Ah thanks Hypo.
Wuz wondering..
tincture is expensive & comes in a fixed concentration of 2.5 % KI, 2.5% I2 (in my case),
KI is required to dissolve the I2,
would it be feasible to add to the Na vanillate soln your tincture,
then as the dissolved I2 reacts (the 2.5% originally present),
solid I2 is added to the mixture (recovered from tincture naturally) at the same rate that it is used up so that there is always enough KI to dissolve all of it (i.e. maintain less than or equal to about 2.5% I2) until all the required I2 is added...
Hmmm..hope I has made a sensible question...wine is fucking with me receptors and my reception so its hard to tell