Bill

An electron mircroscopy way, if it isn't coverslipped, would be to
simply put it into an SEM equipped for x-ray microanalysis.  No
further preparation in case you needed to process it further yourself.
 It would be exposed to vacuum and the electron beam which might cause
some "burning" or mass loss.  It would take me about 5 minutes to give
you an answer of whether it was there at more than about 0.1% in any
local (dry) mass that you focus the beam on, and it focuses down to
less than a micron diameter.  Maybe that isn't sensitive enough.
Given longer, I could ash the slide in an oxygen plasma, this is good
for tissue granules because the organic tissue is removed.  Not good
if your mercury is linked to organics! Like metallothionins
(spelling?).  But I'm in England!

Good luck - Keith


_______________________
Keith Ryan (Dr)
Marine Biological Association
Citadel Hill
Plymouth
Devon PL1 2PB
England

Tel. 0044 (0)1752 633279 (with answer machine)
also 0044 (0)1752 633249
Fax. 0044 (0)1752 633102

e-mail: kpr@wpo.nerc.ac.uk