Determination of phenolic compounds at low mu g 1(-1) levels by various solid-phase extractions followed by liquid chromatography and diode-array detection

An off-line solid-phase extraction was carried out to determine thirteen phenolic compounds, which included eleven EPA priority phenols, using reversed-phase liquid chromatography and diode-array detection. Two different sorbents, carbon and a highly cross-linked styrene-divinylbenzene copolymer, were compared for the preconcentration process. To increase the retention of the most polar compounds, mainly phenol, tetrabutylammonium bromide was used as an ion-pair reagent in the extraction system. Better recoveries were obtained for the copolymer sorbent and the performance of the method was tested with tap and Ebro river water. Recoveries higher than 90% were obtained for all compounds when a 500-ml sample was preconcentrated using the optimum conditions found with the copolymer sorbent. The R.S.D. for a river water sample spiked at 1 mu g l(-1) was lower than 10% (n = 4) and the detection limits were between 65 and 100 ng l(-1).