Pesticide analysis in cannabis products

Evaluation of Iron Chlorin e6 disappearance and hydrolysis in soil and garlic using salting-out assisted liquid-liquid extraction coupled with high-performance liquid chromatography and ultraviolet-visible detection

Iron Chlorin e6 (ICE6), a star plant growth regulator (PGR) with independent intellectual property rights in China, has demonstrated its efficacy through numerous field experiments. We innovatively employed salting-out assisted liquid-liquid extraction (SALLE) with HPLC-UV/Vis to detect ICE6 residues in water, soil, garlic seeds, and sprouts. Using methanol and a C18 column with acetonitrile: 0.1% phosphoric acid mobile phase (55:45, v:v), we achieved a low LOQ of 0.43 to 0.77 μg kg-1. Calibration curves showed strong linearity (R2 > 0.992) within 0.01 to 5.00 mg kg-1. Inter-day and intra-day recoveries (0.05 to 0.50 mg kg-1) demonstrated high sensitivity and accuracy (recoveries: 75.36% to 107.86%; RSD: 1.03% to 8.78%). Additionally, density functional theory (DFT) analysis aligned UV/Vis spectra and indicated ICE6's first-order degradation (2.03 to 4.94 days) under various environmental conditions, mainly driven by abiotic degradation. This study enhances understanding of ICE6's environmental behavior, aids in risk assessment, and guides responsible use in agroecosystems.

Analysis of 207 residual pesticides in hot pepper powder using LC-MS/MS

This study investigated the determination of 207 pesticides in hot pepper powder and found patterns of pesticide use by production from five regions, detecting a total of 50 pesticides. The LOD, LOQ and recoveries of pesticides were 0.08-2.53, 0.25-7.60 μg kg-1, and 81.0-132.1%, respectively. The Horrat values ranged from 0.07 to 1.97. A total of 50 residual pesticides were detected in 963 hot pepper powder samples. All residual pesticide levels were below the Korean maximum residue level (MRL) and the %ADI was ≤ 0.001-0.076%. Seven pesticides had a detection rate above 50% (tebuconazole, pyraclostrobin, etofenprox, flonicamid, imidacloprid, carbendazim, and flubendiamide). The region where the most pesticide types were detected was Ham-pyeong with 38 types. Tebuconazole had detection rates of > 90% in all regions. In the PCA results with factor analysis, each region shows patterns of pesticide use. Four regions focus on Aphidoidea control and one region on Colletotrichum acutatum control.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01443-6.

Modeling a pesticide remediation strategy for preparative liquid chromatography using high-performance liquid chromatography

BACKGROUND

Cannabis sativa L. also known as industrial hemp, is primarily cultivated as source material for cannabinoids cannabidiol (CBD) and ∆9-tetrahydrocannabinol (∆9-THC). Pesticide contamination during plant growth is a common issue in the cannabis industry which can render plant biomass and products made from contaminated material unusable. Remediation strategies to ensure safety compliance are vital to the industry, and special consideration should be given to methods that are non-destructive to concomitant cannabinoids. Preparative liquid chromatography (PLC) is an attractive strategy for remediating pesticide contaminants while also facilitating targeted isolation cannabinoids in cannabis biomass.

METHODS

The present study evaluated the benchtop-scale suitability of pesticide remediation by liquid chromatographic eluent fractionation, by comparing retention times of 11 pesticides relative to 26 cannabinoids. The ten pesticides evaluated for retention times are clothianidin, imidacloprid, piperonyl butoxide, pyrethrins (I/II mixture), diuron, permethrin, boscalid, carbaryl, spinosyn A, and myclobutanil. Analytes were separated prior to quantification on an Agilent Infinity II 1260 high performance liquid chromatography with diode array detection (HPLC-DAD). The detection wavelengths used were 208, 220, 230, and 240 nm. Primary studies were performed using an Agilent InfinityLab Poroshell 120 EC-C18 3.0 × 50 mm column with 2.7 μm particle diameter, using a binary gradient. Preliminary studies on Phenomenex Luna 10 μm C18 PREP stationary phase were performed using a 150 × 4.6 mm column.

RESULTS

The retention times of standards and cannabis matrices were evaluated. The matrices used were raw cannabis flower, ethanol crude extract, CO₂ crude extract, distillate, distillation mother liquors, and distillation bottoms. The pesticides clothianidin, imidacloprid, carbaryl, diuron, spinosyn A, and myclobutanil eluted in the first 3.6 min, and all cannabinoids (except for 7-OH-CBD) eluted in the final 12.6 min of the 19-minute gradient for all matrices evaluated. The elution times of 7-OH-CBD and boscalid were 3.44 and 3.55 min, respectively.

DISCUSSION

7-OH-CBD is a metabolite of CBD and was not observed in the cannabis matrices evaluated. Thus, the present method is suitable for separating 7/11 pesticides and 25/26 cannabinoids tested in the six cannabis matrices tested. 7-OH-CBD, pyrethrins I and II (RT_A: 6.8 min, RT_B: 10.5 min), permethrin (RT_A: 11.9 min, RT_B: 12.2 min), and piperonyl butoxide (RT_A: 8.3 min, RT_B: 11.7 min), will require additional fractionation or purification steps.

CONCLUSIONS

The benchtop method was demonstrated have congruent elution profiles using preparative-scale stationary phase. The resolution of pesticides from cannabinoids in this method indicates that eluent fractionation is a highly attractive industrial solution for pesticide remediation of contaminated cannabis materials and targeted isolation of cannabinoids.

Heavy metal and phthalate contamination and labeling integrity in a large sample of US commercially available cannabidiol (CBD) products

BACKGROUND

The demand and availability of commercially available cannabidiol (CBD) products has grown substantially, which is of particular interest among medically vulnerable people. Because the cannabis plant is recognized as a bioaccumulator, which is highly effective at absorbing and retaining contaminants (e.g., heavy metals) in soil, it is important to characterize the degree of contamination in CBD products and their label accuracy to better estimate potential health benefits and risks associated with consumption.

METHODS

Levels of lead, cadmium, arsenic, mercury, four phthalates, and CBD labeling accuracy were quantified in a selection of commercially available CBD products in the US. Heavy metal concentrations were quantified by inductively coupled plasma-mass spectrometry. Phthalates were quantified by liquid chromatography-tandem mass spectrometry. CBD labeling accuracy was determined by extracting samples into a suitable organic solvent and analyzing using liquid chromatography with diode array detection.

RESULTS

Lead was detected in 42 %, cadmium in 8 %, arsenic in 28 %, and mercury in 37 % of 121 edible CBD products. Four edible CBD products exceeded the California Proposition 65 threshold for daily lead consumption of 0.5μg in two servings. The percentage of edible products with detectable phthalate concentrations varied between 13 % and 80 % across the four phthalates, with DEHP being most prevalent. Among all products tested for CBD labeling accuracy (topicals, edibles, N = 516), 40 % contained <90 % of the CBD indicated on the product label, 18 % contained >110 %, and only 42 % of products fell within ±10 % of the CBD claimed on the manufacturer label. Concentrations of heavy metals and phthalates were not associated with CBD potency.

CONCLUSIONS

Low-level contamination of edible CBD products with heavy metals and phthalates is pervasive. There is substantial discrepancy between the product label claims for CBD potency and the amount measured in both edible and topical products, underscoring the need for tight regulations for CBD product label integrity to protect consumers.

Selective isolation of pesticides and cannabinoids using polymeric ionic liquid-based sorbent coatings in solid-phase microextraction coupled to high-performance liquid chromatography

The high abundance of cannabinoids within cannabis samples presents an issue for pesticide testing as cannabinoids are often co-extracted with pesticides using various sample preparation techniques. Cannabinoids may also chromatographically co-elute with moderate polarity pesticides and inhibit the ionization of pesticides when using mass spectrometry. To circumvent these issues, we have developed a new approach to isolate commonly regulated pesticides and cannabinoids from aqueous samples using tunable, crosslinked imidazolium polymeric ionic liquid (PIL)-based sorbent coatings for direct immersion solid-phase microextraction (DI-SPME). The selectivity of four PIL sorbent coatings towards 20 pesticides and six cannabinoids, including cannabidiol and Δ⁹-THC, was investigated and compared against a commercial PDMS/DVB fiber. Extraction and desorption conditions, including salt content, extraction temperature, pH, extraction time, desorption solvent, and desorption time, were optimized using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Under optimized conditions, the PIL fiber consisting of 1-vinylbenzyl-3-octylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([VBIMC₈⁺][NTf₂^-]) and 1,12-di(3-vinylbenzylimidazolium)dodecane dibis[(trifluoromethyl)sulfonyl]imide ([(VBIM)₂C₁₂²⁺]2[NTf₂^-]) sorbent coating provided the best selectivity towards pesticides compared to other PILs and the PDMS/DVB fibers and was able to reach limits of detection (LODs) as low as 1 µg/L. When compared to a previously reported PIL-based SPME HPLC-UV method for pesticide analysis, the amount of cannabinoids extracted from the sample was decreased 9-fold while a 4-fold enhancement in the extraction of pesticides was achieved. Additionally, the PIL-based SPME method was applied to samples containing environmentally-relevant concentrations of pesticides and cannabinoids to assess its feasibility for Cannabis quality control testing. Relative recoveries between 95% and 141% were obtained using the PIL sorbent coating while recoveries ranging from 50% to 114% were obtained using the PDMS/DVB fiber.

Bioactive nutraceutical ligands and their efficiency to chelate elemental iron of varying dynamic oxidation states to mitigate associated clinical conditions

The natural bioactive or nutraceuticals exhibit several health benefits, including anti-inflammatory, anti-cancer, metal chelation, antiviral, and antimicrobial activity. The inherent limitation of nutraceuticals or bioactive ligand(s) in terms of poor pharmacokinetic and other physicochemical properties affects their overall therapeutic efficiency. The excess of iron in the physiological compartments and its varying dynamic oxidation state [Fe(II) and Fe(III)] precipitates various clinical conditions such as non-transferrin bound iron (NTBI), labile iron pool (LIP), ferroptosis, cancer, etc. Though several natural bioactive ligands are proposed to chelate iron, the efficiency of bioactive ligands is limited due to poor bioavailability, denticity, and other related physicochemical properties. The present review provides insight into the relevance of studying the dynamic oxidation state of iron(II) and iron(III) in the physiological compartments and its clinical significance for selecting diagnostics and therapeutic regimes. We suggested a three-pronged approach, i.e., diagnosis, selection of therapeutic regime (natural bioactive), and integration of novel drug delivery systems (NDDS) or nanotechnology-based principles. This systematic approach improves the overall therapeutic efficiency of natural iron chelators to manage iron overload-related clinical conditions.

Analytical derivatizations in environmental analysis

Analytical derivatization is a technique that alters the structure of an analyte and produces a product more suitable for analysis. While this process can be time-consuming and add reagents to the procedure, it can also facilitate the isolation of the analyte(s), enhance analytes' stability, improve separation and sensitivity, and reduce matrix interferences. Since derivatization is a functional group analysis, it improves selectivity by separating reactive from neutral compounds during sample preparation. This technique introduces detector-orientated tags into analytes that lack suitable physicochemical properties for detection at low concentrations. Notably, many regulatory bodies, especially those in the environmental field, require these characteristics in analytical methods. This review focuses on note-worthy analytical derivatization methods employed in environmental analyses with functional groups, phenol, carboxylic acid, aldehyde, ketone, and thiol in aqueous, soil, and atmospheric sample matrices. Both advantages and disadvantages of analytical derivatization techniques are discussed. In addition, we discuss the future directions of analytical derivatization methods in environmental analysis and the potential challenges.

Recent applications of chromatography for analysis of contaminants in cannabis products: a review

In the last few years, the cultivation of cannabis has been increasing due to greater use in foods, recreational use, creams, oils, and other applications. Thus, analysis of contaminants (e.g. pesticides and mycotoxins) in cannabis products is necessary to ensure consumer safety. This review is focused on the analytical procedures, based on chromatographic techniques, used for the determination of contaminants in cannabis and related products, developed from 2015 to 2020. QuEChERS (acronym of quick, easy, cheap, effective, rugged and safe) was mainly used for the extraction of pesticides and other contaminants from cannabis because its versatility and capacity to extract a wide range of substances, and therefore, increasing the scope of the analysis. The most employed technique to determine pesticides and mycotoxins in cannabis products was liquid chromatography (LC) coupled to mass spectrometry (MS), although gas chromatography (GC) coupled to MS was also employed for the analysis of non-polar compounds, using triple quadrupole (QqQ) as mass analyzer. Nevertheless, new advances in cannabis analysis are also discussed, introducing techniques such as high-resolution mass spectrometry (HRMS), which allows for performing both targeted and untargeted (unknown and suspect) analyses. © 2021 Society of Chemical Industry.

In vitro metabolism of tebuconazole, flurtamone, fenhexamid, metalaxyl-M and spirodiclofen in Cannabis sativa L. (hemp) callus cultures

BACKGROUND

Cannabis sativa L. (hemp) is a medicinal plant producing various cannabinoids. Its consumption is legalized for medical use due to the alleged positive health effects of these cannabinoids. To satisfy the demand, C. sativa plants are propagated in contained growth chambers. During indoor propagation, pesticides usually are used to ensure efficient production. However, pesticide registration and safe application in C. sativa has not been investigated in detail.

RESULTS

With this study the metabolic degradation of pesticides in recently established C. sativa callus cultures was examined. Tebuconazole, metalaxyl-M fenhexamid, flurtamone and spirodiclofen were applied at 10 μm for 21 days. Results were compared with metabolism data obtained from Brassica napus L., Glycine max (L.) Merr., Zea mays L. and Tritium aestivum L. callus cultures as well as in metabolism guideline studies. The successfully established C. sativa callus cultures were able to degrade pesticides by oxidation, demethylation, and cleavage of ester bonds in phase I, as well as glycosylation and conjugation with malonic acid in phase II and III. Initial metabolites were detected after Day (D)7 and were traced at D21.

CONCLUSION

The resulting pathways demonstrate the same main degradation strategies as crop plants. Because metabolites could be the main residue, the exposure of consumers to these residues will be of high importance. We present here an in vitro assay for a first estimation of pesticide metabolism in C. sativa. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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

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 solid-phase 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.

Macro and Trace Elements in Hemp (Cannabis sativa L.) Cultivated in Greece: Risk Assessment of Toxic Elements

The accumulation of hazardous contaminants in Cannabis sativa L. raises warning signs regarding possible adverse effects on human health due to the consumption of herbal medicines and/or other herbal edible products made from cannabis. Thus, there is an urge to investigate the levels of hazardous contaminants, such as heavy metals, in cannabis plant. In the present study, 29 macro and trace elements, including both beneficial and toxic elements (heavy metals and metalloids), were investigated in 90 samples of Cannabis sativa L. collected from Greece. According to the results, the detected concentrations of macro elements in the leaves/flowers of cannabis ranged between 28 and 138,378 ppm, and of trace elements between 0.002 and 1352.904 ppm. Although the concentrations of elements varied among the samples, their accumulation pattern was found to be similar, with the contribution of toxic elements to the total concentration of trace elements being below 1%. The detected levels of the most toxic elements were below the prescribed limits established by the WHO, while the calculated THQ and CR values showed no risk (non-carcinogenic and carcinogenic) for the population exposed to the current cannabis samples. Positive correlation between the concentration of elements and cannabis geographical origin and variety was observed. Cannabis leaves/flowers were more contaminated with trace and macro elements than seeds.

Validation of a high-throughput method for analysis of pesticide residues in hemp and hemp products

Hemp has been an agricultural commodity for millennia, and it has been undergoing a resurgence in interest and production due to its high content of cannabinoids, protein, fiber and other ingredients. For legal possession and use throughout the USA, hemp and hemp products must have delta-9-tetrahydrocannabinol (THC) concentration < 0.3%. As with most crops, pesticides may be applied when farming hemp, which need to be monitored in food, feed, and medicinal products. The aim of this work was to evaluate and validate the recently developed "quick, easy, cheap, effective, rugged, safe, efficient, and robust" (QuEChERSER) sample preparation mega-method to determine pesticide residues in hemp plants, flowers, powders, oils, and pellets. High-throughput analysis of final extracts for 106 targeted pesticides and metabolites from North American monitoring lists entailed: 1) ultrahigh-performance liquid chromatography - tandem mass spectrometry (UHPLC-MS/MS) with column back-flushing, and 2) instrument-top sample preparation + low-pressure gas chromatography (ITSP+LPGC-MS/MS). In QuEChERSER, 2 g sample is extracted with 10 mL 4/1 (v/v) acetonitrile/water by mechanical shaking for 10 min, followed by 3 min centrifugation. For LC, 0.2 mL of extract is taken and solvent exchanged into initial mobile phase followed by 5 min ultra-centrifugation prior to the 10 min analysis. For GC-amenable pesticides, the remaining initial extract is partitioned with 4/1 (w/w) anh. MgSO₄/NaCl, and 1 mL is taken for automated ITSP cleanup in parallel with 10 min LPGC analysis. In the former case, the UHPLC column is back-flushed with 1/1 (v/v) methanol/acetonitrile for 3 min between each injection to keep the system clean and avoid ghost peaks. Multi-level, multi-day validation results achieved 70-120% recoveries with RSDs < 20% for more than 80% of the analytes in hemp protein powder, oil, pellets, and fresh plant (dried hemp plant and flower were too complex). Limits of quantification (LOQs) were < 10 ng/g were achieved for nearly all pesticides, yielding 2.8% false negatives among >13,000 analyte results in the spiked samples. The QuEChERSER method was demonstrated to meet the challenge for several complex hemp matrices.

Recent advances in analytical methods for the determination of citrinin in food matrices

Citrinin is a toxic small organic molecule produced as a secondary metabolite by fungi types Penicillium, Monascus and Aspergillus and is known to contaminate various food commodities during postharvest stages of food production. During the last 10 years, most reported methods for citrinin analysis employed enzyme-linked immunosorbent assays or high-performance liquid chromatography. Over this same time period, liquid extraction, solid-phase extraction, dispersive liquid-liquid microextraction and QuEChERS were the most cited sample preparation and clean-up methods. In this review the advantages and disadvantages of the various sample preparation, separation and detection methods for citrinin analysis over the last decade are evaluated. Furthermore, current trends, emerging technologies and the future prospects of these methods are discussed.

Cannabinomics: Application of Metabolomics in Cannabis (Cannabis sativa L.) Research and Development

Cannabis (Cannabis sativa L.) is a complex, polymorphic plant species, which produces a vast array of bioactive metabolites, the two major chemical groups being cannabinoids and terpenoids. Nonetheless, the psychoactive cannabinoid tetrahydrocannabinol (Δ 9 -THC) and the non-psychoactive cannabidiol (CBD), are the two major cannabinoids that have monopolized the research interest. Currently, more than 600 Cannabis varieties are commercially available, providing access to a multitude of potent extracts with complex compositions, whose genetics are largely inconclusive. Recently introduced legislation on Cannabis cultivation in many countries represents a great opportunity, but at the same time, a great challenge for Cannabis research and development (R&D) toward applications in the pharmaceutical, food, cosmetics, and agrochemical industries. Based on its versatility and unique capabilities in the deconvolution of the metabolite composition of complex matrices, metabolomics represents an ideal bioanalytical tool that could greatly assist and accelerate Cannabis R&D. Among others, Cannabis metabolomics or cannabinomics can be applied in the taxonomy of Cannabis varieties in chemovars, the research on the discovery and assessment of new Cannabis-based sources of bioactivity in medicine, the development of new food products, and the optimization of its cultivation, aiming for improvements in yield and potency. Although Cannabis research is still in its infancy, it is highly foreseen that the employment of advanced metabolomics will provide insights that could assist the sector to face the aforementioned challenges. Within this context, here, the current state-of-the-art and conceptual aspects of cannabinomics are presented.

Ultra-High-Performance Liquid Chromatography Coupled with Quadrupole Orbitrap High-Resolution Mass Spectrometry for Multi-Residue Analysis of Mycotoxins and Pesticides in Botanical Nutraceuticals

Cannabidiol (CBD) food supplements made of Cannabis sativa L. extracts have quickly become popular products due to their health-promoting effects. However, potential contaminants, such as mycotoxins and pesticides, can be coextracted during the manufacturing process and placed into the final product. Accordingly, a novel methodology using ultra-high-performance liquid chromatography coupled with quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was developed to quantify 16 mycotoxins produced by major C. sativa fungi, followed by a post-target screening of 283 pesticides based on a comprehensive spectral library. The validated procedure was applied to ten CBD-based products. Up to six different Fusarium mycotoxins were found in seven samples, the most prevalent being zearalenone (60%) and enniatin B1 (30%), both found at a maximum level of 11.6 ng/g. Co-occurrence was observed in four samples, including one with enniatin B1, enniatin A and enniatin A1. On the other hand, 46 different pesticides were detected after retrospective analysis. Ethoxyquin (50%), piperonyl butoxide (40%), simazine (30%) and cyanazine (30%) were the major residues found. These results highlight the necessity of monitoring contaminants in food supplements in order to ensure a safe consumption, even more considering the increase trend in their use. Furthermore, the developed procedure is proposed as a powerful analytical tool to evaluate the potential mycotoxin profile of these particular products.