Cannabinoids assessment in plasma and urine by high performance liquid chromatography-tandem mass spectrometry after molecularly imprinted polymer microsolid-phase extraction

Abstract

A molecularly imprinted polymer (MIP) selective for cannabinoids [Δ⁹-tetrahydrocannabinol (Δ9-THC), 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (Δ9-THC-COOH), and 11-hydroxy-Δ⁹-tetrahydrocannabinol (Δ9-THC-OH)] has been synthesized, fully characterized, and applied to the assessment of plasma and urine analysis of marijuana abuse by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Δ9-THC-COOH was used as a template molecule, whereas ethylene glycol dimethacrylate (EGDMA) was used as a functional monomer, divinylbenzene (DVB) as a cross-linker, and 2,2'-azobisisobutyronitrile (AIBN) as an initiator. The prepared MIP was found to be highly selective for cannabinoids typically found in blood and urine, and also for cannabinol (CBN) and cannabidiol (CBD). MIP beads (50 mg) were loaded inside a cone-shaped device made of a polypropylene (PP) membrane for microsolid-phase extraction (μ-SPE) in batch mode. Optimum retention of analytes (0.1 to 1.0 mL of plasma/urine) was achieved by fixing plasma/urine pH at 6.5 and assisting the procedure by mechanical shaking (150 rpm, 40 °C, 12 min). Optimum elution conditions implied 2 mL of a 90:10 methanol/acetic acid and ultrasound extraction (35 kHz, 325 W) for 6 min. Good precision was assessed by intra-day and inter-day assays. In addition, the method was found to be accurate after intra-day and inter-day analytical recovery assays and after analyzing control serum and urine control samples. The limits of quantification were in the range of 0.36-0.49 ng L^-1 (plasma analysis) and 0.47-0.57 ng L^-1 (urine analysis). These values are low enough for confirmative conclusions regarding marijuana abuse through blood and urine analysis. Graphical Abstract ᅟ.

Keywords: Cannabinoids; High performance liquid chromatography–tandem mass spectrometry; Microsolid-phase extraction; Molecularly imprinted polymer; Plasma; Urine.