Design and synthesis of amphiphilic carboxyl-functionalized magnetic polymer microspheres for fast determination of paraquat and its four metabolites in human urine samples prior to ultra-high performance liquid chromatography-high resolution mass spectrometry

•Synthesis of core-shell Amphiphilic-MPs-COOH in a controlled manner.•High cleanup efficiencies toward PQ and its metabolites in urine samples were obtained.•Effect of hydrophilic monomer NVP and functional monomer 4-VBA was significant.•Confirming for PQ poisoning based on both PQ prototype and its four metabolites.