From: anish ganesh (anishganesh$##$yahoo.com)
Date: Thu Nov 16 2006 - 18:20:50 EST
1. LC-MS (dharsan sunday)
Dear Mr.Dharsan Sunday
1.What is the difference between Positive and Negative mode and what we found in it in LC-MS?
As explained by others, in positive ionisation we will get the (parent Mass +1) signal and and in negative ionisation, we will get (Parent Mass-1) signal. This is due to difference in protonation and deprotonation. And it depends on the chemistry of the molecule. As the ionisation in LC-MS is soft, we will get Mass+1 peak in positive ionisation mode. Whereas in Normal GC-MS, the ionization is hard ionization/electron bombardment and so the molecular peak won't appear in many cases and only the product (Quan ion) appears.
2.Can we find mass of the compund of unpure compound i.e 70% purity.
Yes, we can find, provided if you have the Reference standard of the compound.
3.Is MS and LC-MS interpetation is same?
If the mentioned MS is the GC-MS, the mass spectra we are getting in GC-MS and LC-MS is different as we are getting molecular ion peak in the LC-MS, whereas in most of the cases we never get molecular ion peak in GC-MS.
Thanks
anish
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