Flow cell contact test

Applies to

Electrochemical flow cell of wall jet type

Summary

Testing for a short circuit between the working electrode (WE) and auxiliary electrode (AUX). If so, the cell will have high noise and background current, and a poor signal-to-noise ratio.

Fig. 1. Working electrode block of a SenCell. The WE is isolated from the AUX, there should be no contact between the two.

Cause

Several causes:

1. wear and tear
2. heating of the cell
3. ultrasonic cleaning (results in heating)

Diagnosis

AUX and WE should be completely isolated. This is tested by applying a voltage over both electrodes and measuring the (zero) current.

1. The cell is switched off, disassembled
2. Clean the cell with demi water and carefully dry the cell
3. WE and AUX are connected to the cell cable, with the REF connected to AUX
4. Set the Ecell (cell potential) to 800 mV, range to 10 nA, and switch on the cell
5. Make sure electrodes are dry and do not make any external contact
6. The I cell must be 0.00 ± 0.05 nA, if significantly larger there is an internal leakage.

Fig. 2. Wiring for flow cell contact test.

Remedy

In case of contact between WE and AUX contact your supplier. The cell must be repaired (if possible) or replaced.