[qwerty222222]

Hello,

Not sure if this is the right place to post this as I am new to the forums....

I am running an experiment involving zinc dissolution, and need an appropriate pH buffer to keep it at 7.4 at 37 deg C. Due to the post experiment analysis it is important that there is no zinc precipitation at all - I have made the error of using a phosphate based buffer and watched my ionic zinc concentration go to zero...

Also, the simpler the buffer, the better - but compatibility is the most important thing.

If anyone can help, then thanks in advance!

[Borek]

TRIS, BIS TRIS, TES, BES, HEPES, DIPSO, TAPSO, ACES, PIPES - I am not saying any of them will be compatible with zinc, but it should give you a new direction to think about.

[cheese (MSW)]

Calculate the [Zn^2+] at pH 7.4 given that Ksp[Zn(OH)2]  = 3 × 10^-17.[1] 
This is the max conc of Zn^2+ at physiological pHs and is independent of the identity of the buffer.
[1] http://www.ktf-split.hr/periodni/en/abc/kpt.html
This is at 25 °C; it will be slightly better at 37°C.

[Borek]

Calculate the [Zn^2+] at pH 7.4 given that Ksp[Zn(OH)2]  = 3 × 10^-17.[1] 
This is the max conc of Zn^2+ at physiological pHs and is independent of the identity of the buffer.

This is not exactly true - depending on the ions in the solution zinc will be present not only as Zn²⁺, but also in numerous complexed forms.

[cheese (MSW)]

Virtually all Zn(II) cmplxs (eg. [Znen3]^2+) are labile and at pH ~7 will hydrolyze to [Zn(H2O)6]^2+.
Zn cmplxs (and I am guessing) that maintain their integrity would be cmplxs such as Zn-porphyrin,
but then the Zn^2+ will not be available for delivery elsewhere.
http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=2735172#pharmaction