Vernier Software and Technology
Vernier Software & Technology
Tech Info Library

I found an ORP electrode that was stored dry. How can I test it to see if the electrode is still working?

The ideal test solution for an ORP electrode is a commercially-produced standard. Many companies sell ORP standards: Hach, Cole Parmer, and Hanna are three examples.
You can also prepare you own test solution. Here are the recipes for two:

Light's Solution: prepare a 0.1 M solution of both ferric ammonium sulfate (NH4Fe(SO4)2 · 12 H2O, also known as ammonium iron (III) sulfate) and ferrous ammonium sulfate ((NH4)2Fe(SO4)2· 6H2O, also known as ammonium iron (II) sulfate) in 1.0 M sulfuric acid. This solution has a potential of 470 - 480 mV.

ZoBell's Solution:
1.4080 g K4Fe(CN)6 · 3H20 (Potassium ferrocyanide)
1.0975 g K3Fe(CN)6 (Potassium ferricyanide)
7.4557 g KCl (Potassium chloride)
Dissolve these chemicals in deionized water and dilute the solution to 1.00 L.
This solution has a potential of 225-235 mV.

Connect your ORP sensor to your platform. Immerse the tip of the ORP sensor in a test standard solution. Allow the ORP sensor about a minute to warm up, and check the reading.

You can also use Light's Solution and ZoBell's Solution to calibrate the ORP sensor, but commercial solutions will be more accurate.

Go to top