pH Lab Customer Support

Expert Support for Your Applications

We're here to support you with your METTLER TOLEDO products for pH, conductivity, redox potential, ion concentration, and dissolved oxygen measurements. Dive into this page to explore answers to common questions and discover valuable resources tailored just for you. Still can’t find what you’re looking for? Don’t hesitate to reach out via phone or email—our dedicated team is eager and ready to assist you!

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Troubleshooting

My pH Calibration Is Failing

Check if you have the right buffer group set up on your instrument

Modern pH meters use an internally programmed buffer table to calculate the calibration curve. If the buffer you use does not correspond to the buffer table chosen in the meter, the calibration will be wrong. Not sure how to check what buffer tables are set up in your instrument? Find the manual at:

Technical Documentation

Check if your buffers are fresh

pH buffers have an expiration date; if your pH buffer is expired, it will no longer be reliable.
Even within the expiration date, pH buffers can be affected if they have been opened for a long time or if they have been contaminated.
In case of any doubts, replace the buffer with a fresh bottle.

Check the condition of your pH sensor

Is the glass membrane intact?
Is the electrolyte level sufficient (in case of a refillable sensor)?
Are there any air bubbles or crystals inside the sensor, and is the buffer clean and clear?

If the issue persists, get in touch

If the issue persists, get in touch: ph.lab.support@mt.com

My Conductivity Calibration Is Failing

Is it a sensor with a certified cell constant?

Conductivity sensors InLab 741 and 742 (recognizable by their stainless steel shaft) are calibrated to high precision in the factory and do not need to be calibrated again—a verification is sufficient. If you have such a sensor, ensure that the cell constant in use corresponds to the one printed on the quality certificate.

Check the conductivity standard

Is the conductivity standard you use the same as the one that is set up on the instrument?
Is the conductivity standard still within its specified expiry date? How long has it been opened? Low-conductivity standards should only be used immediately after opening.

Are there any air bubbles?

Air bubbles will significantly affect the results of conductivity measurement. Tap the sensor, hold it at an angle, or remove it from the sample and re-immerse it repeatedly to remove the bubbles.

If the issue persists, get in touch

If the issue persists, get in touch: ph.lab.support@mt.com

My pH Readings Are Not Within the Expected Range

Was the pH sensor calibrated recently?

We recommend calibrating the sensor oneach working day to ensure the best performance.
If the sensor calibration is not producing satisfactory results, please check under “My pH calibration is failing”.

Does your pH calibration cover the measurement range?

For accurate results, it is essential that the calibration points “bracket” the sample pH value—that means there is at least one calibration point that is lower than the sample pH and one that is higher than the sample pH. We recommend that calibration points should not differ by more than 3 in pH.

If the issue persists, get in touch

If the issue persists, get in touch: ph.lab.support@mt.com

I Want to Download a Certificate of Analysis or Safety Data Sheet

The certificates of analysis and safety data sheets for most of our buffers and solutions can be downloaded at:

www.mt.com/buffers

I Have Lost My Instrument Password

If the issue persists, get in touch: ph.lab.support@mt.com

Documents

Please reach out to us with the serial number and article number to obtain your test report(s).

Please reach out to us with the serial number and article number to obtain your sensor certificate(s).

Library

Discover expert recommendations, handy tips, and smart tricks to help you get the most out of your products, ensuring precise and reliable results every time. This section offers detailed insights into specialized application areas to enhance your knowledge and boost your performance.