How to measure pH

pH is an important measurement across a wide range of industries, including food processing, laboratory testing and water quality testing. This guide provides instructions on how to measure pH with a benchtop or handheld meter.

What is pH?

pH or ‘potential of hydrogen’ is a measurement of the hydrogen ion activity within a substance. By measuring pH, you can determine acidic or basic a substance is, on a scale from 0-14. A pH of 7 is neutral, while a pH greater than 7 is basic, and below 7 is acidic. 

pH provides important information about the measured substance. For example, the pH of food products should be within a specified range to prevent microbial growth. pH is also measured in water quality testing to determine if water is safe for bathing in the case of sanitised pool water or suitable for environmental release in water treatment.

How to measure pH with a portable meter

Handheld testers and portable meters are often used to measure pH directly from the source without removing a sample.

1. Check the pH electrode is clean and hydrated for use
2. Turn on the meter
3. Place the pH electrode into the substance to be sampled or on the surface for solid materials and wait for stabilisation
4. Record the measurement
5. Clean the electrode and repeat the process for each sample

How to measure pH with a benchtop meter

Benchtop meters such as the HI-6221 Advanced pH Meter allow samples to be measured for pH in a laboratory setting, an ideal solution for larger batches of samples where high accuracy in testing is required.

1. Place the sample in a clean, dry beaker
2. Check the pH electrode is clean and hydrated
3. Turn on the meter and select the pH parameter, or connect the pH probe jack for automatic recognition in models such as the Edge
4. Lower the pH electrode into the sample and wait for stabilisation
5. Record the measurement
6. Clean the electrode and repeat the process for each sample

Best practices for pH electrodes

Proper maintenance processes are important for accurate testing results. These best practices help to keep your pH electrodes in good condition for measurement:

• Follow the correct cleaning process, using deionised water and blotting instead of wiping your electrode
• Store your electrode in storage solution to maintain hydration
• Clean your electrode between samples and between buffers when calibrating
• Calibrate with suitable pH buffer solution for accuracy as often as necessary for your specific requirements
• Ensure your electrode is properly submerged within the sample when testing, including the bulb and reference junction
• Top up the electrolyte level on refillable electrodes and check levels regularly
• Visually inspect your electrode before use for any damage including scratches and cracks

For more information on how to calibrate pH electrodes, see our complete guide here.

Buy pH testing instrumentation from Hanna Instruments UK

Hanna Instruments are world leaders in pH testing instrumentation. Our range includes handheld testers, portable meters, multiparameter photometers and advanced benchtop testing solutions. Browse our pH testing instrumentation online here.

For more information about measuring pH, contact our experts directly via email, or at 01525 850855.