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.
The correct pH electrolyte will minimize potential junction errors and provide optimum temperature and time responses. The proper electrolyte to use is written on the sensor shaft. The pH electrolyte must be refilled or replaced regularly to achieve good electrode performance. Our pH sensors come with a special wetting cap that makes refilling easy.
Electrodes should always be stored in aqueous and ion-rich solutions. The InLab® storage solution provides optimal conditions for sensors during the time between measurements, be it short- or long-term storage.
Using a dirty electrode is one of the typical sources of error in pH measurement. Whenever rinsing with deionized water is not sufficient, a special cleaning solution can be used to remove sample residues. Depending on the contamination, Pepsin-HCl or Thiourea is recommended.
For high accuracy, uncontaminated solutions are of utmost importance. For pH electrolyte solutions, we offer 25 or 250 mL single- or six-pack options. pH maintenance solutions are also offered in small bottles, enabling easy handling and reducing the contamination risk.
METTLER TOLEDO provides entire electrochemistry systems—from meters and sensors to calibration solutions and software. Benefit from a broad portfolio, choose the right sensor for your application, and maintain and store it correctly with the proper pH electrolytes and maintenance solutions.
We support and service your measurement equipment through its entire life-cycle, from installation to preventive maintenance and calibration to equipment repair.
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.
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.
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.
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.
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.
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.