Potentiometric Detection of Metal Ions Separated by Liquid Chromatography Using a Tungsten Oxide Electrode

The use of a tungsten oxide sensor for the potentiometric detection of metal ions separated by liquid chromatography is described. Separation of metal ions such as Fe3+, Fe2+, Cu2+ and Pb2+ was performed by ion chromatography using a mobile phase containing 25 mM sodium tartrate/2 mM ethylenediamine at pH 3.8. Calibration plots were linear in the range 0.5 to 3.5 mM. Potentiometric detection was also applied to ion-interaction chromatography. The results showed that separation of metal ions was improved and the detection limits for the test metals in the range of 0.5-5 nmol were obtained in the presence of sodium citrate/1-octanesulfonic acid at pH 3.0. The potentiometric detection described in this article is shown to have advantages in terms of low cost, simplicity and sensitivity.