WSM - 2-3-2010 at 19:04
Hi All,
I acquired some N-phenylanthranilic acid to test for residual chlorate in a perchlorate cell. The Merck Index reference for N-phenylanthranilic acid
lists it's use as a reagent for Vanadium. Does anyone have a clue how this is done?
Please illuminate me if you know. Thanks. 
WSM
WSM - 2-3-2010 at 19:11
I forgot to mention. The reason I'd like to test for vanadium is to determine whether titanium from unknown sources is CP (commercially pure) or an
alloy. Many titanium alloys contain vanadium so a positive test for that metal tells me it's the wrong stuff for my application (cathodes for
electrochemical cells). Thanks for any help you can offer.
WSM
not_important - 4-3-2010 at 04:22
I don't know the details, phenylanthranilic acid is used as a redox indicator being colourkess in the reduced state, pink-purple in the oxidised
state, and pale green when re-reduced; it is used as an indicator when V(5) is used as an oxidising titrant. I suspect the use in steel analysis is
as a redox indicator at a stage where V(5) is being reduced in a titration with a reducing agent such as Fe(II) ammonium sulfate.
Quick tests that come to mind are a bead test, V giving a yellow bead in oxidising flame and green to blue-green in the reducing flame.
A wet test would be to take a solution of the sample in aqueous HCl and perform the standard H2S precipitation to remove interfering elements, then
oxidise the filtrate with hot HNO3 until all Cl is driven off. Then neutralise with 10% NaOH, followed by pouring the sample into a several-fold
excess of the same, boil for a few minutes, and filter. Treat with filtrate with a solution of lead and ammonium acetates to precipitate lead
vanadate.
The PDF at http://handle.dtic.mil/100.2/ADA075883 talks about the analysis of steels and Al alloys including testing for V.
[Edited on 4-3-2010 by not_important]