Fiske and Subbarow reagent . . .

[Dr E. Buxbaum]

For the ANSA reagent dissolve 37.5 g Sodium metabisulfite, 0.625 g ANSA 
and 2.5 g Sodium sulfite in 250 ml Aq. bidest. by warming and filter 
while warm. Keep refrigerated in a brown bottle.

You also need a solution of 2.5% Ammonium molybdate in 2.5M sulfuric 
acid.

Mix 4.5 ml Sample (up to 10 micro M phosphate) and 0.3 ml Molybdate, then 
add 0.2 ml ANSA reagent and incubate 10' at RT. Read at 620 nm. 

The publication is in JBC 66 (1925) 375-400