Hi,

I am working on 2 unknown natural compounds. I had difficulties to separate one of the other, but I finally got i using basic alumina. Actually, I was to thinking that one of the compounds was decomposating on alumina. However, yesterday I passed a fraction containing the biggest of the two molecules on Sephadex LH-20, with CH2Cl2:THF 99:1 as mobile phase.

I got a surprise this morning after the GC-MS TOF analysis : the second molecule was back in many fractions.

What do you think about that ? I am sure that it is not because the original fraction I used on LH-20 was not concentrated enough to miss the second compound in GC-MS analysis (before the LH-20 column).

However, I found some similarities between the mass spectra of those compounds. I suspect them to contain nitrogen because of the uneven molecular weight, but I can not be sure of the molecular weight because both compound present strange isotopic scheme, with two equal molecular weight peak at 662 and 663 m/z, and a symetric pyramid scheme around them. Some lower masses also present that kind of scheme. The spectrum contain both uneven and even numberred masses.

Does somenone might help me in mass spectroscopy of natural products ?

Thank you,

Fée