Development and validation of a solid-phase extraction method using anion exchange sorbent for the analysis of cannabinoids in plasma and serum by gas chromatography-mass spectrometry

Abstract

The aim of this work was to develop and validate a solid-phase extraction (SPE) method for the analysis of cannabinoids with emphasis on a very extensive and effective matrix reduction in order to ensure constant good results in selectivity and sensitivity regardless of the applied measuring technology. This was obtained by the use of an anion exchange sorbent (AXS) and the purposive ionic interaction between matrix components and this sorbent material. In a first step, the neutral cannabinoids ∆9-tetrahydrocannabinol (THC) and 11-hydroxy-∆9-tetrahydrocannabinol (11-OH-THC) were eluted, leaving 11-nor-9-carboxy-∆9-tetrahydrocannabinol (THC-COOH) and the main interfering matrix components bound to the AXS. In a second step, exploiting differences in pH and polarity, it was possible to separate matrix components and THC-COOH, thereby yielding a clean elution of THC-COOH into the same collecting tube as THC and 11-OH-THC. Even when using a simple measuring technology like gas chromatography with single quadrupole mass spectrometry, this two-step elution allows for an obvious decrease in number and intensity of matrix interference in the chromatogram. Hence, in both plasma and serum, the AXS extracts resulted in very good selectivity. Limits of detection and limits of quantification were below 0.25 and 0.35 ng/mL for the neutral cannabinoids in both matrices, 2.0 and 3.0 ng/mL in plasma and 1.6 and 3.3 ng/mL in serum for THC-COOH. The recoveries were ≥79.8 % for all analytes. Interday and intraday imprecisions ranged from 0.8 to 6.1 % relative standard deviation, and accuracy bias ranged from -12.6 to 3.6 %.

Investigation of phase II metabolism of 11-hydroxy-Δ-9-tetrahydrocannabinol and metabolite verification by chemical synthesis of 11-hydroxy-Δ-9-tetrahydrocannabinol-glucuronide

“…The metabolites O1-O3 are assumed to be OH-THC derivates, as the exact mass fits the OH-THC derivates and the HESI(+)-MS-2 spectra showed similar neutral losses as the known metabolites 11-OH-Δ-9-THC and 8-OH-Δ-9-THC. The biotransformation of different hydroxy-metabolites is in line with several studies of in vivo and/or in vitro hydroxylation of (−)-Δ-9-THC [4][5][6][23][24][25][26]. In the range of 2 to 4 min, the signals can be assigned to in source fragments of OH-THC-glucuronides because they have the same retention time as the m/z 507.2589 of the glucuronides.…”

Developing a novel packed in‐tube solid‐phase extraction method for determination ∆9‐tetrahydrocannabinol in biological samples and cannabis leaves

“…The analytical performance of the packed CuCoCr (NO 3 )‐LDH IT‐SPE method for the extraction and determination of THC was compared with other similar methods in the literature and the results are summarized in Table . As Table shows, the CuCoCr (NO 3 )‐LDH sorbent exhibited a greater extraction ability compared to other sorbents such as polydimethylsiloxane, p(MAA‐co‐EGDMA) monolithic capillary, and C‐8/quaternary amine/silica material for THC.…”

Extraction of naturally occurring cannabinoids: an update

“…Unlike traditional SPE devices, in DPX, solutions are mixed with the sorbent in a dispersive manner to provide rapid equilibration 52 . A simple SPE method using anion exchange sorbent was employed for the extraction of cannabinoids from plasma and serum, prior to GC–MS analysis 53 . Earlier, Pelicao et al 54 reported a SPE‐based extraction method for GC–MS analysis of several illicit drugs including cannabinoids from postmortem blood samples.…”