On Fri, 20 Jul 2001, Keith  Ryan wrote:

> Can anyone comment on rubeanic acid and pyroantimonate methods for copper?

Rubeanic acid (usually sold under its more sensible
name of dithiooxamide) stains copper deposits in
an unpleasing shade of dark green. It is a specific
but not the most sensitive histochemical method for
Cu.

Potassium pyroantimonate gives insoluble precipitates
with various metals, notably sodium and calcium. (I
hadn't heard of it doing this with copper, but maybe
that too.) The insoluble pyroantimonates are electron
dense but not visible. The method has low specificity
and was most often used for calcium.

For more information, see Pearse's Histochemistry
4th edn Vol 2 Chapter 20 (1985).

----------------------------------------
John A. Kiernan
Department of Anatomy & Cell Biology
The University of Western Ontario
London,  Canada   N6A 5C1
   kiernan@u