Ph determination

I need to verify ph of a chromic acid solution in the .4 to .7 range. So far I have not been able to find a good stable way to verify ph at that level. Could anyone help with a suggestion.

Thanks,

Have you discussed this requirement with any company that makes pH meters?

Sounds like you are checking a chromic anodize tank. You need to use a good quality pH meter which will do either a 3 or 4 point calibration. Use 1.0, 4.0 and 7.0 buffers for the calibration. The more data points used in the calibration, the more accurate the result.

I agree with Phil and this is what we are doing in our labs. But still there is a question of how we are sure about measurements of pH below 1 ( I don't know of any buffer with pH 0.0 or even 0.5).We have to measure pH values, which have to be between 0 and 0.6! Do you have any suggestions?