Detection of 11-nor-9-carboxy-tetrahydrocannabinol in the hair of drug abusers by LC–MS/MS analysis. (February 2019)

• Record Type: Journal Article
• Authors: Cho, Han Soo; Cho, Byungseok; Sim, Juhyun; Baeck, Seung Kyung; In, Sangwhan; Kim, Eunmi
• Is Part Of: Forensic science international. Volume 295(2019)
• Page Start: 219
• Page End: 225
• Publication Date: 2019-02
• Subjects: 11-Nor-9-carboxy-tetrahydrocannabinol -- Hair analysis -- LC–MS/MS; Medical jurisprudence -- Periodicals; Chemistry, Forensic -- Periodicals; Forensic Medicine -- Periodicals; Médecine légale -- Périodiques; Chimie légale -- Périodiques; Gerechtelijke geneeskunde; Gerechtelijke chemie; Gerechtelijke psychiatrie; Chemistry, Forensic; Medical jurisprudence; Electronic journals; Periodicals; Electronic journals; 614.1
• DOI: 10.1016/j.forsciint.2018.12.013
• Languages: English
• ISSNs: 0379-0738

Abstract

Highlights: A LC–MS/MS method for the detection of THC-COOH in the hair was developed. This method was validated and successfully applied to the analysis of authentic hair samples. The distribution of THC-COOH in the hair of Korean drug abusers in 2017 was investigated. This method showed the possibility of replacing the existing GC–MS/MS analysis. Abstract: Cannabis is the second most commonly abused illicit drug after methamphetamine in South Korea. To prove cannabis consumption, 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH), the metabolite of tetrahydrocannabinol (THC), was screened for in a hair analysis. In this study, we developed a liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis method, which was used to analyze authentic hair samples in 2017. Possible contaminants on the surface of hair samples were eliminated by washing twice each with 2 mL of methanol and distilled water. After adding an internal standard (THC-COOH-d3 ), the hair samples (about 20 mg each) were digested with 1 M NaOH, extracted twice with mixed organic solvents ( n -hexane:ethyl acetate), and analyzed by an LC–MS/MS system. Identification and quantification of THC-COOH and THC-COOH-d3 were performed using a multiple reaction monitoring (MRM) mode at m/z 245 and 191 and m/z 248, respectively (quantifier ions are underlined). The following validation parameters were evaluated: selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, matrix effect, and recovery. The LOD and LOQ of the method was 0.1 pg/mg. Good linearity was achieved for THC-COOH in the range from 0.1 to 20 pg/mg. The method showed an acceptable precision and accuracy, both of which were less than 15% at the three concentrations of THC-COOH (0.2, 1, and 10 pg/mg). THC-COOH showed ion suppression at these three concentrations. The concentrations of THC-COOH in the authentic hair samples ranged from 0.10 to 27.30 pg/mg (total 586 cases), and its concentrations were classified as low, medium, or high ranges, i.e., 0.10–0.39 pg/mg, 0.39–1.99 pg/mg, or 1.99–27.30 pg/mg, respectively, according to statistical evaluation. This method showed the possibility of replacing the existing gas chromatography-tandem mass spectrometry (GC–MS/MS) analysis. However, further development of our LC–MS/MS method is necessary in order to meet the recommended 0.05 pg/mg cut-off.