I am trying to build a circuit that interfaces a standard pH electrode to a PIC (18F4550). I need the PIC to also use a DS18B20 for temp reading and use that data to correct the pH reading. I thought this should be OK with only software coding in the PIC since the temp data will already be digital. I have seen many schematics for the pH probe amplification but their temperature compensation seems to involve thermistors of some sort and is handled at the ADC end; or they're considering a probe with both the sample and a reference electrode lead (which I'm not using). My electrode has the single bnc connection.
Any suggestions on how to integrate the DS18B20 data into a correction routine?
Also, any experience recommendations on the ADC Amp would be SUPER helpful too. There are quite a few in the fA input biasing range, I can't decide. I'd prefer to avoid the guardrings if possible.
EDIT1: OK, thanks all for the advice. I have taken the lazy way out and bought the atlas scientific sensor interface board. It is a uart board that can do the calculations itself. I just have to figure out how to get the temp data sent to it by uart. I posted a separate question about that (atlas code was confusing). But this process should be much easier. Also, considering some other advice, I've switched to the 18f46k20.