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 μg/l range. Separations are performed with a simple sodium borate 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 μg/l for 200-ml water samples. The performance of the method was checked with the analysis of river and contaminated seepage water.