Determination of multi-pesticide residues in agricultural products with a modified QuEChERS process based on magnetic biochar from coconut clothing.

In this study, the magnetic biochar material derived from coconut clothing was firstly successfully synthesized by in-situ polymerization method and applied as QuEChERS adsorbents for extracting multi-pesticides. The obtained magnetic coconut-clothing biochar (MCCBC) presented alveolate structure with abundant large irregular pores. The Fe ₃ O ₄ particles was obviously attached on the surface of biochar. Under the optimized conditions, the modified QuEChERS process based on MCCBC coupled with HPLC-MS/MS for simultaneously extracting and determining 12 pesticides (organophosphorus insecticides and strobilurins) from different agricultural products (tomato, cucumber, cabbage, carrot, peach, pear, grape, apple) was established. After pretreated by MCCBC, most of pesticides had weak matrix effect. This proposed method showed good linearity (2-250 ng g ^-1 ) with R ²  ≥ 0.9915, and the limits of detection and the limits of quantification were in the range of 0.01-2.67 ng g ^-1 and 0.03-8.91 ng g ^-1 , respectively. The acceptable recovery was between 71.1 % and 114.0 % with relative standard deviations from 0.31 % to 13.94 %. These results fully demonstrated that the developed method was efficient for simultaneously extracting and determining organophosphorus insecticides and strobilurins in complex agricultural matrix, possessing obvious advantages of higher sensitivity, easier operation and good feasibility. More importantly, this study provided a useful strategy for magnetizing biochar, and the novel biochar from coconut clothing was also introduced as potential adsorbent for other trace organic pollutants.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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