PH probe seems high

[shardyl]

Hi

I just calibrated my ph probe but it seems to be reading too high at 8.59

I have checked with 2 other test kits and it would seem my ph is 8.2

my adc values are adc1 475 adc2 275

Is the proble faulty or could the calibration fluid have gone inaccurate over time?

thanks

[Antipodes]

Do you reuse the same fluid every time. Then yes it will be contaminated.

I purchased a litre bottle of each from a local supplier for test equipment.

So I have no concerns in in using new fluid each time.

I also wash my probe in RO water just after each measurement and blow dry with very light air, so that I do not contaminate the next buffer I put it into.

I also then place it back in the 7 buffer after the test to make sure it does read what it was calibrated to.

I would get some new buffer solution and then recalibrate and see if it reads correctly then.

If it is not correct, then try a new probe.

[shardyl]

Do you reuse the same fluid every time. Then yes it will be contaminated.

I purchased a litre bottle of each from a local supplier for test equipment.

So I have no concerns in in using new fluid each time.

I also wash my probe in RO water just after each measurement and blow dry with very light air, so that I do not contaminate the next buffer I put it into.

I also then place it back in the 7 buffer after the test to make sure it does read what it was calibrated to.

I would get some new buffer solution and then recalibrate and see if it reads correctly then.

If it is not correct, then try a new probe.

Thanks very much for that sound advice!

I will do do just that.