# Non-Targeted Screening and Quantitative Analysis of Pesticides and Veterinary Drug Residues in Brassica rapa chinensis Using an Improved Quechers Method Based on Magnetic Materials

## TL;DR

This paper introduces a new method using magnetic materials to detect pesticide and drug residues in a type of Chinese cabbage.

## Contribution

The study presents an improved QuEChERS method using magnetic nanomaterials for efficient residue analysis.

## Key findings

- The method successfully identified over 89.3% of spiked compounds at low concentrations.
- The average recovery rates ranged from 61.7% to 121.6%, indicating high accuracy.
- Nineteen compounds were confirmed and quantified in Brassica rapa chinensis samples.

## Abstract

An improved QuEChERS method based on magnetic nanomaterials was established, and coupled with ultra-high-performance liquid chromatography and a quadrupole electrostatic field orbitrap mass spectrometer, enabling non-targeted screening and quantitative analysis of commonly used pesticide and veterinary drug residues in Brassica rapa chinensis. The combination of magnetic PSA and magnetic multi-walled carbon nanotubes (MWCNTs) was utilized for purification of 121 organic compounds spanning a wide range of polarities. Spiking experiments showed that the developed non-target screening workflow exhibited convincing identification results, with over 89.3% of chemical substances being screened out even at spiking levels as low as 2 μg/kg. The linear ranges of these target substances were between 1 and 200 μg/kg, with determination coefficients all exceeding 0.99. The limits of quantification were between 2 μg/kg and 10 μg/kg. The average recovery rates were in the range of 61.7% to 121.6%. Nineteen compounds were confirmed (meeting all the restriction conditions) and quantified from Brassica rapa chinensis collected from vegetable-planting bases in Jiangsu Province. The results indicated that the magnetic bead-based pretreatment strategy can be utilized for the simultaneous screening and quantitative analysis of pesticide and veterinary drug residues in Brassica rapa chinensis.