A pH meter is an electronic device used to measure the acidity or alkalinity of substances. As with all electronic weighing and measuring devices, it is important to calibrate a pH meter regularly to ensure its accuracy. If you fail to calibrate your pH meters, your readings may be skewed.
How often should you calibrate a pH meter?
pH meters lose some of their accuracy with every use. How often you calibrate a pH meter really depends on how accurate you need your measurements to be, how often do you use the pH meter, and what is the amount of possible contamination.
The more accurate you need the measurement to be, the higher the usage, and the higher the amount of contamination, the more regularly you need to calibrate the pH meter.
Generally speaking, calibrating a pH meter at least once or twice a month is recommended to avoid measuring errors.
You should also calibrate a pH meter if:
- You are using a new electrode
- The electrode hasn’t been used for a long time
- The electrode has just been cleaned
- You have measured a strong solution
- It is crucial to get a very accurate measurement
How to calibrate a pH meter
A pH meter can be calibrated with the following steps:
(Please note: If you are working with laboratory equipment and/or chemicals, ensure that you have the right safety equipment such as safety glasses and gloves.)
Step 1: Check and clean the pH electrode
Examine the pH electrode to see if there is any damage or contamination. Any damaged electrodes should be fixed or discarded. Once damage has been ruled out, clean the electrode with an appropriate cleaning solution suited for the contamination.
Step 2: Flush the pH sensor
Even if there is no need to clean the sensor, it is recommended to flush it with distilled water. This is to rinse off anything that may contaminate the buffer solution that you will be using next. Once the sensor has been flushed, gently wipe it dry with paper towels or lint-free tissue.
Step 3: Submerge the pH electrode
Immerse the electrode in a beaker filled with your first buffer solution. Use buffer solutions with known pH to make it easier for you to adjust the meter.
Step 4: Calibrate the pH meter
To calibrate or adjust the pH meter, keep an eye on the reading of the value. Once the measurement stabilises and displays the right pH value, set the device to accept this point.
Step 5: Rinse the pH sensor before repeating Step 2
Remove the sensor and rinse it well with distilled water. Wipe it dry, before immersing it into another clean beaker with the second buffer solution.
Calibrating your pH meter allows you to determine how far the meter deviates from the standard value. When done right and regularly, calibration will not only improve your measurement accuracy but also prolong the life of the pH sensor.
If you are looking for a new pH meter for your application, the Ohaus Starter 2100 pH Bench is a cost-effective smart bench meter suitable for a variety of laboratory applications.
To find out more about the pH meters we offer, please contact Anyscales directly.