I have a free acid R-COOH and its salt R-COOM. Both are insoluble in water but soluble in methanol. When their methanol solutions are injected into a HPLC-PDA-MS system, are they going to have the same retention time, the same UV spectra and the same mass spectra?
HPLC column is C18; Mobile phase is 50% water:50% methanol with 0.1% formic acid. PDA wavelength ranges from 200~400nm. The MS is a single quadruple. Ion source is positive ESI.
Dear Dr.
You can conduct an experiment to know if you said is applicable,
Good luck
For the compounds I've ever worked on, they have the same RT in my chromatographic condition. So I assume yours would have the same RT.
Dear Dr.
You can conduct an experiment to know if you said is applicable,
Good luck
do you know the pKa of this acid? For HPLC, mobile phase will likely be pH adjusted such that pH is 2 units lower than pKa of analyte, this would ensure all of your acid is in the undissociated state. Retention will be the same as all your analyte will be in acid form.
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