Comparison of different sorbent materials for on-line liquid-solid extraction followed by liquid chromatographic determination of priority phenolic compounds in environmental waters

A comparative study of the performance of four sorbents [PLRP-S, LiChrolut EN, Isolut ENV and porous graphitic carbon(PGC)] for on-line liquid-solid extraction (LSE) followed by liquid chromatography (LC) of phenolic compounds in water was carried out. Better breakthrough volumes were obtained when working with LiChrolut EN and Isolute ENV than the other sorbent materials. Recoveries in ground water were in the range 55-105% and detection limits down to 0.1 mu g/l were achieved, except for catechol and 2-amino-4-chlorophenol. A few differences were found when comparing sorbents from various suppliers, which was attributed to their different physico-chemical properties. PGC gave good results only for aminophenols. Binding phenomena among phenols and humic substances were detected, leading to interferences in the determination The procedure was validated by participating in various inter-laboratory exercises using ground water samples distributed by Aquachek (WRC, Medmenhan, UK), containing phenols at levels ranging from 0.1 to 5 mu g/l.