J. Beck and C. Schmidt, Varian, Inc.
Marijuana is one of the most commonly used illegal recreational drugs in the United States. The compound that gives the high from smoking marijuana is tetrahydrocannabinol or THC. Toxicology, forensic, and clinical labs are often asked to analyze urine samples for the presence of one of the metabolites of THC, most frequently the carboxy form.
Traditionally, samples are screened for THC metabolites by immunoassay and confirmed using GC/MS. GC/MS, while the current standard for THC metabolite testing, requires time consuming sample derivatization prior to analysis. LC/MS provides the same specificity and sensitivity without the need for a derivatization process.
A simple, high throughput LC/MS/MS method is described here for the detection and quantitation of ()-11-nor-9-carboxydelta- 9-THC in urine.
Varian ProStar 410 AutoSampler
Varian ProStar 210 Solvent Delivery Modules
Varian 1200L LC/MS/MS equipped with ESI source
Materials and Reagents
Standard solution: 0.1 mg/mL ()-11-Nor-9-Carboxy-Delta- 9-THC (Catalog No. T-006), from Cerilliant Corp., Texas, USA.
Internal standard (IS) solution: 500 ng/mL ()-11-Nor-9- Carboxy-Delta-9-THC-d9 in methanol, a gift from Norchem Drug Testing, Flagstaff, AZ.
Test samples: samples containing various amounts of ()-11- Nor-9-Carboxy-Delta-9-THC, also gifts from Norchem Drug Testing, Flagstaff, AZ.
All other chemicals are reagent grade or HPLC grade.
Serial dilutions of the standard solution of carboxy-THC (THCC) were prepared in deionized water. The concentrations of the samples ranged from 1 ng/mL (1 ppb) to 1000 ng/mL. A 50 μL