Design of the fluoride ion-selective electrode as tubular detector for flow injection analysis

Design of the fluoride ion-selective electrode (FISE) as the tubular detector used in the now injection analysis (FIA) has been described. Among other things, this design makes it possible to use various internal contacts. The effect of pH on peak height and detection limit in the pH range from 2.8 to 8.0 has been examined. The effect of now rate and sample injection volume on peak height and range of linear response has also been examined. The flow rates range from 0.56 mL/min to 4.05 mL/min, while the injection volumes are 100 and 200 mu L. The optimum conditions are carrier solution (0.1 M KNO3 buffer pH 4 and 10(-6) M NaF), flow rate 1.54 mL/min and sample injection volume 100 mu L. Applicability of the FISE as the tubular detector in determination of Fe(III)-ions and Al(III)-ions by now injection analysis has been examined at pH values of 2.8 and 3.4.