GC Analysis of Tetrahydrocannabinol (THC) and Carboxytetrahydrocannabinol (THCCOOH) in Surface Water on SLB®-5ms after SPME using 50/30 μm DVB/Carboxen/PDMS Fiber, On-Fiber Derivatization

GC Analysis of Tetrahydrocannabinol (THC) and Carboxytetrahydrocannabinol (THCCOOH) in Surface Water on SLB®-5ms after SPME using 50/30 μm DVB/Carboxen/PDMS Fiber, On-Fiber Derivatization

Conditions

sample preparation post-extraction derivatization: 500 µL MSTFA in 10 mL vial, headspace, 30 min, 60 °C
sample preparation fiber post-bake: 10 min, 270 °C
sample preparation SPME
sample/matrix 8 mL surface water in 10 mL vial, adjusted to pH 2 with HCl, spiked with THC and THCCOOH at 50 ng/L each compound
desorption process 260 °C, 3 min
extraction immersion, 60 min, 60 °C
SPME fiber StableFlex(TM) SPME Fiber, DVB/CARBOXEN-PDMS, 2 cm
column SLB-5ms: 20 m x 0.18 mm I.D., 0.18 µm (28564-U)
oven 90C (3 min), 20 °C/min to 200 °C, 3 °C/min to 300C (5 min)
carrier gas helium, 1 mL/min constant flow
injection splitless
liner 0.75 mm SPME
inj. temp. 260 °C
detector MSD
MSD interface 325 °C
scan range SIM:THC: m/z=303, 371(quant), 386;THCCOOH: m/z=371 (quant), 473, 488

Description

Analysis Note Cannabis is a Schedule 1 substance under US federal law. However, at the time of this writing, four US states have legalized it for recreational and medical use. The level of use by the general public is typically determined through questionnaires and crime statistics, but this approach may not give an accurate assessment. Sewage epidemiology seeks to correlate data from these surveys with actual levels found in wastewater. In the case of cannabis, this can be done by analyzing for the psychoactive substance, tetrahydrocannabinol (THC), and its major metabolite, carboxytetrahydrocannabinol (THCCOOH). THC can be analyzed by GC directly, but because THCCOOH contains an acid group in its structure it requires derivatization. Thus, if the two compounds are analyzed together, derivatization must be used. In this application, solid phase microextraction (SPME) with post-extraction, on-fiber derivatization was used for low level analysis of THC and THCCOOH from surface water prior to separation on an SLB®-5ms GC column. Cerilliant CRMs provided reliable quantification.
Categories Analytical Chromatography, SPME Applications, GC Applications, Forensics and Toxicology, Drugs of Abuse, Environmental, General Analytical
Featured Industry Environmental
Forensics and Toxicology
Legal Information StableFlex is a trademark of Sigma-Aldrich Co. LLC, SLB is a registered trademark of Sigma-Aldrich Co. LLC
suitability application for SPME, application for GC

Analyte

  • 11-nor-9-Carboxytetrahydrocannabinol (THCCOOH)
  • Tetrahydrocannabinol (THC)

Materials

     
Related Links