Fri Oct 09, 2015 3:01 pm by mleipold
To the best of my knowledge, Fluidigm MAXPAR salts are supplied at 50mM.
One thing to keep in mind when you're making maleimide-DOTA (or any other small molecule chelate, such as the SCN-Bz-EDTA used with Pd in Zunder et al and Mei et al): in most cases, you're not purifying it afterward. In other words, you make a stock solution of the mDOTA or SCN-Bz-EDTA, then add in whichever metal salt, and then either lyophilize or use without any subsequent HPLC purification or anything.
As such, unlike loading the MAXPAR polymer for antibody conjugation, you don't have washing steps to get rid of excess metal ions. Therefore, you typically want to use a slight excess of the chelator *over* the metal ion concentration: this way, at least in theory, *all* of the metal gets taken up and therefore there is no free metal to streak or leach in your samples.
This is often a 2:1 chelator:metal molar ratio (0.5x metal), but you could probably go up to 1:0.8 chelator:metal ratio (0.8x metal) without an issue. I don't think I'd go further, just to be absolutely sure I avoided pipetting/dissolving errors, but that's up to you.
Mike