A new highly sensitive staining agent for chromium (Cr) has been introduced
. This staining agent, 2-(8-quinolylazo)-4,5-di-p-tolylimidazole (QTI), was
found to be more than ten times as sensitive for Cr than the conventional
staining agent, Chromazurol S, and QTI also stained cadmium, copper, lead a
nd zinc. Differentiation between the staining of Cr and other metals was ac
hieved by immersing the tissue sections in dilute alkylamine solutions befo
re they were stained with QTI. Thus, it was possible to selectively stain f
or Cr by blocking other metals.