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VIT C problem
Posted: Wed Feb 11, 2015 2:00 pm
by ydna6969
Hi .
Anybody having issues with retaining vitamin C on a HPLC column , so k prime > 2?
Or if any one has any ideas how to solve this
,, much appreciated
Re: VIT C problem
Posted: Wed Feb 11, 2015 2:14 pm
by HPLCaddict
Browse the column manufacturers databases, there are hundreds of applications out there.
My first choice would be HILIC. Absolutely no problem to retain asorbic acid.
Reversed-phase is not really appropriate here. Only possibility would be ion-pairing, but who wants to do that nowadays?
Re: VIT C problem
Posted: Wed Feb 11, 2015 2:55 pm
by Andy Alpert
Piling on here...
Any decent HILIC column should retain it better than that if you use at least 75% ACN in the mobile phase. Since vitamin C is an acid (pK1 = 4.17), then if you perform the chromatography at a pH high enough for it to be ionized, you should have a concentration of salt in the mobile phase of 20 mM or more in order to shield it from potential electrostatic repulsion by any negative charge that the stationary phase may have. Put the same salt in the sample solvent prior to injection to insure that all the molecules of Vit. C share the same counterions.