Homogeneous enzyme immunoassay for cannabinoids in urine

Area of Science:

• Forensic Toxicology
• Biochemistry

Background:

• Cannabinoid use is prevalent, necessitating reliable detection methods.
• Existing assays may have limitations in sensitivity or specificity for cannabinoid metabolites.
• Accurate measurement of delta9-tetrahydrocannabinol and its metabolites is crucial for both clinical and forensic applications.

Purpose of the Study:

• To develop and validate a homogeneous enzyme immunoassay for quantifying cannabinoid metabolites and delta9-tetrahydrocannabinol in urine.
• To establish the assay's sensitivity, specificity, and cutoff concentration for detecting cannabinoid use.
• To differentiate between cannabinoid use and intoxication based on metabolite detection.

Main Methods:

• A homogeneous enzyme immunoassay was developed.
• Malate dehydrogenase was labeled with a delta9-tetrahydrocannabinol derivative.
• The assay was calibrated using 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid as the standard.
• Urine samples were analyzed for cannabinoid metabolites.

Main Results:

• The assay demonstrated reliable detection of cannabinoid metabolites and delta9-tetrahydrocannabinol.
• A cutoff concentration of 15 µg/L of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid was established.
• The assay could detect 25 µg/L of the metabolite with >95% confidence.
• Positive results were observed within 30 minutes of cannabinoid exposure.

Conclusions:

• The developed immunoassay is a sensitive tool for detecting cannabinoid metabolites in urine.
• Urine analysis is a valuable indicator of cannabinoid use due to metabolite persistence.
• The assay is not suitable for determining the level of cannabinoid intoxication.