A NEW DERIVATIZATION AND PRECONCENTRATION METHOD FOR DETERMINATION OFTRACE PHENOLS IN NATURAL-WATER BY HPLC

A simple and highly effective pre-column on-line concentration method for determination of phenols by HPLC was developed. In the first step, phenols in the sample solution were converted to UV-absorbing derivat ives by coupling with 4-sulfobenzenediazonium salt at pH 10.5, and ion -associates of the 4-sulfobenzeneazo derivatives were formed with tetr adecyldimethylbenzylammonium-chloride at pH 5.0. The ion-associates we re collected on a PTFE membrane filter (6 mm phi, 0.5 mu m pore size) in a line-filter placed on a 6-way injection valve. The sample size (i njection) was up to 3 cm(3) The separation was carried out with a ODS column (Tosoh, TSKgel ODS-120T, 4.6 i.d.X250 mm) (column temperature 3 5 degrees C) and 37.5% acetonitrile/62.5% 8.0X10(-3) mol dm(-3) acetat e buffer solution (pH 4.6) containing 1.6X10(-4) mol dm(-3) tetradecyl dimethylbenzylammonium-chloride as the mobile phase (flow rate, 1.0 cm (3) min(-1)). A UV detector (352 nm) was used for monitoring. Eight ph enols including phenol, m-chlorophenol, o-, m-cresol, o-, m-ethylpheno l, 2,3- and 2,5-xylenol were successfully sepa rated and determined. C alibration plots for each of the phenols were linear up to 50 ng Detec tion limits ranged between 40 ng dm(-3) (phenol) and 2 mu g dm(-3) (2, 5-xylenol). The method was used for the determination of phenols in ri ver water.