pH problem

jnsmar14 at jnsmar14 at
Sun Oct 4 09:58:26 EST 1992

I am having problems adjusting the pH of various 1 M solutions (citrate,
succinate etc.). My pH electrode, if left in these for a while (few minutes)
seems to drift, in the sense that when I rinse it with distilled water, and put
it back into my reference buffer, I get a lower pH value than I know it should
be. This obviously doesn't bode well for accurate pH's in the above mentioned  
solutions! What exactly is the influence of ionic strength on pH? I also don't
always get corresponding pH values with pH-paper. Can anyone tell me what is
happening to the electrode? 

Pierre Janssens
Zoology Dept.
University of Cape Town

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