Determination of phenols in sea water by liquid chromatography with electrochemical detection after enrichment by using solid-phase extraction cartridges and disks

The efficiency and the reproducibility of different solid-phase adsorbents such as C18 cartridges, C18 and poly(styrene-divinylbenzene) (PS-DVB) membrane extraction disks were evaluated for the extraction of phenols from water at μg 1−1 concentration levels. Liquid chromatography with electrochemical detection (LC-ED) was used for the analysis of the organic extracts. A phosphate buffer-acetonitrile-methanol mixture as mobile phase and coulometric detection at + 750 mV were used. High recoveries (70–98%) and good reproducibility (relative standard deviation between 3 and 12%) were obtained using PS-DVB disks, which can be recommended for the enrichment of samples with low concentration of phenols (0.5 μg 1−1). For more concentrated samples (10 μg 1−1), the use of C18 cartridges was preferred because smaller solvent and sample volumes were used and the analysis time was reduced.