Analysis of the California list of pesticides, mycotoxins, and cannabinoids in chocolate using liquid chromatography and low‐pressure gas chromatography‐based platforms

Abstract

Cannabis legalization has led to the development of a variety of cannabis-infused products with edibles being one of the most popular. The state of California has implemented comprehensive cannabis testing regulations requiring the analysis of cannabinoids (potency) and contaminants, such as pesticides and mycotoxins, in any type of cannabis good. In this work, we propose an analytical workflow for the quantification of the California list of pesticides and mycotoxins, as well as six cannabinoids, in chocolate, using 3 mL of solvent for the extraction. For the analysis of pesticides and mycotoxins, clean-up steps employing a C18 solidphase extraction cartridge and dispersive solid-phase extraction sorbents were implemented. Gas chromatography amenable pesticides were analyzed using low-pressure gas chromatography coupled to tandem mass spectrometry which allowed for a total method run of 12 min. Both liquid chromatography and gas chromatography instrumental methods had the same analysis time, ensuring satisfactory sample throughput. For the determination of cannabinoids, a dilution of the original organic extract collected for pesticides and mycotoxins analysis (and prior to any clean-up step) was used. Excellent results in terms of analytical figures of merit were obtained for all target analytes.

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

“…The minimization of analyte loss using manual grinder is attributed to the adhesion of cannabis resin to the blades and plastic housing surface of a plastic blender during the high-speed pulverization [ 50 ]. 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 ].…”

“…Solvent exchange may also be included as final step, by diluting extracts with solvents and solvent mixtures more similar to the mobile phases employed, in case of (HP)LC analysis. For example, cannabis-infused chocolate is first soaked in IS solutions and isopropyl alcohol, extracted with MeCN + 1% acetic acid and finally diluted with MeCN prior to LC-MS/MS or MeCN/H 2 O (75:25, v/v ) prior to HPLC-UV analysis [ 65 ].…”

“…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 ].…”

“…Other buffering solutions are less frequently used, such as 0.1% acetic acid in a tertiary system, e.g., H 2 O + 0.1% acetic acid/MeCN + 0.1% acetic acid/MeOH [ 19 ], MeCN/0.5% acetic acid (66:34, v/v ) [ 190 ], ammonium formate in a binary system MeOH/H 2 O + 50 mM ammonium formate (pH 5.19) [ 83 ], 5 mM ammonium formate + 0.1% HCOOH/MeCN + 0.1% HCOOH [ 65 , 100 ] or 5 mM ammonium formate/MeCN + 0.1% HCOOH [ 92 ].…”

“…Raptor ARC-18 is the C 18 column with the widest applicability in phytocannabinoid profiling, offering the most appropriate separation of 17 phytocannabinoids (CBG, CBD, CBN, Δ 9 -THC, Δ 8 -THC, THCA, THCV, THCVA, CBC, CBCA, CBGA, CBDA, CBL, CBLA, CBDV, CBDVA, CBLA) at a runtime suitable for commercial environment. It improves peak resolution issue of some of the aforementioned columns, such as Kinetex C 18 , Luna C 18 , Luna Polar C 18 and Raptor C 18 [ 100 ] and has been shown to, together with Raptor ARC-18 EXP guard column, be suitable for analysis of pesticides, mycotoxins and cannabinoids [ 65 ].…”