[Babcock_Hall]

We do a good deal of protein modification in my lab, but we rarely work with iodoacetamide.  Can a stock solution in water be made, or is the rate of hydrolysis too fast?  I think that the amount we need is too small to be weighed out and added directly to the reaction.  We will be modifying a catalytic cysteine residue.
EDT
So far, everything I found suggests preparing an aqueous solution fresh at high concentration, such as 0.5 M (and presumably not trying to store it).  Besides hydrolysis, light is also a problem.

[Babcock_Hall]

Some manufacturers sell this compound in small, pre-weighed aliquots.  This also suggests that single use is the way to go in cdertain applications.