Evaluation and characterization of a commercial immunosorbent cartridge for the solid-phase extraction of phenylureas from aqueous matrices.

The behavior and main characteristics of a commercial immunosorbent (IS) cartridge for the solid-phase extraction of phenylureas are determined in this work. The measured capacity for the analyte-antigen (isoproturon) in a new cartridge is 215 ng and, after more than 100 adsorption-desorption cycles, the remaining capacity still is approximately 70 ng, demonstrating the good stability of the bonded antibody and the interesting possibility of extensive cartridge reuse. Only isoproturon and diuron are specifically retained in this sorbent. The weak nonspecific retention of other pesticides, including other phenylureas, can be avoided by increasing the sample volume during the loading step. Thus, a very selective and sensitive method for the determination of isoproturon and diuron in natural and potable waters is developed by loading a 50-mL sample adjusted to pH 7.4 in the IS cartridge, eluting with methanol-water (60:40, v/v), and analyzing the eluate by high-performance liquid chromatography with UV detection. The clean chromatograms, low detection limits (approximately 0.1 micro g/L), and good precision (< 5%) obtained with this rapid and simple method demonstrate that immunoaffinity extraction can be an excellent alternative for sample preparation in the environmental monitoring of particular pesticides in water matrices.