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THC-COOH Detected!  ∆-8 or ∆-9?

  • Jamie York
  • #Blogs
  • #Cannabinoïdes
  • #Choix des produits
  • #Colonnes LC Raptor
  • #Développement de méthodes
  • #Colonnes HPLC et UHPLC
  • #Colonnes analytiques
  • #Précolonnes
  • #Etalons de référence
  • #Etalons de référence par secteur
  • #Botanique
  • #Botanique
  • #Cannabis
  • #LC
  • #MS/MS
  • #Optimisation de méthodes
  • #Urine
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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)
Temp.: 30 °C
Sample (±)11-Nor-9-carboxy-D9-THC (cat.# 34068), other compound obtained separately
Diluent: 30/70 Water/Methanol, 0.1% formic acid
Conc.: 2.5 ng/mL
Inj. Vol.: 2 µL
Mobile Phase  
A: Water, 0.1% formic acid
B: Methanol, 0.1% formic acid
Time (min) Flow (mL/min) %A %B
0.00 0.4 30 70
3.5 0.4 30 70
Detector MS/MS
Ion Source: Electrospray
Ion Mode: ESI+
Instrument UHPLC
Peaks tR (min) Conc. (ng/mL) Precursor Ion Product Ion 1 Product Ion 2
Δ-8-THC-COOH 2.842 2.5 345.2 299.3 327.2
Δ-9-THC-COOH 3.237 2.5 345.1 327.1 299.2


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!

Vidéo(s) sur le sujet

Did You Know THC Has Isomers?

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Colonnes LC "core-shell" Raptor FluoroPhenyl (USP L43)

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Pré-colonnes EXP Raptor

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