Simultaneous determination of Δ9-tetrahydrocannabinol and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol in oral fluid using isotope dilution liquid chromatography tandem mass spectrometry

Abstract

The detection and confirmation of cannabinoids in oral fluid are important in forensic toxicology. Currently, the presence of Δ(9)-tetrahydrocannabinol (THC) is used for the detection of cannabis in oral fluid. A low concentration of 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol (THC-COOH) is found in oral fluid, which suggested a convenient and low-sensitivity confirmation assay can be used in a routine forensic laboratory. In this study, a highly sensitive isotope dilution liquid chromatography-tandem mass spectrometry method following dansylation was successfully developed for simultaneous determination of THC and THC-COOH in oral fluid. The dansylated derivatives dramatically demonstrated and enhanced the sensitivity of THC and THC-COOH. To avoid signal influenced by the matrix, a 5-min liquid chromatography gradient program was evaluated and optimized, which reduced the sample diffusion and caused sharp peaks (less than 12 s) and thus helped to achieve detection at a low level. The sensitivity, accuracy, and precision were also evaluated, and high quantitative accuracy and precision were obtained. The limit of quantitation of this approach was 25 pg/mL for THC and 10 pg/mL for THC-COOH in oral fluid. Finally, the method was successfully applied to eight suspected cannabis users. Among them, in six oral fluid samples THC-COOH was determined at a concentration from 13.1 to 47.2 pg/mL.

11-Nor-9-carboxy-∆9-tetrahydrocannabinol quantification in human oral fluid by liquid chromatography–tandem mass spectrometry

“…recently reported a LCMSMS method for THCCOOH in a Quantisal-collected oral fluid with a specimen volume equivalent to 250 μL oral fluid, similar to our current method, employing solid phase extraction prior to derivatization with triphenylphosphine and 2-picolylamine prior to LC triple quadrupole MS achieving a 10 pg/mL LOQ [21]. Our current LCMSMS method achieves similar LOQs with identical oral fluid specimen volumes while avoiding costly derivatization required for these other two LCMSMS methods [21, 22]. …”

“…Lee et al reported a LCMSMS method for THCCOOH in 250 μL expectorated oral fluid that employed acetonitrile precipitation, derivatization with dansyl chloride, and liquid-liquid extraction prior to LC triple quadrupole MS achieving an LOQ of 5 pg/mL [22]. Coulter et al.…”

“…Lee et al and Coulter et al employed chemical derivatization with dansyl chloride or triphenylphosphine and 2-picolylamine, respectively, prior to LCMSMS, achieving oral fluid limits of quantification (LOQ) of 5 and 10 pg/mL, respectively [21, 22]. He et al employed drydown, reconstitution, and ultrafiltration (DRUF) prior to online trapping and microflow liquid chromatography with high-resolution Orbitrap MS achieving a THCCOOH LOQ of 7.5 pg/mL [23].…”

Current knowledge on cannabinoids in oral fluid

“…Another 2-dimensional GC-MS assay was the first to quantify OF THCCOOH (LOQ = 7.5 ng/L) as well as THC, CBD, CBN, and 11-OH-THC (LOQs = 0.5-1 μg/L). [215] In the past year, LC-MSMS, [186, 216] microflow LC-MSMS, [217-218] and isotope dilution LC-MSMS [219] methods to analyze OF for THCCOOH (LOQs = 7.5-15 ng/L) and THC (0.25-1 μg/L) were published. Chromatographic OF confirmation assays for cannabinoids published since 2003 are described in Table 6.…”

Oral Fluid for The Detection of Drugs of Abuse Using Immunoassay and LC–MS/MS

“…More recently, methods have been published using LC-MS/MS requiring derivatization, usually unnecessary in LC-MS/MS procedures. Lee et al reported the derivatization of THC and THC-COOH with dansyl chloride to improve sensitivity for detection in OF [53]; and Coulter et al derivatized with 2-picolylamine in the presence of triphenylphosphine to form a derivative for improved sensitivity (LOQ 0.01 ng/ml) [54]. Other methods are currently being developed and the future is certainly the simultaneous detection of THC and THC-COOH in OF using routine LC-MS/MS methods.…”