[mercury]

Hi,
I would like to know why KMnO4 is needed to be decolorized using Hydroxylamine when doing digestion of samples for mercury( method reference:USEPA 7470/7471).The method only states it is done to remove the excess KMnO4. What is the purpose of removing this excess and what's wrong if we leave this excess KMnO4 as it is during sample preparation?Cold-Vapour technique is used for measurement of concentration.
Please help as it has been a real task getting information on this.Thanks in advance!

[kevins]

Hint: what kinds of chemicals (reagents) will you use in Cold-vapour technique to generate the mercury vapour?

[mercury]

Well the kind of chemical (reagent) used in Cold-vapour technique to generate the mercury vapour will be the SnCl2..What's the connection of this question to the question I asked?

[kevins]

If the solution contains oxidizing agent (KMnO4), the function of SnCl2 will... how to generate the Hg...