Fabrication of poly-dopamine-modified magnetic nanomaterial and development of integrated QuEChERS method for 122 pesticides residue analysis in fruits

A rapid and accurate integrated QuEChERS method was established for the determination of multi-pesticide residues in fruits. Poly-dopamine-modified magnetic nanomaterial (Fe3O4-pDA) was homemade and characterized. The prepared Fe3O4-pDA has the functional group of absorbing the saccharides, and can be used as co-adsorbent with 3-(N, n‑diethyl amino) propyl trimethoxy-silane (PSA) in the developed integrated QuEChERS method to purify the fruit matrix, thus achieve the accurate determination of multi-pesticides residue. Grape was used as the representative sample to explore the influence of the salting out agent and each purification adsorbent on the pesticide recoveries. Under the optimized conditions, the proposed method showed good linearity for 92.6% of pesticides in the concentration range of 1-150 μg L-1 with method limit of quantitative (mLOQs) ranged from 10 to 18 μg kg-1. Spiked recoveries experiments were performed on four kinds of grapes and other fruits (apple, watermelon, pear, jujube and peach), in which satisfactory recoveries and precision were obtained for most of the pesticides. Meanwhile, comparison experiments also verified this method was superior to the traditional QuEChERS method in terms of convenient operation, high efficiency and low reagent consumption. The further real sample analysis was performed using this method, and the overall detection rate was 52%, while 2% of samples were exceeding the maximum residue limits. All results confirmed that the proposed method could be used for the rapid, simple, low-costing and effective analyses of trace multi-pesticides residue in fruit samples.