[FernandoVI]

Dear colleagues

I am validating the method of copper determination by volumetry in mineral concentrates. I am using a solution of sodium thiosulfate to determine the copper content in samples.

My question is what material should I use to standardize the sodium thiosulfate solution. I am using Copper in sheets of Merck 1.027000 but this material gives me an analysis certificate with a purity of 101.2%.

Is it correct to use this purity to correct the Title of the sodium thiosulfate solution? Should I assume only 100%? Should I use a material of different quality? Any help will be good

[Arkcon]

There are other ways to standardize the sodium thiosulfate titrant.  You can purchase it standardized, or standardize it the way that you're doing.  It all depends on the method that you must follow, and what you claim will be your results.

There is no reason your standard purity can't be > than 100%.  And yes, you should use the quoted value, unless you have a better value -- from your own analysis -- not just, "Can't be better than 100%, so I'm using that."

[Arkcon]

http://www.chemicalforums.com/index.php?topic=23575.0