Sorry, this would not work then. I did not realize that you wanted to
have vanadate around. Cysteine is a pretty good reducing agent, it
would get eaten by it.





wrote in message ups.com...
Muhammar wrote:
I would recommend trying L-cysteine hydrochloride hydrate (or
L-cysteine; it is the same thing). It is reasonably cheap and
nontoxic
- edible. The only disadvantage is that while the stuff is stable as
a
solid, the aqueous solutions have to be stored in fridge to slow down
the air oxidation. Oxidized cysteine solution can develop
precipitate.
If you add some antioxidant (ascorbic acid!), the solution will keep
longer.
This sounds good. Storage is no problem, because the solutions are not
stored. They are prepared, just before use and then they are discarded.
I only wonder if L-cysteine withstands the oxidizing power of copper
(II) or [VO2](+). The latter is a fairly strong oxidizer with a redox
potential (for V(+5) to V(+4) at pH=0) equal to 1.0 V. Using ascorbic
acid as antioxidant does not work, this reduces copper (II) to
copper(I) at once and the pervanadyl is reduced to blue vanadyl
immediately.


[Also, try to sell your cysteine/ascorbic photo solution to a
nutrition supplement stores as well - the body builders will quaff it
down by a pint]
I also have a bottle containing some nice blue VOSO4.xH2O, the ideal
stuff for bodybuilders... I, however, prefer to keep my health :-)