So far we have tried a variamine blue assay from Narayana et al. 2006 and a silver nitrate precipitation from Simeonova et al. 2004.

In the variamine blue assay instead of intensity correlating with concentration intensity is anti-correlated; the dye actually turns orange in the presence of arsenite.

In the silver nitrate precipitation we do not get the same colors or dyanmic range as the paper. There is also a lot of precipitate from the tris-chloride buffer alone.

Does anyone have insights or other quantification methods to suggest?