Chromatography Forum

hi every body
i want to know what is the main idea behind ms of lc or the basics of ms in case of lc
is it it the same in case of gc but how in case of gc sample introduced in gaseous form but in lc introduce in liquid form:bom:

I am not sure exactly what you want to know - but I'll start here.

Both LC/MS and GC/MS have mass spectrometers as the detectors. With GC/MS, the flow from the column is in gas, typically helium and at a low enough volume that it is not an issue in the ionization process. An EI spectrum of compunds in the stream of gas coming off the column are obtained.

In LC/MS the stream coming off the column is a solvent containing the separated compunds - which must be evaporated to gas phase and there is a lot of solvent present in the ionization process. Thus, LC/MS typically gives a softer ionization method - and spectra with much less fragmentation.

For more details, there is a lot of information available on the internet about the various ion sources and ionization processes that take place with the two types of instruments.

can I recommend you get hold of a textbook such as de Hoffmann and Stroobant, "Mass spectrometry, principles and applications"? This book (and probably many others like it) has good chapters on "hyphenation", the process of attaching a mass spec to some other analytical instrument; why it is useful to do so, what challenges it carries, and how it is done practically.