I predominantely work with acidified methanol for extractions of plant phenolics. I need a way to get the sample to be less acidic in order to run HPLC and other analyses. Is it possible to evaporate off the acid if I evaporate off the methanol or does the HCl stay concentrated in my dried sample?
It will depend on HCl partial pressure relative to methanol. In practice it will be concentrated in the liquid phase. A solid phase extraction cardridge, C18 or other, can retail phenolicas while HCl is eluted with water, provided the targets are unaffected. Trials with fortified markers are suggested.
You may possibly consider to partially neutralize the acidic methanolic extract with a methanolic solution of either sodium hydroxide or sodium bicarbonate, as long as the salting-out effect of the formed (and dissolved) sodium chloride salt could be accepted; otherwise, it might be possible to reduce its concentration by cooling the partially neutralized extract solution, to crystallize part of the dissolved salt.
The question is easy to solve. Extraction of polyphenols is isually performed by extracting tissues in EtOH/H2O (75/25, v/v) adjusted to pH 2.5 with formic acid. After remivin lipohylivc compounds with n-hexane the ethanol phase is ready to be injected in HPLC. Please check among the other Tattini et al. 2004. New Phytologist. Good work
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