Anatech Ltd. has a product (Cat. #201, Reform Assay Kit) designed to 
test the formaldehyde content of NBF or any of the aqueous zinc 
formalins.  It is a simple titration method with a very conspicuous 
end point.  It readily detects differences as small as 0.5% formalin 
over a range of 3-20% formalin.

Dick

-- 
Richard W. Dapson, Ph.D.
Anatech Ltd.
Battle Creek, MI
800-ANATECH (800-262-8324)
email@anatechltdusa.com
Web address:  anatechltdusa.com