pH 7, pH 9 calibrate solution can keep after first used?

[SixtyNine]

Hello

pH 7, pH 9 calibrate solution can keep after first used?
Can use another time?

[Matthias]

it depends on the accuracy you want

I use my solution for 2 years now

[Antipodes]

As do I, but I do my best not to contaminate buffer solutions by cleaning the probe in RO water after using it in one buffer and air blowing it to get most of the moisture of it before putting it in the next buffer.

[SixtyNine]

Thank bros.

[Gunther]

For calibration I use test tubes with a very small amount of calibration fluid and throw it away afterwards (the used fluid, not the test tube
With the tubes it takes no time to get the tank temperature and there is no contamination of my calibration fluid.