Are you trying to do this in vivo or in vitro?

If you are trying to do this in vivo, fluorescent dyes or GFP based metal sensor proteins are the only option I know without very specialized equipment. However, the dyes are expensive and the proteins may not be easy to get.

Dear Jeffery and Sami,

Thanks to both of you. I want to do this in vitro...

ICP-MS is the end point for me because of the Cost!

I need a more common approach...

If in vitro, use competitive binding to zincon, which is fairly cheap (1g US$28)

http://www.ncbi.nlm.nih.gov/pubmed/3122631