2 replies to this topic

[prk]

We recently bought pH 4.0 and pH 7.0 buffer. I arrived as a clear liquid. Anyone know how we can color the solutions red and yellow?

[klinmed]

prk, on Jan 29 2010, 08:08 PM, said:

We recently bought pH 4.0 and pH 7.0 buffer. I arrived as a clear liquid. Anyone know how we can color the solutions red and yellow?

I have a feeling that you don´t really really know what it means to determine the pH of a solution with a pH meter . A "pH meter" cannot measure a "[H+) concentration" without a reference to a standard (calibrator). For example, a material that provided by the National Institute of Standards and Technology in the USA (NIST) or the P h y s i k a l i s c h T e c h n i s c he, Bundesanstalt, Germany (PTB) in  Europe.
If you change a calibrator preparation by for example by "altering it´s colour" you lose "traceability":  In effect your pH measurement has no real meaning.  If you want a colored standard solution you should buy one with colour. If you buy one without colour READ THE LABLE.

[newbie99]

prk, on Jan 29 2010, 04:08 PM, said:

We recently bought pH 4.0 and pH 7.0 buffer. I arrived as a clear liquid. Anyone know how we can color the solutions red and yellow?

why color them? if you want to distinguish one from the other, you can put red and yellow tapes on each container accordingly.

if you really want to color-code them, you can use FD & C Red No. 40 and FD & C Yellow No. 5. you'd probably need to re-adjust the pH because of the new addition. for this reason, i don't recommend you doing this.

either label them properly or go buy a color-coded version.