Hi, All,

Could anyone tell me how to get rid of the FMOC-OH and excess FMOC peaks when FMOC was used for the pre-column derivatization?

Thanks a lot in advance!

Jian

We use an amino acid whose derivative comes early to get rid of FMOC-CL, others use 1-amino-adamantane (comes very late). Trouble was produced by FMOC-NH2, we didnt solve that problem as satisfyingly as that from FMOC-OH which was moved out of the range (via mobile phase) of an amino acid of interest.

Iīve read that extracting the alcaline mixture with n-hexane prior to injection FMOC-OH, -NH2 and -Cl could be mostly removed from the sample solution while amino acids (ionized form) would not be extracted.

Check literature

For estimations itīs ok to extract FMOC-Cl, that is, if loosing portions of amino acids doesnīt matter. With FMOC-OH and -NH2 this situation will be considerably worse!
If you are looking at amino acids in body fluids getting FMOC-Cl, -OH, -NH2, under control could be a minor problem.

I once extracting the derivatization mixture with n-hexane several months before. But unfortunately, not only was there some lost of my derivatives (about 20% after 3 extractions), but it had nothing with the excess FMOC-Cl.

As an alternative to FMOC have you considered using Waters AccQTag system/method. Although I haven't used the actual kit, the method of preparation for the aminoquinoyl carbamate has been published and in our lab gave good but variable results with polyamines. The catalogue info offers this as a complete optimised system which Waters say offers improved speed of analysis with better sensitivity. Just to flag up this alternative but might not be of help to you

We have a problem when doing amino acid analysis,precolomn fmoc.The Arg peak starts moving after a few runs and overlaps the Gly peak and only after some more runs it goes out of te Gly.Is there a solution? We use a Merck Superspher-60 rp-8 column