Analysis of cadmium and ammonium nitrate in stripping solution

A. For ammonium nitrate there are no direct manual titrations as others have said, but it can be determined with high accuracy and precision by thermometric titrations on an auto-titrator equipped with a thermometric probe. A NADCAP lab that I used to operate did hundreds of these over time with 5.0 mL of filtered undiluted sample and a 2N NaOH titrant ⇦this on Amazon [affil links] . You will need to determine the factor experimentally with prepared standards, but once that is done it is very fast and easy.

Other methods that we attempted to validate such as ISE, IC and indirect titration, were far less precise. The downside is that the thermometric equipment needed is not usually present in metal finishing labs and may not be worth the investment unless you already have the auto-titrator that is capable of accepting a thermometric probe.

A. Re. analysis of ammonium nitrate solution
This can be done by a modification of the method of analysing nitric acid in phosphoric chemical polishing solutions using Molar ferrous sulfate ⇦this on eBay or Amazon [affil links] solution as the titrant
Take a suitable aliquot, add 40 ml Phosphoric acid and 20 ml sulfuric acid and titrate to permanent dark brown colour.
Standardize against a known ammonium nitrate standard solution.

A. 20 gr/lt ammonium nitrate in solution is better.

A. Analyzing a cad strip tank is a bit of a waste of time. When it slows down, a 10% of a new make up and when it becomes too slow to be practical, dump it and make up a new one. What you see on the floor is a good an indication of the value of the tank as doing a test on it. Additional adds, after the first one, are a waste of money.
Take a look at the Keq for the reaction and you will see why.

A. I would recommend ICP analysis. You could also use the ICP ⇦this on eBay affil links] for many other things.

Can you recommend the best method for doing the ammonium nitrate in same bath?

thanks

A. I would agree with James that if you are doing this analysis for performance then it is a bit of a waste of time. Strip rate is the usual rate determining step. If it is excessive then you dump the solution and make a fresh solution.

If you are checking for other reasons such as environmental for disposal then if you have an atomic absorption spectrophotometer ⇦this on eBay or Amazon [affil links] this could do the job for you. What indicator are you using for the EDTA titration? If you are using eriochrome black t ⇦this on eBay or Amazon [affil links] or Solochrome T then you must be careful that you do not add too much indicator otherwise it blurs the endpoint.