Objective To establish a method for rapid determination of the residues of carbofuran, dichlorvos, dimethoate, and malathion in drinking water by magnetic dispersive solid-phase extraction combined with ultra-performance liquid chromatography-tandem mass spectrometry using synthesized magnetic carbon material as the adsorbent.

Methods Magnetic carbon material was added to the drinking water sample for dispersive solid-phase extraction, and the solution was discarded under external magnetic field. Then methanol was used to desorb the analytes and the eluent was separated by a C₁₈ column after passing through the filter membrane and was detected by multiple reaction monitoring with electrospray ion source in positive ionization.

Results Carbofuran, dimethoate, and malathion showed a good linear relationship within the range of (0.10-50.0)μg/L, and dichlorvos showed a good linear relationship within the range of (0.20-100.0)μg/L, with a correlation coefficient of 0.999 0 and above. The method had a limit of detection of (0.017-0.050)μg/L and a limit of determination of (0.06-0.17)μg/L. The average recovery at three spiking levels ranged from 88.0% to 105.7%, with a relative standard deviation of 2.0%- 12.1% (n = 6). The magnetic material still had good adsorption performance after repeated use for 10 times.

Conclusion This method is simple, efficient, and accurate and can be used to determine the residues of carbofuran, dichlorvos, dimethoate, and malathion in drinking water.