Evaluation of matrix effects for pesticide residue analysis by QuEChERs coupled with UHPLC-MS/MS in complex herbal matrix

Matrix effects (MEs) can heavily affect the accuracy and reproducibility of a pesticide residue analysis method, especially in complex matrices such as herbs. Therefore, it is of great importance to assess MEs of pesticides in herbal matrices. In this research, the MEs of 28 pesticides and their metabolites in five types of herbs representing different medicinal parts were evaluated by UHPLC-MS/MS analysis after QuEChERs pretreatment. Suppression MEs were found for most organophosphorus and carbamate pesticides while enhancement MEs were observed for sulfonylurea. Besides, stronger inhibition effects were observed for early or late elution pesticides and in matrices of Lonicerae japonicae flos and Perillae folium. Some pesticides were observed with enhancement MEs in Astragali radix. These results indicated that MEs were mainly affected by the retention time of the analytes, the ionization mode of the precursor ions, the overall structure of the compounds, and the chemical composition of the matrices.