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DOI: 10.1039/A702338C (Paper) Reference Section for: Analyst, 1997, 122, 889-894

Determination of Phenoxy Acid Herbicides From Aqueous Samples by Improved Clean-up on Polymeric Pre-columns at High pH

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René B. Geerdink, Sylvia van Tol-Wildenburg, Wilfried M. A. Niessen and Udo A. Th. Brinkman

Abstract

An improved procedure for the determination of phenoxy acid herbicides in environmental water samples is reported. The procedure consists in solid-phase extraction (SPE) of 60 ml water samples on a polymeric pre-column at pH 2.8, a clean-up step at high pH and subsequent desorption and ion-pair LC separation at pH 8.8. The main improvements are in the basic clean-up step and in the LC eluent composition. The release of compounds which are electrostatically bound to the precolumn is favoured by a washing step with 0.1 mol l-1 sodium hydroxide solution. As regards LC, gradient elution is applied using solvents with low buffer and ion-pairing concentrations. The detection limits for the phenoxy acids (UV detection at 232 nm) are 5–20 ng l-1 for tap water samples. At the 0.1 µg l-1 spiking level, the RSD is 6% (n = 7) and the recoveries are better than 83% for all analytes. The long-term reproducibility typically has RSD values of 5% (n = 7). The method was successfully tested on water samples from various origins, and the results obtained with the present on-line SPE–LC–UV procedure were found to compare well with those obtained with procedures involving SPE combined off-line with GC–MS or flow injection MS–MS.

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