pH Buffer

For calibration of pH combination electrodes

Selection of the buffers

For two-point calibration, the two buffer solutions are selected in such a way that the pH to be measured is between the values of the two buffers where possible.
The ability to calibrate pH 4 and pH 9 to cover the whole pH range is only seemingly advantageous. Due to non-linearities of the meter and of the measuring amplifier, however, it leads to significant errors.

Handling buffer solutions

To ensure exact calibration, buffer solutions must be handled carefully. All dirt is to be avoided.
Therefore, never pour buffer solutions back into the storage bottle or calibrate directly in the storage bottle. Used buffer solutions are disposed of and not used a second time.

In the case of alkaline buffer solutions (pH > 7), the CO₂ in the air causes a gradual neutralisation of the buffer. The storage bottles should therefore be resealed as soon as possible after use and contact with air reduced to a minimum.