What is the difference between sheath, auxillary, drying, and nebulizng gas in a mass spectrometer? Should I make sure that I have all these types of gases for polyphenol analysis via LC-PDA-ESI-MS? For example, previous studies state that they used nitrogen for both sheath and auxillary, can i use nitrogen as nebulizing and drying gas too? Would I still need a colllision gas? Thank you very much. I am very new to LC-MS.