings from standard chromatographic screening techniques.

Main Results:

• EMIT demonstrated detection limits as sensitive as chromatographic methods for drug analysis in brain extracts.
• Out of 166 cases analyzed, 50 positive drug findings were identified.
• Two glutethimide cases incorrectly tested positive for barbiturates, and one amitriptyline overdose case tested positive for benzodiazepines.
• The majority of positive EMIT findings correlated well with chromatographic results, indicating high specificity.

Conclusions:

• EMIT is a viable and sensitive method for detecting drugs in aqueous brain extracts.
• The modified Stas-Otto procedure effectively removes interfering substances, enhancing EMIT's applicability.
• While generally accurate, potential cross-reactivity (e.g., glutethimide with barbiturates) necessitates careful interpretation and confirmation with chromatographic methods.