pH is used by chemists, biologists, environmentalists, and lab workers to determine how acidic or basic a solution is. A pH meter is the most helpful and precise instrument for testing pH levels. There are several easy procedures to guarantee you have the most accurate measurement of pH levels possible, from prepping your materials to meticulously calibrating and testing.
To give reliable results, any type of electrochemical sensor must be calibrated. Although the procedure of calibrating pH sensors is simple, many users are unaware of the factors and logic for this necessity.
To calibrate a pH metre, what do you use?
Two types of buffer solutions are required to calibrate a pH metre: pH7 and pH4. You utilise buffer solutions with a known pH so that the metre may be adjusted. Begin with pH7 buffer solution and then go on to pH4 buffer solution. However, for each pH metre calibration, be sure you use a new buffer solution.
What are the popular ways to calibrate a pH meter?
A pH metre can be calibrated in the following ways:
Method 1 (Two-point calibration)
- Dip the electrode into the pH7 solution first. The measurement will be steady after around 1 minute. The metre should read 7.0 on the pH scale. If this isn’t the case, set the pH metre to this reading.
- Rinse the electrode well with deionized water before immersing it in the pH4 buffer solution.
- Repeat these procedures until you get a solid measurement.
The two-point calibration is the most frequent pH metre calibration and is best used when you have a variety of pH samples. The buffer solutions should be placed between your predicted pH sample and the buffer solutions.
The pH metre estimates the slope and offsets error for the actual pH electrode in use throughout this operation. As a result of this information, the pH meter’s mV/pH equation may be adjusted to fit the electrode’s properties.
Method 2 (Multi-point calibration)
A multi-point calibration spanning a greater range of the pH scale will offer you the most accurate and reliable readings if you are grouping a wider range of the pH scale. This is when the pH metre is calibrated at three or more places, giving it a more accurate mV/pH equation throughout the range you want to cover.
- In a rinse solution, vigorously stir the electrode.
- Remove any remaining drops of the solution by shaking the electrode with a snap action.
- Allow the reading to stabilize after vigorously stirring the electrode in the buffer or liquid.
- Take a reading and write down the solution standard’s known pH value.
- Repeat as needed for as many points as you want. Based on the data points provided, the device will automatically establish the right calibration curve.
Why do you need to calibrate a pH meter?
The process of calibrating your pH metre by measuring liquids with a known pH value is known as pH calibration. This is necessary because the qualities of your electrode may vary over time, and you must account for this. A calibration does this by matching the present properties of your pH sensor to your pH metre.