Polar compound LC-MS/MS - poor peak shape

[A.DeGraw]

I am currently trying to develop an LC-MS/MS method for the quantitation of residual levels of a small molecule in a buffer. The compound does not behave the best chromatographically. I was never able to get retention on a reverse phase column despite multiple attempts with different column chemistries and mobile phases. I ended up going with a Luna 3u NH2 column. My peak shape is terrible though. I am actually getting some peak splitting, but my retention is good (K' for first peak is about six, the second is eight). Does anyone have much experience with amino columns? Any suggestions for improving peak shape? I need sufficient retention to enable diversion of the mobile phase to waste prior to peak elution since the compound will be in buffer (don't want salts on mass spec).

Any suggestions are GREATLY appreciated.

Thanks!

[bisnettrj2]

What compound? What mobile phase? What injection solvent?

[A.DeGraw]

The compound is Kifunensine. The mobile phase is 8:92 Water/ACN + 0.1% NH4OH. The injection solvent is water or buffer at pH 7.3

[bisnettrj2]

Since you're running HILIC, dilute your sample into acetonitrile, reduce your injection volume, or both.

[Alp]

I think bisnettrj2 has the right idea.

You want the sample solvent to be as close to the mobile phase as you can. You might also try going a little higher in acetonitrile, maybe 95 % but if removing all that water from the sample works....
I am curious why you are adding the NH4OH. The molecule is not basic (2 amide groups).
Are you using positive ion mode?
Have you tried a solution of 92/8 ACN/10mM Ammonium Acetate or 92/8 ACN/0.1% formic acid
(you might want to mix it in one bottle).

Good luck
Alp