Laboratory pH Sensor

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.

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.

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.

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.

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.

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.

Check out the following video to learn inspection techniques.

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.

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

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.