pH Electrolytes and Maintenance Solutions

Quality Solutions to Store and Maintain Your Sensor

pH electrolytes and maintenance solutions are standards that ensure the sensor is protected and measures accurately. The sensor is the main actor of the measurement, requiring, therefore, special care and attention. METTLER TOLEDO offers the necessary pH maintenance and storage solutions along with quality electrolytes to ensure the sensor is ready to measure and provides accurate readings. Offered in a variety of sizes, choose between 25 mL or 250 mL single- or six-pack options.

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FAQs

What is a pH reference electrolyte?

The reference electrolyte ensures a stable signal transmission. Due to its high ion concentration, the reference electrolyte conducts the electronic signal from the reference element (mainly Ag/AgCl) to the measured medium. It thus closes the electronic circuit of the pH measurement system.

 

What is the difference between refillable liquid and gel electrolytes?

Electrodes with refillable liquid reference electrolyte will have a longer life, less risk of reference contamination, and faster response time than electrodes with gel electrolyte. However, sensors with gel electrolyte are easier to maintain.

 

How should I store my sensor?

pH glass sensors need to be kept moist at all times. If an electrode dries out during storage, a regeneration procedure is required to restore the hydrated glass layer and the reference junction in order to make the sensor operable. As a general rule, store your pH sensor in the same solution as the reference electrolyte of the sensor. In most cases, InLab® Storage solution can be used. Sensors with a bridge electrolyte should be stored in the electrolyte of the outer electrolyte compartment.

 

How should I clean my pH sensor?

Your pH sensor should be cleaned regularly. Reduced slope and/or offset or slow response time are an indication that your sensor needs cleaning. Fats, oils, and grease should be cleaned with a non-ionic surfactant solution or methanol. Proteins should be cleaned with a Pepsin-HCl Cleaner solution. After cleaning, rinse the sensor with deionized water, recondition it in 3M KCl and then store it in store in the InLab® Storage Solution.

 

What is the expected outflow of the reference pH electrolyte?

  • 1 mL per 24 hours for electrodes with a ceramic diaphragm (e.g., InLab® Routine)
  • 3 mL per 24 hours for electrodes with a sleeve diaphragm (e.g., InLab Science)
  • Electrodes with a solid-state electrolyte and open junction (e.g., InLab Expert) have no outflow but only "exchange" of ions via diffusion

 

Does the inner pH electrolyte level in a bridge electrode need to be greater than the outer pH electrolyte?

Yes. If the bridge electrolyte has a higher filling level, then it flows into the chamber with the pH reference electrolyte (due to the higher pressure at the inner junction). This changes the composition and is not pure 3 mol/L KCl anymore. The reference signal of the electrode depends on the solution's composition, hence, the measured potential between measuring half-cell and reference half-cell changes due to it.

 

Is crystallization of the electrolyte and salt deposits dangerous?

Salt buildup and crystallization of KCL are not harmful to the electrode and do not inhibit its performance. However, it should be removed before measurement.