[JNU]

Hi,
http://www.pharmacopeia.cn/v29240/usp29nf24s0_m83730.html
This link is for assay determination of titanium dioxide by titration . I don't understand why is ammonium hydroide added at the end of the sample preparation
Thanks.

[Hunter2]

Instead to post the whole thing, copy the part you dont understand, I couldnt find the part with the ammonium hydroxide.

[Arkcon]

If you have a need to understand a pharmacopoeia assay, and you belong to an institution that subscribes to the current pharmacopoeia, you can easily email them, and ask any question you want.  They're glad to help, and will provide peer-reviewed references.

If you have a job to do, you just follow these methods as written, because otherwise you're in violation of the current production standards, unless you validate an alternative method.

More than once, I've called the USP the "drunken frat boy's guide to chemistry" -- the methods seem to use the most obscure, archaic, chemicals and methods possible.  I'm speaking mostly about the wet chemical methods for heavy metals, gradually being replaced by instrumental methods.

Only a real chemistry expert truly understand some of the most obscure assays.  Why do you need to know why ammonia is added?

[k.khan]

Hi,
I am interested to get the CHEMICAL REACTIONS, take place for the Assay of Titanium Dioxide by Titration Method.

Thanks

Frank

[Arkcon]

Sorry k.khan:, but the answer to your question is likely the same as the answer to this original question you revived to ask yours:

1). Ask the USP
2). Its too hard for the average chemist to know
3).  You don't need it anyway

You can always try to figure it out.  What's the last step?  How is it done?  What does the titration do?