Dear Gloria, Folic acid has limited solubility in water (around 1.6 mg/L at 25 C). As a rule you know basic compound dissolve in acidic media and acidic compounds have higher solubility in alkaline media. Folic acis ad its name flag, is an acidic compound and will solve in alkaline media. e.g. Folic acid has around 50 mg/L solubility in 1N NaOH. best mehdi

The folic acid is soluble in 1 M NaOH (50 mg/mL), methanol (slightly), and alkaline solutions. The free acid is only slightly soluble in water (0.01 mg/mL ) and is insoluble in aqueous solutions below pH 5.It is soluble in sodium bicarbonate or sodium hydroxide solutions.

According The Merck Index it is relatevely soluble in acetic acid, phenol, pyridine, and soluble in alkali hydroxy or carbonate solutions

Dear Gloria, Folic acid has limited solubility in water (around 1.6 mg/L at 25 C). As a rule you know basic compound dissolve in acidic media and acidic compounds have higher solubility in alkaline media. Folic acis ad its name flag, is an acidic compound and will solve in alkaline media. e.g. Folic acid has around 50 mg/L solubility in 1N NaOH. best mehdi

DMSO (the best), DMF

DMSO is best solvent for FA also it is good for chemical activation

About the aqueous solubility pH-dependence: J. Chem. Eng. Data 2010, 55, 3958–3961

Is FA stable in alkaline media?

folic acid  can be dissolved in DMSO

Has anyone added 2-mercapthoethanol into solution? How long is stable FA in DMSO? At what temperature do you store it?

I am just doing this ;-)

a 0,4% aqueous solution is no issue at pH >6. Just trying to dissolve gives a pH of around 2, and no it does not work without th NaOH !

Dear Gloria; FA is soluble in DMSO (20 mg/mL) and DMF (10 mg/ml)

is FA or FA's analogue soluble in acetonitrile? Thank you

Folic acid can be dissolved in the media used for cell culture. Because the media contains sodium bicarbonate which is sufficient to completely dissolve the low concentration of folic acid i.e., 0.02 mM recommended for 1L of media (for NK cell culturing). You can even do this while preparing media and filter sterilize the whole media containing folic acid. I did the same for culturing NK-92 cells.

Dear Concern,which buffer do we use to dissolve FA that is to be used in vivo mouse experiment?

Depending on the concentration, Phosphate buffer can dissolve folic acid at low concentration.@Alphonse Umugire

Thank you Oluwesegun for your answer,however I used phosphate buffer without complete dissolving FA.Rather,sodium bicarbonate dissolved FA immediately.