pH Meter Buffers
When calibrating an electrode, most pH meters request that you input the type of buffers which will be used. There are several manufacturers of buffer solutions and the specifications of the most commonly used brands normally already come programmed as tables in the pH meters.These tables cover groups of buffers for a range of temperatures. In this way a whole group can be chosen at once allowing the temperature dependence of the individual buffers used for calibration, to be taken into account.
If no internal or external temperature sensor is used, ensure that you calibrate and measure at the same temperature. In this case remember to manually input the temperature to allow the meter to perform the buffer temperature correction
The buffers which are used for the calibration are very accurate solutions with a guaranteed value and precision. To keep the buffer solutions suitable for calibrations for as long as possible after opening it is advisable that you follow these guidelines:
- Mark the date of first use on the bottle of the buffer solution.
- Keep the buffer solution bottles tightly sealed at all times and use the decanted buffer immediately.
- Never return used buffer back into the original bottle or mix calibration standards from different manufacturers.
- Ensure that no contaminants enter the buffer solution bottle and always keep the bottle sealed.
- Store the calibration standard at ambient temperature.
- Do not store the bottles of buffer solution in direct sunlight.
- Clean the electrodes before calibration and do not calibrate directly in the original buffer solution bottle.
- Never use a calibration standard with an expired use by date or that you suspect is contaminated.
- Replace the buffer solution with a new bottle after it has reached its expiry date.
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Source of article: A Guide to pH measurement by Mettler Toledo
