Laboratory pH Sensor

Accurate pH Electrodes and Probes for a Wide Range of Laboratory and Field Applications

A laboratory pH sensor is used to determine the alkalinity or acidity of a sample both in the lab and in the field. METTLER TOLEDO offers reliable pH electrodes and probes that provide accurate readings for a wide range of applications in industries such as pharma, biotechnology, F&B, or chemical. We have a broad portfolio that includes built-in temperature probes and low-maintenance options, and our Intelligent Sensor Management (ISM®) enhances data security and makes handling easy.

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Can METTLER TOLEDO's laboratory pH sensors be used to measure the pH of aqueous solutions only?

pH is a property associated predominantly with aqueous solutions. Therefore, conventional sensors designed to measure pH in aqueous media fail to measure pH accurately in non-aqueous solutions. However, our specialized InLab® Sensors such as InLab Science Pro-ISM are designed for these types of specialized applications, making it possible to measure the pH of non-aqueous solutions, organic solvents, solids, and semi-solids with ease. Therefore, METTLER TOLEDO's pH meters and sensors can be used to measure the pH of a wide variety of samples.


What is the expected flow rate of a reference electrolyte from the lab pH sensor?

The expected outflow of a reference electrolyte is:

a. 1 mL per 24 hours for electrodes with a ceramic diaphragm (e.g. InLab® Routine)
b. 3 mL per 24 hours for electrodes with a sleeve diaphragm (e.g. InLab Science)

Electrodes with solid state electrolyte and an open junction (e.g. InLab Expert) have no outflow but only "exchange" ions via diffusion.


What are the advantages of the Argenthal reference system for laboratory pH sensors?

In order to prevent the stripping of Ag from Ag wire, the ARGENTHAL™ reference element was created. The specialized ARGENTHAL reference element consists of a small cartridge filled with AgCl particles that provide the silver ions for the chemical reaction at the lead-off wire. This cartridge contains enough AgCl to last the lifetime of the electrode.


What are ISM lab pH sensors?

In sensors with ISM® functionality, important information stored on a chip in the sensor is automatically detected by the meter for easier measurements and recordkeeping. These include:

  • Sensor name and serial number
  • The last five calibrations
  • Initial factory calibration data
  • The maximum temperature the electrode has been exposed to


These sensors are only compatible with SevenExcellence™, SevenCompact™, Seven2Go Pro™ and SevenGo Duo™ meters.


Can the temperature be compensated for when measuring using a laboratory pH electrode?

Temperature has an influence on both the electrode and the sample. Following the Nernst equation, the measured pH andslope linearly depend on temperature. The sample measurement cannot be compensated to any reference temperature, because every sample has its own pH–temperature dependence. During the measurement only the slope is adjusted to the temperature of the measurement. The result is displayed only for the temperature of the measurement. Only pH calibration buffers’ behavior is fully predictable and can be compensated by using an electrode with an integrated temperature sensor.


Can laboratory pH probes from other manufacturers be used with METTLER TOLEDO pH meters?

Yes, our pH meters have a BNC socket that can support third party sensors with BNC connectors. However, some specialized features such as ISM may not work.


How should I inspect a new lab pH electrode for completeness and quality?

Check out the following video to learn inspection techniques.


Is it possible to measure the pH of pure water with METTLER TOLEDO's lab pH sensors?

The purity of water is an important aspect in many industries and sectors such as pharmaceutical, food and beverage, life science, power plants, and many others where pure water is required for day-to-day laboratory testing and other activities. The pH measurement of pure water samples can be difficult due to the low conductivity of the sample, fluctuations in electrode liquid junction potential, and glass membranes sensitivity. With our specialized pH sensors, it is possible to measure the pH of pure water samples. Watch this video to learn more or check out our sensor here.


Are there any specialized laboratory pH electrodes for the food and beverage segment?

Yes, METTLER TOLEDO offers an array of specialized sensors for measuring the pH of various foods and beverages. To learn more, click here.


How can a laboratory pH electrode be regenerated?

The pH-sensitive glass membrane can be reactivated using a regeneration solution. This solution contains ammonium bifluoride. All the necessary safety precautions must be taken while handling these acids, e.g. wear protective goggles, a laboratory coat and chemical-resistant gloves.

  1. Measure a minimum amount of the solution in a small acid-resistant vessel.
  2. Dip the tip of the pH sensor into the regeneration solution for 5 to 15 minutes.
  3. Ensure the maximum immersion point is at the level of the upper shoulder of the pH-sensitive glass.
  4. Never dip the pH sensor shaft into the solution because the hydrofluoric acid will damage it.
  5. Rinse the pH sensor thoroughly with water and condition it for approximately one hour in a buffer solution of pH 7.
  6. Finally, place the pH sensor overnight in the specific reference electrolyte.


Please refer to our troubleshooting video showing the step-by-step process of pH sensor regeneration.