Hey, I am stuck in the separation of sphingoid base isomers (E/Z), is there is any efficient technique to do this?
If the isomers are not in equilibrium with each other, it may be possible to separate them using chiral chromatography columns. With no possibility of UV or fluorescent detection, you can try evaporative light scattering detection (ELSD), mass spec detection, or refractive index detection.
Mr. Gowda,
I have met a photoisomerization study of trifloxystrobin [ref. 1] (below) by UV, showing that E and Z conformers have exhibited only different intensity (e = 15100 l.mol-1.cm-1 (EE); e = 12 400 l.mol-1.cm-1 (ZZ)). There has been found a shifting of 2 nm of the UV-band position.
In this respect I do not expect so effective information about conformational changes E/Z, employing Fs. Furthermore, looking on the structure of sphingoid bases, they cannot be described as good fluorophores. Have you any preliminary theoretical data or other information about their Fs properties?
Accounting for the fact that most of them have only isolated C=C bond/s you could employ rather IR-spectroscopy, than UV or Fs ones to determin these substances quantitatively.
You could read discussion: "Can anyone help me with quantitative analysis of trans fats using FTIR ?" (https://www.researchgate.net/post/Can_anyone_help_me_with_quantitative_analysis_of_trans_fats_using_FTIR). There have been shown IR-characteristics of corresponding cis-, trans- isomers of RHC=CHR.
[Ref. 1] K. Banerjee, A. Ligon, M. Spiteller, Photoisomerization kinetics of trifloxystrobin, Anal. Bioanal. Chem. (2005) 382, 1527-1533
As they are E and Z isomers, there are a number of columns that might work. a chiral column is a possibility, although it may not be needed. The detector is the important part. ELDS or a mass spectrometer would work, as well as a CAD (charged aerosol detector).
As for the column, one can try silica, C18, diol, and others. With silica, one can run a TLC and use water spray or sulfuric acid spray to see the compounds and determine if there is resolution.
Dear Ivanova
Thank you for your answer. Off course there are many methods for quantitative analysis. But my purpose is to achieve the efficient separation. Suppose if you take plant sphingoid bases there many including E/Z, Z, E, Z/E etc.,
Dear Jack
Do you have any reference that shows separation by ELSD or TLC solvent system.
Dear Adam,
Thank you for your suggestions. I am going to try R.I if you have any references please let me know.
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