Combination of switchable hydrophilic solvent liquid–liquid microextraction with QuEChERS for trace determination of triazole fungicide pesticides by GC–MS

This work first proposed a novel green and efficient method based on Quick, Easy, Cheap, Efficient, Rugged, and Safe pretreatment (QuEChERS) combined with switchable hydrophilic solvent homogeneous liquid–liquid microextraction (SHS-HLLME) for trace determination of triazole fungicides (TFs) in agricultural products such as vegetables and fruits by gas chromatography–mass spectrometry (GC–MS). N , N -Dimethyl benzylamine was used for the synthesis of SHS. Box–Behnken design was applied for the optimization of extraction conditions and a mathematical model was obtained. Ultimately, 0.50 mL SHS, 1.0 mL 10 mol L −1 sodium hydroxide, and 45 s ultrasonic time were determined as optimal conditions for the SHS-HLLME method. The limit of detection and limit of quantification determined using the optimal method (SHS-HLLME/GC–MS) were 0.13–0.27 ng mL −1 and 0.43–0.90 ng mL −1 , respectively. In addition, the SHS-HLLME method under optimal conditions was combined with the traditional QuEChERS method to realize the advancement of the SHS-HLLME method from simple to complex matrix analysis, and the QuEChERS–SHS-HLLME method was successfully applied to the analysis of TFs in cucumbers, tomatoes, watermelon and grapes in agricultural products. Matrix-matched calibration standards were used to improve the accuracy of TFs in spiked cucumber samples to obtain recovery results close to 100%. It was shown that the new method is green and rapid, enabling fast and inexpensive sample pretreatment with up to 100-fold enrichment factor and low detection limit compared with the original QuEChERS method. Graphical abstract