Analysis of aromatic sulfonates in water by solid-phase extraction and capillary electrophoresis

The separation of 14 different aromatic sulfonates of environmental concern by capillary (zone) electrophoresis (CZE) is presented. A new off-line solid-phase extraction (SPE) enrichment procedure, that is compatible with CE analysis, was developed, using the styrene-divinylbenzene adsorbent LiChrolut EN. The combined method of SPE and CE allows the determination of aromatic sulfonates in water samples in the low mu g/l range. Separations are performed with a simple sodium berate buffer at pH 9.3. Analytes are detected by UV absorbance and fluorescence emission with a Xe-lamp excitation source, and both principles are compared. The recoveries for most of the sulfonates are >70% for the extraction from spiked tap and river water. The average method precision is <20% for replicate analyses. Very hydrophilic sulfonates cannot be extracted by this method. The detection limit of the combined method. of SPE enrichment and CE analysis is approximately 0.1 mu g/l for 200-ml water samples. The performance of the method was checked with the analysis of river and contaminated seepage water. (C) 1998 Elsevier Science B.V. All rights reserved.