Determination of phenoxyacid herbicides and their phenolic metabolites in surface and drinking water

An evaluation was made of the feasibility of using reversed‐phase liquid chromatography/tandem mass spectrometry with an electrospray interface (LC/ESI‐MS/MS) to measure traces of phenoxyacid herbicides and their metabolites in surface and drinking water samples. The procedure involved passing 0.5 L of river and drinking water samples through a 0.5 g graphitized carbon black (GCB) extraction cartridge. Recovery was higher than 85% irrespective of the aqueous matrix in which the analytes were dissolved. A conventional 4.6‐mm i.d. reversed‐phase LC C‐18 column operating with a mobile phase flow rate of 1 mL/min was used to chromatograph the analytes. A flow of 200 µL/min of the column effluent was diverted to the ESI source. The limits of detection (signal‐to‐noise ratio = 3) of the method for the pesticides considered in drinking and surface water samples are less than 0.1 ng/L for phenoxyacid herbicides, and about 5–10 ng/L for their metabolites (2,4‐dichlorophenol and 4‐chloro‐2‐methylphenol). Copyright © 2001 John Wiley & Sons, Ltd.