The reference electrode is used with a standard glass pH electrode as a pair to make measurements of pH. The reference provides a stable and constant reference potential independent of the chemical composition of the various samples to be measured.

One of the major design differences between reference electrodes is the type of chemical half-cell that the electrode uses for a reference element. There are two major types:

Calomel Reference (Hg/Hg₂Cl₂)
Temperature Range: -5°–80°C.

The calomel reference is a very stable half-cell that is ideally suited for use with TRIS buffers and sample solutions containing proteins and other biological media. Also recommended where samples contain metal ions, sulfides, or other substances that will react with Ag/AgCl reference cells.

Silver/Silver Chloride Reference (Ag/AgCl)
Temperature range:
-5°–100°C Continuous use
-5°–130°C Intermittent use.

The Ag/AgCl reference is also a very stable half-cell that has a much higher working temperature than the calomel reference. Recommended for all applications except those involving TRIS buffer, proteins, metal ions, sulfides or other substances that will react with either Ag or AgCl.

Standard packed reference cells are for general laboratory use. Recommended for majority of pH and titration measurements. Features porous ceramic wick with moderate flow rate. Side spout allows reference to be pressurized through a septum cap.

Featuring a refillable chamber that acts as a salt bridge between the reference cell and the liquid sample. This intermediate salt bridge can be filled with an electrolyte that least interferes with the user's measurements. Most commonly used to avoid Ag⁺ and Cl^- contamination of the sample. Features porous ceramic wick with moderate flow rate. Salt bridge filled with 10% KN0₃ for shipment.

Primarily there are four things we need to know in order to correctly fill your order.

1. Electrode Model Number — Each electrode has a ten character model number.

2. Cable Type — All lab electrodes are equipped with Type A, low noise, 3 mm, coaxial cable. Place the A after the electrode number.

3. Cable Length — The cable length is expressed in feet immediately after the cable type. Example: "-A03" stands for a three foot cable which is standard for all electrodes in this catalog. Follow model numbers by a"-DK" for a threaded electrode cap.

4. Connector — The cable length is followed by a two letter designation for the proper connector. All connectors are available. If you do not see what you need on this page, give us the make and model numbers of your pH meter and we will supply the proper connector.

Example: C13PIA-521-AO3SC