Accurate measurement of pH - best methods

[fsonnichsen]

I am "proofing" various pH probes in an in-situ fresh water environment--this is a low electrolyte environment where such probes typically do not perform very well. I want to routinely sample the water and obtain accurate pH data for comparison. Can someone enlighten me on the what modern (non electrochemical) methods might be used for pH determination to around 0.01 accuracy? I have used bromocresol colorometric titration but my methods are probably quite dated. I expect there are now some standard accepted tests for comparison of pH results.

Thanks!
Fritz

 

[Bystander]

used bromocresol colorometric titration but my methods are probably quite dated.

Your methods are also what you are used to employing.

pH determination to around 0.01 accuracy?

That's some pretty "tall walking" there; 0.01 is how much in terms of free energy?

 

[BillTre]

I would talk with some pH probe manufacturers. They know a lot and have obscure products for unusual uses.
There are some new technologies out there, like probes that can optically determine pH, that may work for your application.

These are some issues to decide:
Do you want to leave the probe in the water continuously?
How often will you calibrate it?
Will it get fouled with debris from the water? --> cleaning methods
How rugged do you want it?