An analysis of residue alkylphenols and bisphenol A using liquid chromatography-tandem mass spectrometry

Bisphenol A (BPA) and alkylphenols (APs) such as 4-tert-octylphenol (4-t-OP) and mixture of nonylphenol isomers (iso-NP) are frequent contaminants of various environmental analyses. Analyse of various blanks is a serious problem in the residue analysis. Secondary contamination of analysed samples can come from laboratory air, septa vials, solvents and other chemicals used. Plastic tubes and connections could be another important source of sample contamination. This can be a problem especially in determination of alkylphenols and bisphenol A at low environmentally relevant concentrations. The analytical method for determination of residues of pollutants in water samples using solid phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is presented here. In principle, alkylphenols can be analysed without derivatization. However, pre-column derivatization with 5-(dimethylamino) naphthalene-1-sulfonyl chloride (dansylchloride, DNSC) improves the sensitivity and selectivity of LC-MS/MS analysis. The instrumental blank for all compounds is under the limit of detection (LOD). The system contamination was maintained about 0.5 ng (reagent blank), and below 0.05 mu g/L for the glass SPE columns and below 0.1 mu g/L for the plastic columns (procedure blank).