The sudden increase in states legalizing marijuana has forced law enforcement into a situation where the use and consumption are legal, but there are no limitations for what is acceptable for driving or operating machinery. Using ultraviolet–visible (UV–vis) spectroscopy, fingerprints from volunteers who had used marijuana were analyzed via a competitive immunoassay for the detection of Δ9-tetrahydrocannabinol (Δ9-THC), the main psychoactive component of marijuana, and 11-nor-9-carboxy-THC (THC-COOH), one of the main metabolites produced in the body following the use/consumption of THC-related products. In this research, the THC-COOH metabolite and the enzyme-labeled conjugate compete against each other as the antigens for the system. The antibody used in this assay has a greater affinity for the metabolite; so, as its concentration increases, the absorbance of the system decreases due to less binding of the enzyme-labeled conjugate.
(Publisher abstract provided.)