Chromatography Forum

hi,
i'm running a charantin standard to optimize MS conditions. charantin's molecular weight is 576. the problem is i can't see any ion has this m/z value. some ions appear in MS spectrum is 613.381, 429.234, 174.897, 196.879 (high intensity); 379.126, 429.234, 522.592 (small intensity). the mass of 613.381 has the highest intensity in the spectrum. these ions appear in the spectrum at the value that i don't expect. because charantin has a glucose group in its structure. i think it will appear the mass of 577 and 413 (release the glucose group has m/z value at 162). i would like to know what i had done wrong. i'm using MicrOTOF-Q II MS instrument of Bruker.
Some value of MS source:
- Source:
end plate offset: -500V
Capillary: -4500V
Nebulizer: 0.5 Bar
dry gas: 5.0l/min
Dry Temp: 180 C
- TRansfer:
Funnel 1 RF: 200.0Vpp Funnel 2 RF : 200.0Vpp
ISCID Energy: 0 eV Hexapole RF 200.0Vpp
- Quadrupole:
Ion energy: 20 eV Low mass: 100m/z
- Collision Cell
collision energy: 20eV Collision RF: 150.0 Vpp
Transfer time: 60.0 us (microsecond) Pre puls storage: 4.0us
- Detector:
source: 0V

Please help me. i need your help!

The mass 613.381 may be the common ESI- adducts M+K-2H (M+36.9486). I am not sure without having the exact mass of charantin.

You may want to run a CE ramp to find the right CE you need.

thank for your reply!
charantin is a mixture of two compounds: sitosteryl glucoside (C35H58O6) and stigmasteryl glucoside (C35H60O6). I think the mass of 613 is sitosteryl glucoside (M+K). however, i can't see the mass of 615 (stigmasteryl glucoside).

hi thientham,
i'm doing a research about charantin. can u give me suggestion for any supplier companies which can provide me charantin hplc standard 99%?i find it difficult to find the charantin hplc standard.

thanks.

collision energy: 20eV
The value is too high in my thought, the compound might be broken under such high energy.
Another thing is that you should always have control, e.g., a blank run, to be certain of that the signals are from your sample instead of the system.

hi thientham,
i'm doing a research about charantin. can u give me suggestion for any supplier companies which can provide me charantin hplc standard 99%?i find it difficult to find the charantin hplc standard.

Try http://www.phytolab.com