Diuron and its metabolites in surface water and ground water by solid phase extraction and in-vial elution

A simple and rapid method was developed to determine concentrations of diuron [N'-(3,4-dichlorophenyl)-N,N-dimethylurea] and three of its major metabolites, N'-(3,4-dichlorophenyl)-N-methylurea (DCPMU), 3,4-dichlorophenylurea (DCPU), and 3,4-dichloroaniline (DCA), in ground water and surface water. The analytical method utilizes a 25 mm C-18 Empore disk to quantitatively determine diuron and its metabolites in 100 mL water samples. All analytes are eluted by placing the disk directly into a 2 mL autosampler vial in 1.5 mL of methanol/acetonitrile (50/50) for analysis by HPLC with UV detection. Recoveries from spiked field sample matrices were 98.8 +/- 1.6, 98.1 +/- 4.5, 98.2 +/- 3.6, and 77.8 +/- 4.5% for diuron, DCPMU, DCPU, and DCA, respectively. The method precision, indicated by the relative standard deviation, was typically +/-5%. The method detection and quantitation limits are 0.5 and 1 mu g/L for all analytes except dichloroaniline (1.0 and 2.0 mu g/L, respectively). The concentrations of diuron and its metabolites determined in surface water and ground water samples collected from a field study site are presented.