BIVOLTAMETRIC TITRATIONS USING ELECTRODES WITH INNOVATIVE GEOMETRY

Electrodes with different surface areas were investigated for the dete rmination of reversible, quasireversible, irreversible or electroinact ive substrates. Two kinds of electrodes were constructed, a helical el ectrode with a given asymmetry and a platinum array electrode with a v ariable area. These electrodes were applied for the cerimetry of ammon ium iron(II) sulfate and for the bromatometry of various organic subst ances. The theoretically derived effects on the shape of the voltametr ic titration curve are verified experimentally. It is possible to shar pen one side of the peak and to broaden the other side, depending on t he system and the side of the peak one is interested in. It is possibl e to improve the bivoltametric determination of hydroquinone, benzocai ne and sulfaguanidine by bromatometry by the directed employment of el ectrodes of different areas. For the bromatometric determination of el ectrochemically irreversible substrates the use of the electrode geome tries proposed is a way to obtain a sharp bend and a steep decrease of titration curves with low values of the constant current which is a b asic requirement for the accuracy.