Testing human blood for cannabis by GC-MS

Area of Science:

• Forensic Toxicology
• Analytical Chemistry

Background:

• Accurate quantification of cannabis compounds in biological matrices is crucial for clinical and forensic applications.
• Existing methods for delta 9-tetrahydrocannabinol (THC) and its metabolite 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THC-COOH) in whole blood may require optimization for sensitivity and efficiency.

Purpose of the Study:

• To develop and validate a sensitive method for the simultaneous determination of THC and THC-COOH in human whole blood.
• To establish reliable quantification limits for these cannabinoids using gas chromatography-mass spectrometry (GC-MS).

Main Methods:

• A 2 mL whole blood specimen was acidified and extracted using hexane:ethyl acetate with deuterated internal standards.
• The extracted compounds were derivatized via methylation using iodomethane and tetrabutylammonium hydroxide-dimethyl sulphoxide (DMSO).
• Derivatives were analyzed by GC-MS after extraction into isoocatane.

Main Results:

• The method achieved a limit of quantification of 1.0 ng/mL for delta 9-tetrahydrocannabinol (THC).
• The limit of quantification for 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THC-COOH) was determined to be 0.5 ng/mL.
• The developed procedure demonstrated effective extraction, derivatization, and sensitive detection of target analytes.

Conclusions:

• This validated GC-MS method provides a robust approach for cannabis testing in human whole blood.
• The established low limits of quantification are suitable for forensic and clinical monitoring of cannabis use.
• The method offers an efficient means for accurate THC and THC-COOH analysis.