The XR43-BA2 from Chauvin Arnoux is a reference electrode with a mercuric sulfate reference system (Hg/Hg₂SO₄), specifically designed for redox potential measurements. It serves as a reference electrode in combination with a measuring electrode (e.g. BAG1 or XAG1) and provides a constant reference potential, which is required for the accurate determination of redox potential. The electrode features a PVC body that protects the internal element, and a ceramic diaphragm that acts as a porous connection to allow the reference electrolyte (saturated potassium sulfate solution, K₂SO₄) to be controlled into the measuring solution, preventing uncontrolled leakage. The connection is made via a banana plug with 2 mm diameter, intended for connection to suitable measuring instruments.

Applications
The XR43-BA2 is particularly used in argentometric dosing applications, where the use of a calomel electrode is not possible due to the reaction of silver ions (Ag⁺) with chloride ions (Cl⁻) forming a silver chloride precipitate (AgCl). In such cases, the mercuric sulfate reference electrode provides a stable and reliable alternative. The electrode is suitable for measurements in laboratory and field applications where precise and reproducible potentiometry is required.

Functions and Equipment in Detail
The electrode consists of a glass tube containing a drop of mercury and a drop of mercuric sulfate (Hg₂SO₄) placed on a platinum wire. This reference element is filled with a saturated potassium sulfate solution, which serves as the electrolyte. The ceramic diaphragm ensures controlled diffusion of the electrolyte into the measuring solution, thereby ensuring stable potential formation. The PVC housing protects the sensitive internal components from mechanical damage and chemical exposure.

Technology Explained Simply
In redox measurements, the potential difference between a measuring electrode and a reference electrode is recorded. The reference electrode, such as the XR43-BA2, provides a constant potential that serves as a reference. The mercuric sulfate system is particularly suitable when the measuring solution contains silver ions, as it does not cause unwanted reactions with chloride ions, unlike calomel electrodes. The use of a banana plug (2 mm) enables a simple and secure connection with measuring instruments that support this connection.

Compatibility and Accessories
The XR43-BA2 is intended for use with measuring electrodes such as BAG1 or XAG1. Suitable accessories, such as a Pepsin/HCl solution (125 ml), are available and can be used for maintenance or calibration of the electrodes. The electrode is part of a system with separate electrodes, particularly suitable for applications where the measuring electrode and reference electrode have different lifespans.

Mounting and Installation
Installation is performed by directly immersing the electrode into the solution to be measured. The banana plug is connected to the corresponding measuring instrument. The electrode is designed for an operating temperature of 0 to 60 °C, making it suitable for a wide range of laboratory and industrial applications. The PVC housing and ceramic diaphragm ensure a robust and long-lasting construction.

Advantages in Operation
The XR43-BA2 provides a stable and reproducible potential reference, particularly in applications with silver ions. The use of a PVC body and ceramic diaphragm increases the electrode’s lifespan and reliability. The simple handling via the banana plug (2 mm) facilitates integration into existing measurement systems. The electrode is suitable for use in various chemical processes where precise redox measurement is required.