"Tre' Landrum" wrote in message
news:5LCid.13517$233.3377@okepread05...
OK, I really don't understand this statement "You can not check the pH of
RO/DI water, with a pH meter or a test kit." You are measuring the among
of
H+ ions in the water. How does the lack of other ions have a negative
effect
on the pH measuring? I am working on my post doc... so feel free to use
the
big words. Thanks.

Tre'


Doesn't metter. If the DI water really is DI, the PH should be exactly
7.00. Although that is almost impossible to attain. DI water starts
absorbing CO2 and the PH starts going down almost immediately unless you
shield the water. If your DI water has a high or low PH, it simply is no
longer DI water, plain and simple (with the exception of CO2 acidification
of course which is reversible).

And as for the PH meters, make sur you calibrate using two buffers. Using
one only moves the response up and down. If it reads 5 at a PH of 6 and 6
et a PH of 7, then adjusting the PH down by 1 unit will bring both PHs in
line. However if it reads 4 in a 6 buffer and 7 in an 8 buffer, then the
slope is also off. Using two buffers allows you to adjust both. Hard to
explain with drawing a picture.

Robert