Analysis of organic pollutants in water at trace levels using fully automated solid-phase extraction coupled to high-performance liquid chromatography

A method has been developed for the determination of trace levels of 32 pesticides, 19 explosives and 16 polycyclic aromatic hydrocarbons (PAH) in water in three individual steps. Solid-phase enrichment (SPE) is coupled to high-performance liquid chromatography (HPLC) with a fully automated system. The organic pollutants are enriched on reusable cartridges packed with adsorbent materials: pesticides and explosives on a mixed bed of divinylbenzene-ethylvinylbenzene copolymers (LiChrolut EN(R)) and perfluorinated polyethylene (PolyF(R)), and polycyclic aromatic hydrocarbons on C-18-modified silica (Zorbax(R) ODS1). Thermally assisted desorption (TAD) has been shown to increase the recovery of analytes significantly. As all enriched analytes are transferred to the detector, only fifty millilitres of sample is needed for each single on-line analysis, compared with at least a litre for conventional methods. The separation of the enriched organic analytes is performed on specialized HPLC columns based on reversed-phase materials. The limits of detection of the system employed were found to be below 100 ng L-1. Use of fluorescence detection for the polycyclic aromatic hydrocarbons resulted in limits of detection in the upper pg L-1 range. The k values, number of theoretical plates, the recovery rates and the limits of detection of this method for fast screening of organic pollutants from three fifty-millilitre aqueous samples are described.