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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: duende on April 30, 2014, 11:00:23 AM

Title: Zn + EDTA
Post by: duende on April 30, 2014, 11:00:23 AM

Hi everybody,
I'm a student of Biology. I'd like to ask you something. I grew my microalgae in a culture medium containing - among other things - Na2EDTA 8.29 µM, Na2EDTA 6.56 µM and ZnSO4 254 nM. How can I calculate the [Zn]
bioavailable and not complexed with EDTA? Are there programs to do that?
Thanks guys!

duende

Title: Re: Zn + EDTA
Post by: Borek on April 30, 2014, 11:29:38 AM

You should calculate concentration of EDTA^4- from pH, then Zn²⁺ can be calculated from the stability constant (and known total concentrations of EDTA and Zn). Not a trivial task, but definitely doable.

Quote from: duende on April 30, 2014, 11:00:23 AM

Na2EDTA 8.29 µM, Na2EDTA 6.56 µM

So which one it is?

Title: Re: Zn + EDTA
Post by: Big-Daddy on May 09, 2014, 03:13:00 PM

As your Zn²⁺ is consumed, though, more of the complexed form will shift back to Zn²⁺. As far as I can see, if you want a reasonable quantitative treatment of this you need to know all the reactions - including some idea of how to model the biological processes you're about to make happen. Otherwise, once "all" your free Zn²⁺ is consumed, it'll simply be replaced.