Chromatography Forum

Hello,

I tried a method for aliphatic amines with liquid injection and internal standard. The ratio between area of aliphatic amines and internal standard is not stable (RSD ~5%) from injection to injection (from the same vial). Does anybody have any idea, why is this happening?

In my experience, amines are some of the most difficult materials to chromatograph. They adsorb to almost everything. I've really only had what I'd call "good" success with tertiary amines. Some columns are better than others.

It's usually a good idea to post as much information about your analysis conditions and the nature of your sample as you can. There is a lot of experience on this forum and the more information you can provide, the better we can all help you.

What RSD do you consider stable? For some methods 5% is acceptable.

Hello,

I tried a method for aliphatic amines with liquid injection and internal standard. The ratio between area of aliphatic amines and internal standard is not stable (RSD ~5%) from injection to injection (from the same vial). Does anybody have any idea, why is this happening?

Are you using a literature method or did you cook something up?

We usually derivatise amines as a thiourea and analyse as such, typically get quite good reproducibility. I suspect raw primary and secondary amines would have much greater variability for a lot of reasons.