Has anyone been able to make the current PF dissolution work for the 5 mg strength? If so, what system are you using. There does not seem to be enough signal on a Waters system. For the rest of the readers, this method is an indirect detection method with very dilute nitric acid providing the baseline absorbance.

I haven't used to method personally, but I have corresponded with others who have. I know that it's a bit finicky but I believe it can be made to work. The indirect detection method is fundamentally not very sensitive so you have to be willing to put up with a fairly poor signal to noise ratio. There are other methods for detecting chelating agents which are more sensitive such as post-column addition of iron (e-mail me directly if your interested in the specifics) with detection at 330 nm. Another problem that needs to be dealt with is metal contamination. Since the analyte is a fairly good chelator you'll often see aberrant peak shape associated with formation of and/or dissociation of complexes formed as a consequence of metal contamination of the separation column. Its generally a good idea to make a few injections of massive doses of EDTA in order to strip any metals off the column (i.e. at least 1000 ppm EDTA).

Thank you for your response. We are looking at another detection method already. I or somebody needs to respond to USP to prevent this monograph from becoming final. It is clear that, as written, the USP method does not allow for this method to work. I was hoping that there was some instrument specific issue related to dead volume or detector optics. I have a general question for all readers of this forum. Do individuals who submit monographs purposely leave out important details so that competitors can't get the method to run? The USP requires you to recommend a specific brand of column. If a column has to be preconditioned that would be an important detail.

Yes, details are left out of the monographs. The USP also allows there "experts" to modify monographs based on their "expert" opinion, but I do not believe that the "experts" actually test their changes.