We are determining manganese concentration by potentiometric titration using a platinum wire spiral/ tungsten wire couple as electrodes in combination with sodium pyrophosphate, as described in the standard method. We are obtaining good results with this method.
Recently, we received an automatic potentiometer Titrino Plus 848, which has a combined platinum ring electrode, supposedly equipped with Ag / AgCl reference electrode element. Work on a new device shows that we are getting higher concentrations of manganese compared to the paired platinum/tungsten electrode method, in addition, we are observing irreproducible results with this machine.
I would be grateful to hear your opinion about the acceptability of using this Pt ring ORP electrode in the potentiometric titration of manganese for arbitration purposes, while the standard procedures indicate only the use of platinum-calomel, platinum-platinum or platinum-tungsten couples.