Determination of NO3- ions with a selective electrode (potentiometry)
Constitution of the electrode
As with the calcium ion selective electrode, this electrode consists of:
- an Ag/AgCl reference electrode (chloride silver wire) connected via a connecting head (part A) to a conducting wire;
- A plastic body containing at its end a PVC (polyvinyl chloride) membrane containing an ionophore capable of almost selectively complexing the nitrate ions NO3- (active part of the electrode);
- An internal KNO3 filling solution supplied by the manufacturer.
![Diagram of the electrode construction. The connecting head (part A) at the top is extended by the electrode body (part B). The Ag / AgCl reference electrode is soaked in a filling solution. At the base is a PVC membrane containing an ionophore.](/resources/images/fiches/aliments/analyse-eau/en/eau106.png)