Significant role of supercritical fluid chromatography - mass spectrometry in improving the matrix effect and analytical efficiency during multi-pesticides residue analysis of complex chrysanthemum samples.

As an important "food and drug dual-use" product, chrysanthemums are widely used in both botanical medicine and food applications. However, the misuse of pesticides during chrysanthemum cultivation makes pesticide residue monitoring crucial. The aim of the present work was to address this practical demand for the simultaneous determination of multiple pesticide residues in various species of chrysanthemums. Both the sample pre-treatment and instrumental methods were systematically investigated. Seven chrysanthemum samples were extracted using acetonitrile and purified by dispersive solid-phase extraction with amino-modified multi-walled carbon nanotubes (MWCNTs-NH) and C18 as the cleanup co-adsorbents. After optimizing the amounts of MWCNTs-NH and C18, matrix effects could not be avoided during LC-MS/MS analysis of 112 pesticides, although satisfactory recoveries were obtained. The use of SFC-MS/MS was evaluated, which demonstrated the significant positive role of SFC-MS/MS in reducing the matrix effects during pesticide residue analysis. In addition, the use of SFC-MS/MS permitted a shorter run time and afforded greater analytical efficiency. Method validation was further performed to evaluate the linearity, sensitivity, recovery, and precision of the developed method. Good linearity was observed for 92% of the analytes in the concentration range of 2-250 μg L for all seven of the chrysanthemum samples. The LODs of the 112 pesticides ranged from 0.01 to 31.41 μg L, depending on the sample, while the mean recoveries of all of the spiked pesticides ranged from 81.8% to 102% for concentrations of 20, 50, and 200 μg kg. These results clearly demonstrate the applicability of the developed method for the simultaneous determination of multi-pesticides in various chrysanthemum samples.