Method Development for RP HPLC of Zwitterionic Compounds

[Racrovak]

Hello,

I am attempting to develop a method to separate a mixture of picolinic acid, nicotinic acid, isonicotinic acid, pyridine, N,N-dimethylformamide (DMF), and 1,3,5-trimethoxybenzene. This mixture from a reaction aliquot where the solvent is DMF. I have tried a number of different columns (C8, C18, CN, and phenyl). In the best case I have so far, I have managed to separate picolinic acid, and the 1,3,5-trimethoxybenzene using a 250x4.6mm, 3um C18 column with a gradient elution of MeCN:20mM NBu4OH (pH = 7.5) and 3uL injection volume; however, the DMF, isonicotinic acid, and nicotinic acid seem to coelute and have considerable tailing.

In this case, would it make sense to utilize a mixed mode C18/SCX column such as a Primesep 100 to achieve the desired separation? Or is there a better option?

Thank you for any advise that you can offer!

[Andy Alpert]

Regular HILIC should be able to retain and separate all of those compounds except for 1,3,5-trimethoxybenzene. It may be necessary to use two columns with different modes of chromatography to handle all of the compounds in your sample.

[Vlad Orlovsky]

You can do this with one of our mixed-mode RP/CE columns. You will need to do a gradient of ACN and organic or inorganic acid. I can send you some applications which are not on our website yet.

Check our website for similar applications or contact me through our website.

P.S. I was behind designing and creating all Primesep columns, so I know what you need