Hi everyone,

I'm trying to detect MDA by derivatizing it with 2,4-DNPH. My question is, when I use MDA standard to react with DNPH, the reaction forms MDA-DNPH, which precipitates out of the solvent (75% ACN, 0.2% TFA). I have seen papers detecting MDA by DNPH but I didn't see anyone mentioning the precipitation after reaction. Instead, the solution is centrifuged or filtered, the supernatant is collected, and diluted to run in LC-MS.

Do you recommend any cleanup procedure after the reaction before running on the LCMS? Any recommended solvent to re-dissolve MDA-DNPH to run on the LC? Thank you