Determination of pesticide residues in soybeans using QuEChERS followed by deep eutectic solvent-based DLLME preconcentration prior to gas chromatography-mass spectrometry analysis

A reliable and greener alternative to the usual extraction methods is reported for the determination of pesticide residues in soybeans. This novel approach combines the classical QuEChERS extraction method with a DLLME (dispersive liquid-liquid microextraction) step, utilizing a deep eutectic solvent (DES) - camphor: hexanoic acid (1:1 molar ratio) - as the microextraction solvent. This DES has never been employed in pesticide analysis by gas chromatography-mass spectrometry of complex matrices like soybeans. A Plackett-Burman screening design was employed to optimize sample preparation variables of QuEChERS (amount of sodium chloride and magnesium sulfate, and amount of PSA and C18 sorbents) and DLLME (pH of medium, amount of sodium chloride, and volume of microextraction solvent). This design allowed for a systematic evaluation of the impact of each parameter on the method's performance. The optimized method was evaluated using a certified reference material and commercial samples of soybeans. The method exhibited high accuracy and precision for most of the analytes under study, demonstrating its applicability for pesticide residue analysis in soybeans. To assess the greenness and practicality of the developed method, the Analytical Greenness (AGREE) and Blue Applicability Grade Index (BAGI) metric systems were employed, respectively. Overall, the proposed QuEChERS-DLLME method using a DES solvent is a reliable and greener alternative to conventional extraction methods for the determination of pesticide residues in soybeans. Its high performance, coupled with its environmental friendliness, makes it a promising tool for food safety analysis.