Determination of alkylphenols in mineral water contained in PET bottles by liquid chromatography with coulometric detection

An HPLC method utilizing reversed-phase chromatography coupled with coulometric detection was developed for the determination of alkylphenols in mineral water. Alkylphenols in water samples were extracted with ethyl acetate. The alkylphenols were completely separated by an ODS column with acidic mobile phases and detected with a dual coulometric detector. The first electrode set at 400 mV was used for sample clean up, whereas the second one set at 650 mV was used for analytical purposes. The limits of detection (signal-to-noise ratio of 2) of eight alkylphenols tested were in the range from 0.25 pmol (BPA) to 1.0 pmol (p-NP) on chromatograms. The proposed procedures were applied to mineral water in PET bottles. All nine samples contained both bisphenol A (BPA) and p-nonylphenol (p-NP). The concentrations of BPA and p-NP calculated from calibration curves were 2 - 10 ng/l and 19 - 78 ng/l, respectively. The concentrations were essentially the same before and after heating at 50 degreesC for 8 h.