APEX pH Probe Calibration Differences

[Meitzler]

What is the closest anyone got to calibrating 2 pH probes connected to the same APEX. I can not get better than .12 and usually the difference is .2. I am using Neptume pH probes, one lab grade and one standard grade.

 

[phuzzykins]

The standard grade pH probes are accurate to within .1 pH; I'd consider a .12 difference between two probes to be fine. If one is .1 pH low and the other is .1 pH high, then you'll see a difference of .2 pH. That's at the extreme end of allowable.

If you're looking for the two probes to match exactly... give up now. You can recalibrate the same probe from the same reference solutions all day long, and there will still be small differences in the calibration.