difference between folin-denis and folin-ciocalteu is lithium sulfate and bromine.
preparation method of folin-denis : mixing sodium tungstate , phosphomolybdic acid and phosphoric acid (2hr under refluxing ).
preparation method for folin-ciocalteu : mixing sodium tungstate , sodium molybdate , phosphoric acid and conc. hydrochloric acid (10 hr under refluxing ) then add lithium sulfate and bromine .
can I prepare folin-denis by mixing sodium tungstate , sodium molybdate , phosphoric acid and conc. hydrochloric acid (10 hr under refluxing ) or not ?
can I replace phosphomolybdic acid by sodium molybdate and conc. hydrochloric acid and increase reflux time to 10 hr ?
Dear Nuha
Yes you can replace it because molybdate will react with phosphoric acid and HCl in solution to give phosphomolybdic acid but you should call it "Folin-Denis like reagent" because you don't know of the quantity formed is equal to that used in the original reagent.
Regards!
NOBOSSE.
Also, Folin and Denis developed the FD reagent in 1912 but facing the problems of precipitation and instability of chromophore, Folin and Ciocalteu improved it in 1927 and made the FD reagent in which phosphomolybdic acid is replaced by sodium molybdate and HCl but the main change was addition of lithium sulfate and bromine to prevent the precipitation and instability of chromophore.
So, why are you trying to prepare the FD instead of the FC which is better ?
Regards!
NOBOSSE
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