Single-Run Separation and Quantification of 14 Cannabinoids Using Capillary Electrophoresis

Abstract

Quantification of major cannabinoids in cannabis products is normally performed using high-pressure liquid chromatography (HPLC)-based methods. We propose a cost-effective alternative method that successfully separates and quantifies 14 cannabinoids in a single run using capillary electrophoresis (CE) coupled with a UV detector in 18 min. The separation is carried out in 60% acetonitrile in the presence of 6.5 mM sodium hydroxide and 25 µM β-cyclodextrin, resulting in good separation of cannabinoids. Our CE method demonstrated the limit of detection between 1.2–1.8 µg/mL, with the linear range reaching up to 50 µg/mL. We validated the method performance by testing a plant extract and quantifying cannabinoid content. This method is the first to separate 14 cannabinoids in one run using a CE system with UV detection.

Analytical Techniques for Phytocannabinoid Profiling of Cannabis and Cannabis-Based Products—A Comprehensive Review

“…Mechanical grinding-activation in an intensity planetary vibrational mill [ 62 , 63 ], ball mill [ 55 ], knife mill [ 64 ] or freeze mill [ 65 ] are also applied. Instead of drying, fresh cannabis plant material can be frozen with liquid nitrogen and crushed [ 66 , 67 ] or frozen, lyophilised at −50 °C and grounded by hand [ 68 ] or in a mill [ 69 ]. Comparison of coarse homogenization by sieving through a 1-mm mesh and fine homogenization with a ball mill revealed better extraction efficiency for CBDA and THCA for the finely powdered plant material, and no difference for the neutral phytocannabinoids (CBD, Δ 9 -THC) [ 55 ].…”

“…After extraction of cannabis plant material, additional filtrationis performed, using sintered glass disc [ 44 ], sterile cotton plugs [ 9 , 75 , 143 , 144 ], PFTE syringe filters, with 0.22 µm [ 68 , 111 ] or 0.45 µm pore size [ 56 , 94 , 95 , 108 ], millipore filter (0.45 µm) [ 50 , 84 ], nylon filters (0.45 µm) [ 133 ], membrane filter [ 49 ], PVD filter (0.22 µm) [ 113 ] or, alternatively, drying on MgSO 4 and filtration [ 67 , 138 ]. The insoluble plant material can also be removed by vacuum filtration.…”

“…Binary mobile phase system consisted of H 2 O/MeOH (10:90, v/v ) [ 186 ], H 2 O/MeOH (17/83, v/v ) [ 187 ] and H 2 O + 0.1% formic acid/MeOH + 0.1%; formic acid is most commonly used for phytocannabinoid profiling [ 11 , 63 , 65 , 147 , 185 , 188 ]. Other binary systems that provide good peak shape and improved resolution are also used, such as H 2 O + 0.1% formic acid/MeCN + 0.1% formic acid [ 40 , 55 , 64 , 80 , 109 , 134 , 144 , 182 , 183 , 185 , 188 , 189 ], H 2 O + 0.1% TFA/MeOH + 0.1% TFA [ 68 ], MeCN/H 2 O (75:25, + 0.05% formic acid, v/v )/isopropanol:MeCN (80:20 + 0.05% formic acid, v/v ) [ 183 , 184 ], 5% MeCN + 0.1% formic acid/MeCN + 5% H 2 O + 0.1% formic acid [ 78 ], H 2 O + 0.1% formic acid/MeCN [ 27 , 63 , 185 ], 5% MeCN + 0.1% formic acid/80% MeCN + 0.1% formic acid [ 69 ] and MeCN/H 2 O + 0.85% phosphoric acid [ 42 ].…”

“…For DAD, a narrower range is selected (i.e., 200–400 nm [ 83 ], 190–500 nm [ 182 ]). Single wavelength can be selected for evaluation of multiple phytocannabinoids in hemp seed oils [ 179 ], in plant material (230 nm) [ 68 ], 214 nm [ 188 , 189 ] or 220 nm in plant material and resins [ 69 , 165 ] or cannabis extracts [ 27 ], in commercial veterinary supplements (225 nm) [ 192 ] or for quantification of Δ 9 -THC, Δ 9 -THCA, CBN and CBD (210 nm) [ 191 ] or Δ 9 -THC and Δ 9 -THCA in plant material (211 nm and 220 nm) [ 185 ]. For wide range methods, such as cannabis-based medical extracts [ 182 ], cannabis-infused cholcolate [ 65 ] and 17 phytocannabinoids in cannabis inflorescences and oils [ 100 ], 228 nm has been shown to be the most suitable.…”

“…Most commonly used MS analyzers include simple Q spectrometers [ 181 ], QQQ analyzers [ 11 , 58 , 68 , 97 , 114 , 147 , 193 , 194 ], IT analyzers [ 28 , 43 , 72 , 185 ], QTRAP [ 67 , 159 , 191 , 195 ] or high resolution-accurate mass MS (HRAM-MS) analysers, such as Q-TOF [ 83 , 88 , 139 , 189 ] and Q-Exactive TM Orbitrap [ 19 , 63 , 65 , 66 ].…”