> From: ac554 at freenet_carleton.ca (David Whittaker) > > Just a wild guess, but maybe the DUPLA product contains a sodium salt > of EDTA instead of Fe:EDTA, Mn:EDTA etc., i.e. metals already chelated. > I think that Allgayer and Teton mention this method in their book. > Another reason not to use DUPLA? Umm, what's the other reason? George