[Babcock_Hall]

I was recently asked about how to do this, although I don't know how accurate the pH values have to be.  I checked my copy of the Beckman Handbook of Applied Chemistry.  It has a section on colloidal samples, but it did not have a specific discussion of how to obtain the pH of milk.  One aspect that might be problematic is that there will be milk proteins.  I have heard of commercial reagents that are designed to clean electrodes onto which protein samples have been deposited.  The person who wishes to do this may not have a large budget; therefore, if I can supply him with (for example) urea or whatever reagent would be most appropriate, that might be the way to go.  Thoughts?

[Arkcon]

The colloidal dispersion of fats in homogenized milk shouldn't be a real problem for determining pH, the fats don't have to be in solution for them to have their pH effect.

Cleaning fats and proteins off of electrodes after use for biological samples can probably be done easily with detergent.  Or with enzymes, occasionally.  Making this sort of thing part of weekly maintenance might be a good idea.  Changing the filling solution at that time, and leaving the electrode to soak over the weekend.