NaI ... is it a chaotrope?

Frank O. Fackelmayer Frank.Fackelmayer at
Sat Oct 23 04:06:52 EST 1999

Bill_A_Nussbaumer at wrote:

> Bill A Nussbaumer at BDX
> 10/22/99 11:45 AM
> I was reading about the procedure to bind DNA to glass beads using Sodium
> Iodide.  Is NaI considered to be a chaotropic salt?
> Thanks,
> Bill

Hi Bill,
There is a general rule to estimate the effect of a salt on protein
precipitation ("salting out") and solubilization ("salting in", also
referred to as chaotropic effect). The rule is called the "Hofmeister
series" after the guy who first described it, and goes

                                       <- increasing precipitation
("salting-out") effect
anions:  PO4(3-) > SO4(2-) > CH3COO(-) > Cl(-) > Br(-) > NO3(-) > ClO4(-) >
I(-) > SCN(-)
cations:  NH4(+) > Rb(+) > K(+) > Na(+) > Cs(+) > Li(+) > Mg(2+) > Ca(2+) >
                                        increasing chaotropic ("salting-in")
effect ->

So for NaI, it is clearly chaotropic.

Hope this helps,

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