The Determination of Cannabinoids in Urine Samples Using Microextraction by Packed Sorbent and Gas Chromatography-Mass Spectrometry

Abstract

Cannabis is the most consumed illicit drug worldwide, and its legal status is a source of concern. This study proposes a rapid procedure for the simultaneous quantification of Δ9-tetrahydrocannabinol (THC), 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC), 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH), cannabidiol (CBD), and cannabinol (CBN) in urine samples. Microextraction by packed sorbent (MEPS) was used to pre-concentrate the analytes, which were detected by gas chromatography–mass spectrometry. The procedure was previously optimized, and the final conditions were: conditioning with 50 µL methanol and 50 µL of water, sample load with two draw–eject cycles, and washing with 310 µL of 0.1% formic acid in water with 5% isopropanol; the elution was made with 35 µL of 0.1% ammonium hydroxide in methanol. This fast extraction procedure allowed quantification in the ranges of 1–400 ng/mL for THC and CBD, 5–400 ng/mL for CBN and 11-OH-THC, and 10–400 ng/mL for THC-COOH with coefficients of determination higher than 0.99. The limits of quantification and detection were between 1 and 10 ng/mL using 0.25 mL of sample. The extraction efficiencies varied between 26 and 85%. This analytical method is the first allowing the for determination of cannabinoids in urine samples using MEPS, a fast, simple, and low-cost alternative to conventional techniques.

Analysis of Cannabinoids in Biological Specimens: An Update

“…The THC-COOH-gluc:THC-COOH ratio varies from around 1.3 to 4.5, so monitorization of THC-COOH-gluc is often deemed necessary [38]. Another possibility of detecting the metabolites is via sample alkaline digestion [58].…”

“…Rosendo et al [58] were the first team to extract THC, THC-OH, THC-COOH, CBN, and CBD from urine samples using a microextraction by packed sorbent (MEPS) technique to pre-concentrate the compounds, which were later analysed by GC-MS. The method was applied successfully to authentic samples and proved efficient.…”

Analytical techniques for screening of cannabis and derivatives from human hair specimens

“…Gas chromatography-mass spectrometry (GC-MS) is a standard methodology for detection of drugs of abuse, specifically for detecting the presence of THC and its metabolites in the hair samples. 88 However, GC-MS is associated with some disadvantages. The technique demands derivatization of drugs and metabolites before injecting them into the GC-MS column.…”

Green chemistry: Developments and perspectives for sample treatment in forensic methodologies

“…Another major benefit of MEPS is the possibility to automate the entire process by using semi‐automatic syringes or autosamplers, this allows for the direct injection of the extracted compounds directly into the analytical system. Variables such as the number of cycles in each extraction stage and the elution speed in the syringe can significantly influence the analytical response, therefore the evaluation of these parameters is recommended (Da Cunha et al, 2020; Rosendo et al, 2022).…”