Published:Journal of Chromatographic Science,
ISSN 0021-9665Volume
41, Number 9, October 2003, pp. 480-488
Evaluation and Characterization of a Commercial Immunosorbent
Cartridge for the Solid-Phase Extraction of Phenylureas from Aqueous Matrices
Luz E. Vera-Avila, Laura Rangel-Ordoñez, and Rosario
Covarrubias-Herrera
Departamento de Química Analítica, Facultad de Química,
Universidad Nacional Autónoma de México, 04510 México
D.F., México
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 (~ 0.1 µg/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.
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