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Determine the concentration of hypophosphorous acid in presence of tin

2006

I need to measure the concentration of hypophosphorous acid in the plating bath with the presence of Sn+2. Anybody know how to eliminate Tin out of the solution and measure the concentration of hypophosphorous acid?
The concentration of hypophosphorous acid is about 50-120g/L and the tin concentration is about 25-70g/L.
Thanks,

Gtong
student - Hong Kong

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I would filter the sample carefully, then do a titration with either standard iodine or iodate solution. This gives you the combined Sn2+ and hypophosphite concentration.

Then, I would determine the tin concentration via AA spectroscopy ⇦this on eBay or Amazon [affil links] , and get the hypo result by difference. If I did not have an AA, I would assay the tin by a gravimetric method using cupferron as precipitant, followed by ignition of the precipitate, and weighing the resultant SnO2.

Dave Wichern
Consultant - The Bronx, New York
2006

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Gtong -

Maybe this is a dumb idea, but could you get an idea of the hypophosphorous acid simply by doing an acid-base titration? Then you wouldn't need to eliminate the Sn+2 interference. I don't have any experience with this acid, but I see that is is classified as a powerful reducing agent.

Terry Tomt
- Auburn, Washington
2006