Urine testing for cannabis metabolites is a routine analysis for drug testing labs, but what metabolite is actually being observed when a positive result is detected? Cannabis is a very complex matrix composed of many different constituents, some illegal and some legal in the United States. Delta-9-THC is the main psychoactive component in cannabis, but this compound has over 30 different isomeric forms! Some of which are discussed in more detail in the following blog: Analyzing THC Concentrates? Look for Isomers!
For the purpose of this blog, I’ll only be talking about delta-9-THC and delta-8-THC. Delta-9-THC is illegal for recreational use in most states but the legality of it is growing. Delta-8-THC, which has some diluted psychoactive effects, is legal on a federal level but has been banned in a few states.
So what happens when delta-8-THC is ingested and a urine screen for delta-9-THC is performed? The metabolites for delta-8-THC and delta-9-THC are structurally similar isobars and are only differentiated by the location of a singular double bond. Both compounds will produce a carboxylated metabolite requiring chromatographic separation in order to differentiate between the two isomers which may not occur in most routine testing methods.
Here, a method has been developed to detect delta-9-THC-COOH (11-nor-9-carboxy-9-THC) and delta-8-THC-COOH (11-nor-9-carboxy-8-THC) in 3.5 mins by LC-MS/MS. This method utilizes isocratic mobile phase conditions for high throughput, has simple mobile phase additives, and produces baseline resolution.
|Column||Raptor FluoroPhenyl (cat.# 9319A12)|
|Dimensions:||100 mm x 2.1 mm ID|
|Particle Size:||2.7 µm|
|Pore Size:||90 Å|
|Guard Column:||Raptor FluoroPhenyl EXP Guard Column Cartridge 5 mm, 2.1 mm ID, 2.7 µm (cat.# 9319A0252)|
|Sample||(±)11-Nor-9-carboxy-D9-THC (cat.# 34068), other compound obtained separately|
|Diluent:||30/70 Water/Methanol, 0.1% formic acid|
|Inj. Vol.:||2 µL|
|A:||Water, 0.1% formic acid|
|B:||Methanol, 0.1% formic acid|
|Peaks||tR (min)||Conc. (ng/mL)||Precursor Ion||Product Ion 1||Product Ion 2|
By using this method of analysis, drug testing labs are able to resolve the two metabolite isomers with a 3.5 minute cycle time, allowing for rapid differentiation between the two compounds. Is your lab currently running or interested in this analysis? Let us know about it in the comments below!