Application of dispersive liquid-liquid microextraction for the determination of phenylurea herbicides in water samples by HPLC-diode array detection.

A simple dispersive liquid-liquid microextraction method combined with HPLC-photodiode array detection has been developed for the determination of phenylurea herbicides in water samples. The herbicides studied included tebuthiuron, diuron, propanil, fluometuron, siduron, linuron, thidiazuron, and diflubenzuron. Several factors influencing the extraction efficiency of the studied compounds, such as extraction and disperser solvent type and their volumes, co-solvent type and its fraction, and ionic strength were investigated and optimized. Under the optimum extraction conditions, the calibration graphs were linear in the range of 0.2-200 mug/L for target analytes. The enrichment factors were between 11 and 118. The LOD were in the range of 0.01-0.5 mug/L (S/N=3). The relative standard deviations obtained ranged from 3.0 to 7.8% (n=5).