Buffer Solutions are required to calibrate the pH Meter/Electrode system.

In busy laboratories it is recommended that a calibration is performed at least once per day or preferably twice. A two point calibration is usually performed, either pH7 and pH4 buffer or pH7 and pH 10 depending on whether the sample is acidic or alkaline.

Buffer solutions should not be used as electrode storage solutions. Purpose made storage solutions are available for this purpose. 

The EDT direction Buffer Solution is pH4.00 at 25 degrees centigrade. Please check that you are calibrating correctly in accordance with your pH meters calibration set points.

A common error is to assume all buffers are the same. They are not! Buffer solution pH 7.00 at 20 degrees and pH7.00 at 25 degrees are 0.02pH different at the same temperature. The difference is greater in pH 4 and 10 buffers.