Serum and Urine Quantification of Delta-8 and Delta-9 Tetrahydrocannabinol Carboxylic Acid Using Gas Chromatography-Mass Spectrometry

Marijuana is one of the most frequently used drugs in the United States. The major psychoactive ingredient of the marijuana plant is delta-9-tetrahydrocannabinol (Δ9-THC) with delta-8-tetrahydrocannabinol (Δ8-THC) also being a minor psychoactive ingredient. Marijuana has several clinical applications, but it is more notably used for recreational purposes. Δ8-THC elicits similar but diminished psychotropic effects to Δ9-THC, and the popularity of consuming synthetically produced Δ8-THC is on the rise. The use of Δ9-THC and Δ8-THC has varying degrees of legality depending on one’s location; thus it is important to distinguish between the two isomers. Both compounds are metabolized in humans to their corresponding carboxylic acids and then undergo glucuronidation. This method describes how to separate and quantify Δ9-THC-COOH and Δ8-THC-COOH in serum or urine using gas chromatography-mass spectrometry (GC-MS) and a deuterated internal standard.