Using sweeping micellar electrokinetic chromatography to analyze Δ⁹-tetrahydrocannabinol and its major metabolites

• Published in: Journal of Chromatography A Vol. 1216; no. 16; pp. 3512 - 3517
• Main Authors: Su, Hsiu-Li, Feng, Lan-Ing, Jen, Hsiu-Ping, Hsieh, You-Zung
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Amsterdam; New York: Elsevier 01.04.2009; Elsevier
• Subjects: Biological and medical sciences; Drug addictions; Medical sciences; Toxicology; Trace analysis; Human; Urine; Solid phase extraction; Biological fluid; Terpenoid; Chemical analysis; Δ9-Tetrahydrocannabinol; Metabolite; Psychotropic; Micellar electrokinetic capillary chromatography; Elimination; On-line preconcentration; Cannabinoid; Micellar electrokinetic chromatography; Chemical enrichment; Sample preparation; Simultaneous measurement; Drug of abuse; Sweeping-MEKC; Quantitative analysis
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2008.10.004

We have applied sweeping micellar electrokinetic chromatography (sweeping-MEKC) to the simultaneous determination of Δ⁹-tetrahydrocannabinol (THC) and its major metabolites, 11-hydroxy-Δ⁹-tetrahydrocannabinol (THC-OH) and 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (THC-COOH). We monitored the effects of several of the sweeping-MEKC parameters, including the proportion of organic modifier, the concentration of sodium dodecyl sulfate (SDS), the pH, and the sample injection volume, to optimize the separation process. The optimal buffer for the analysis of the three analytes was 25mM citric acid/disodium hydrogenphosphate (pH 2.6) containing 40% methanol and 75mM SDS. Under the optimized separation parameters, the enrichment factors for THC, THC-COOH, and THC-OH when using sweeping-MEKC (relative to MEKC) were 77, 139, and 200, respectively. The limits of detection (LODs) for the three compounds in standard solutions ranged from 3.87 to 15.2ng/mL. We combined the sweeping-MEKC method with solid-phase extraction to successfully detect THC, THC-COOH, and THC-OH in human urine with acceptable repeatability. The LODs of these analytes in urine samples ranged from 17.2 to 23.3ng/mL. Therefore, this sweeping-MEKC method is useful for determining, with high sensitivity, the amounts of THC and its metabolites in the urine of suspected THC users.