Simultaneous Determination of Traces of Herbicides in River Water

Abstract

A liquid chromatography tandem-mass spectrometry (LC/MS/MS) method has been developed for the highly sensitive determination of herbicides, pyraclonil, daimuron, pyrazosulfuron-ethyl and benzofenap, in river water. River water was filtrated with a glass fiber filter, followed by solid-phase extraction with a styrene-divinylbenzene copolymer with a nitrogen-containg polar group-methacrylate cartridge. Positive electrospray ionization (ESI-positive) was used to ionize herbicides, and the determination was performed by the selected reaction monitoring (SRM) method. The method detection limit (MDL) and the method quantification limit (MQL) are 0.78 ng L⁻¹ and 2.0 ng L⁻¹ for pyraclonil, 0.26 ng L⁻¹ and 0.67 ng L⁻¹ for dimuron, 0.44 ng L⁻¹ and 1.1 ng L⁻¹ for pyrazosulfuron-ethyl, 0.45 ng L⁻¹ and 1.1 ng L⁻¹ for benzofenap. The average recoveries from river water spiked with the herbicides; those concentrations were the same as MQL, and are 99%, 100%, 110% and 54%, respectively. All compounds except for pyrazosulfuron-ethyl were detected in river water collected after herbicide application.