Impedance Study of Drinking Water and Tastants Using Conducting Polymer and Metal Electrodes

In this study the sensing capabilities of a combination of metals and conducting polymer electrodes for drinking water and dissolved tastants using an AC-impedance mode in frequency range 10 to 10 Hz at 0.1 V potential has been carried out. Classification of seven different bottled and municipal drinking water samples along with various tastants dissolved in DI water (DI water) for KCl (5mM) (salty), HCl (5 mM) (sour) quinine (0.1 mM) (bitter), sucrose (5 mM) (sweet), black tea liquor, black tea liquor with sucrose (2% sugar solution), and a bottle of “packed” orange juice has been made using six different working electrodes in a multi electrode setup using PCA. Working electrodes of Platinum (Pt), Gold (Au), Silver (Ag), Glassy Carbon (GC) and conducting polymer electrodes of Polyaniline (PANI) and Polypyrrole (PPY) grown on an ITO surface potentiostatically have been deployed in a three electrode set up. The impedance response of these water samples using number of working electrodes shows a decrease in the real and imaginary impedance values presented on nyquist plots depending upon the nature of the electrode and amount of dissolved salts present in water/tastants. The different sensing surfaces allowed a high cross-selectivity in response to the same analyte. From PCA plots it was possible to classify drinking water in 3-4 classes using conducting polymer electrodes; however tastants were well separated from the PCA plots employing the impedance data of both conducting polymer and metal electrodes.