Abstract:

Objective To construct a matrix effects（ME） evaluation method for fruit pesticide residues based on ultra-performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS），ensuring the accuracy of the test results. Methods Blank matrices of five fruits（plum，guava，litchi，longan，and red bayberry） were selected. After extraction and purification using the quick，easy，cheap，effective，rugged，safe（QuEChERS） method，six sets of calibration curves were established using acetonitrile and matrix-matched standards. The matrix effects of 20 organic pesticides were assessed within the concentration range of 5-200 μg/L. Results The 20 pesticides exhibited good linearity（r>0.998） in the range of 5-100 μg/L. Matrix effect analysis revealed that for plum，suppression predominated，with 75% of pesticides suppressed and 55% showing strong suppression，possibly related to high organic acid content；Whereas five pesticides including dimethomorph，showed enhancement effects，ranging from 2% to 28%. Both guava and litchi showed 70% enhancement effects（ME up to 115%），with 75% of effects being negligible；Dinotefuran exhibited moderate suppression in both. In longan，95% of pesticides showed enhancement effects（ME up to 174%），with 40% negligible. In red bayberry，60% showed enhancement effects（ME up to 92%），while dinotefuran and carbendazim exhibited moderate suppression. Matrix effects differed significantly among different fruit types. Conclusion The matrix effects of 20 pesticides vary significantly across five types of fruits，with no fruit exhibiting uniformly weak matrix effects. It is recommended to prepare standard curves using the same or similar blank matrices for qualitative and quantitative analysis. This approach can mitigate recovery rate deviations in multi-pesticide residue analysis.

Key words: Matrix effects, Ultra-performance liquid chromatography-tandem mass spectrometry, Fruits, Pesticide residues