POTENTIOMETRIC DETECTION OF CARBOXYLIC-ACIDS BY FLOW-INJECTION ANALYSIS USING A TUNGSTEN-OXIDE ELECTRODE

Potentiometric flow injection (PFI) analysis of carboxylic acids based on a tungsten oxide electrode is described. The electrode is shown to offer high sensitivity and a stable baseline for the detection of car boxylic acids. The parameters affecting the electrode response such as the concentration of buffer, the pH and flow rate were studied in det ail. The electrode exhibited a linear response for propionic acid in t he concentration range of 2.5x10(-4)M-5x10(-5)M using a 5x10(-4)M phos phate buffer at pH 6.5 as a carrier. The detection limits were found t o be in the range of 1.0x10(-5)M-5x10(-5)M with a 20 mu l injection.