On-Line Dialysis-Column Liquid Chromatography for the Determination of Polar Pesticides in Water Samples Containing Humic Substances

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Abstract
The potential of the on-line combination of dialysis, for the removal of interfering humic substances from environmental samples, and trace enrichment on a precolumn packed with C18-bonded silica for the determination of polar pesticides by column liquid chromatography with UV detection is investigated, using six phenylurea herbicides as model compounds. The influence of the membrane material, thickness and molecular weight cut-off value, the configuration of the system-i.e. planar or hollow-fibre membranes-and, especially, the sample volume on analyte recovery and removal of humic Substances is studied. Systems which allow the determination of the test compounds at the 1.0 μg/1 level in river and lake water and at the 0.1 μg/l level in tap water are presented.