Experimental-design-based optimization of dispersive liquid-liquid microextraction coupled with gas chromatography–negative-ion chemical ionization–mass spectrometry for the determination of pyrethroids in agricultural products and drinks

Pyrethroids are synthetic chemicals that account for 16% of the international insecticide market and have been shown to be of varying toxicity to different species. There are various methods available for detecting pyrethroids in agricultural products, but these products must be pre-treated to remove interference from the food matrix, such as through dispersion liquid-liquid microextraction (DLLME). This study employed two experimental design methods to optimize the continuous and discontinuous experimental parameters of DLLME and investigated whether DLLME combined with GC-NICI-MS is effective for detecting pyrethroids in agricultural products. The Taguchi design with an L9(34) orthogonal array and response surface methodology were employed to optimize the discontinuous and continuous parameters of the DLLME process, respectively. To validate the performance of GC-NICI-MS after optimized DLLME, pyrethroids in mixed standard solutions at levels ranging from 0.02 to 50.00 µg/L were measured, and the resultant calibration curves were fitted. Adequate linearity was found for the six investigated pyrethroids (r = 0.9908-0.9960). The limits of detection and quantification ranged from 0.005 to 0.035 µg/L and 0.02 to 0.1 µg/L, respectively. The proposed approach simplifies the optimization of parameters compared to reported methods and achieves considerably lower limits of detection. The concept of mixed application based on the dual experimental design method can be applied to other regulated compounds to enhance the safety of agricultural products. The feasibility of the method was confirmed by successfully detecting pyrethroids in 13 types of teas, fruit, and vegetables.