I mentioned in another thread that I use a Hanna HI-98128 pH meter, but always use the Taylor K-2006 kit to double check it. I know I'm doing it twice, but I have a reason. One, is I like the second decimal place readout of the Hanna. It doesn't make any difference except I can kind of watch trends a little closer. Second and most important to me is I simply can't see the difference between 7.6 and 8.0 on the Taylor comparator. I've tried every kind of light and every kind of background.

So my question...is there a way, using the R-0005 acid demand reagent, to calculate the actualinitialpH reading by starting out with the sample and adding the acid demand reagent until the sample is 7.4 or 7.2 on the comparator? I have no problem discerning those colors.

For example, if I start out with a sample and it's 7.6 or above. If I put one drop of R-0005 in and it falls into the 7.4 range, can I surmise what the actual initial reading was? Another way to put it is, if I do the above, can I calculate, by number of drops of R-0005 used to get to 7.4 on my comparator, the starting pH?

Thanks very much,

Howard