Since 1981, Thermo Scientific Orion ROSS Electrodes have been helping scientists achieve precise results in pH testing and measurements. The original ROSS pH electrode was the first of its kind to use a redox reference system. The redox system provides a stable reading within seconds and increased accuracy by at least 10 times compared to conventional electrodes.

The ROSS system has powered innovations and driven efficiency in ISE and pH testing by scientists and technicians across pharmaceutical, environmental, quality control, and academic labs for 40 years. We think that's something to celebrate and we hope you join us. 

Receive a gift to celebrate 40 years of proven performance

To celebrate the 40th anniversary of ROSS we are giving away a stylus pen with the ROSS signature coil when you answer a short survey. To enter for a chance to win a grand prize pack of three ROSS electrodes of your choice and a ROSS solutions kit simply upload a picture or video of your current electrode in use in the lab. 

Uncoiling the history of ROSS electrodes

The first “Ross” electrode was created in 1980 and introduced into the market in 1981 by Orion Research led then by it’s founders Dr. James Ross and John Riseman. The innovative pH electrode designed by Dr. Ross was based off of redox technology instead of relying on silver chloride, which can precipitate salts into the liquid junction. This system is 10 times more accurate compared to traditional methods and the drift rate is less than 0.002 pH per day. In 1984, Engineer and Glassblower Moshe Hirshberg would design the signature coil for which the ROSS electrode is known, to extend the lifetime of the product up to 2 years, and further cementing the legacy of Dr. Ross. Select your ROSS electrode ›

Celebrating 40 years of ROSS electrodes.



Orion research, known for ISE electrodes introduces a new form of pH electrode using a redox reference system – the ROSS pH Electrode


The signature ROSS coil invented by Moshe Hirshberg was integrated into ROSS pH electrodes


Orion Research merges with Analytical Technologies Inc. and then is acquired by Thermedics Inc., which in 1999 was transferred to Thermo Electron


The Orion ROSS Ultra electrode is introduced to increase the length of reference, helping to provide the electrodes with up to 2 years of life


Thermo Electron and Fisher Scientific merge creating Thermo Fisher Scientific and the Thermo Scientific brand, to which Orion ROSS electrodes belong. The Orion “family” of research and development colleagues mostly remained the same throughout each acquisition and merger, helping to maintain the high quality of the Orion products. 


The first ROSS Ultra Triode electrode is introduced, Cat. No. 8157BNUMD, which combines the measurement capabilities of pH and temperature in one TRIS compatible electrode


A Triode electrode is now offered with a glass body option for sensing slight changes in the activity of certain types of ions, while maintaining full temperature control


The ROSS electrode celebrates 40 years

The ROSS Electrode - Early Days: The New Era of pH Measurement

Retired ROSS Coil Creator and Engineer Moshe Hirshberg writes about his experience working on the pH coil and other innovative projects during his time with Orion Research and Thermo Fisher Scientific. 

Read the blog

What’s the secret to the precision and accuracy of ROSS electrodes?

The distinctive orange coil, which is highly visible in the glass body version of the ROSS electrode, not only gives ROSS electrodes their distinctive look, but is a feature designed to increase electrode lifetime. 

The triodide/iodide system inside the coil provides a chemically stable house for the redox system and protects the electrode from contamination. The first ROSS electrodes were housed in a straight stem, but the product creators were not satisfied with the limitations of this design.

In addition to increasing the life of the electrode, designing a coil into the reference system provides the electrode with two technical advantages over a straight stem design. By significantly increasing the diffusion path to the reference wire, the coil minimizes changes near the reference wire caused by diffusion of fill solution through the reference junction to the inner electrolyte. The effective diffusion path is further increased by incorporating particles or polymers into the inner fill solution.

Find out more about ROSS technology by reading the whitepaper.

Download whitepaper

four images of ROSS electrodes

Explore application specific uses of ROSS pH electrodes and ion-specific electrodes

Measuring pH of Pure Water and Other Low Conductivity Waters

ROSS Ultra triode pH-ATC electrode 

A low resistance junction works best when measuring pure water samples. Avoid a saturated silver electrode filling solution - a precipitate can form on contact with pure water, which may lead to clogging and high resistance in the junction. For this application, the Orion ROSS Ultra Triode combination pH-ATC electrode with capillary junction, which uses silver-free filling solution, is an ideal choice.

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Measuring pH of Water and Wastewater using the Thermo Scientific Orion Dual Star pH/ISE Meter

ROSS Ultra glass-body pH electrode


The use of pH in the treatment of wastewater requires quick, accurate and robust measurement. This application note describes how the Orion Dual Star pH/ISE meter paired with a ROSS Ultra glass-body pH electrode (Cat. No. 8102BNUWP) can help measure the pH levels in water and wastewater.

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Measuring pH in Surface Water

ROSS Ultra Triode pH-ATC electrode

The pH of surface water is a common field measurement. This measurement can be made using a ROSS Ultra Triode refillable combination pH-ATC electrode (Cat. No. 815BNUMD) which will measure both the temperature and pH of the sample with a single probe. The probe provides quick, reproducible results in both fresh and saltwater samples.

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Determination of Sodium in Canned Vegetables by Automatic Multiple Known Addition Titration

ROSS ion selective electrode

Sodium in canned vegetables is determined using the Thermo Scientific Orion Star T930 Ion Selective Electrode Titrator preprogrammed method, Na Veg. The ROSS Sodium Combination Ion Selective Electrode (Cat. No. 8611BNWP) is used to sense the potential due to sodium concentration and determine the amount in the sample. 

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Total Acid Number in petroleum products by automatic titration

ROSS sure-flow pH electrode

Total Acid Number (TAN) in a petroleum product is determined using the Orion Star T910 pH Titrator preprogrammed method T3 TAN. The ROSS Sure-Flow pH Electrode (Cat. No. 8172WP) is used to sense the alkalinity of the petroleum.

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