Development of a green analytical methodology based on a deep eutectic solvent for the determination of pesticide residues in industrial hemp

Abstract

In this study, in accordance with the green analytical chemistry principles, the use of eco-friendly solvents has been proposed for the first time for the analysis of pesticide residues in industrial hemp (Cannabis sativa L.). With this aim, betaine-based natural deep eutectic solvents with lactic acid and propylene glycol were explored as extraction solvents in the solid–liquid extraction of fifteen pesticides from hemp samples. The mixture composed of betaine:propylene glycol at molar ratio 1:4 (n/n) was selected due to its better analytical performance. The separation, identification and quantification of pesticides were carried out by gas chromatography coupled to tandem mass spectrometry. The extraction protocol was optimised through the step-by-step strategy, evaluating NADES composition, water addition to the solvent, solid–liquid ratio, and re-extraction solvent. The analytical methodology was validated in terms of calibration (linear regression with R2 ≥0.9966), trueness and precision (average relative recovery of 63–77% with relative standard deviation ≤20%) and sensitivity (limits of quantification of 0.663–3.625 µg/kg). These results successfully demonstrated the convenience of the developed approach for the determination of pesticides in industrial hemp, which has industrial applications such as the production of food and supplements, cosmetics, and textiles, which should not compromise the health of consumers. In addition, the comparison with previously reported research in this field showed that not only the present method is more sensitive, but also more sustainable and economical.