Liquid Chromatography-Mass Spectrometry (LC-MS)

Liquid Chromatography-Mass Spectrometry (LC-MS)

1)?Outline?the?principle?of?Electrospray?Ionisation.?In?what?situations?would?you?use?an?alternative?ion?source
(e.g.?Atmospheric?Pressure?Chemical?Ionisation)??Why?is?a?vacuum?required?in?mass?spectrometry?
2)?What?effect?does?working?in?positive?and?negative?ion?mode?have?on?the?m/z?values??Why?was?negative?ion
mode?selected?
3)?What?effect?does?changing?the?collision?energy?have?on?the?MS?sensitivity??What?effect?does?too?high?a
collision?energy?have?on?the?ions?
4)?What?are?the?main?advantages?of?LC?ESI?MS?as?a?tool?for?identifying?compounds??
and?also?mention?that?from?the?results?:
what?type?separation?.?Our?sample?contain?8?different?ions?from?bileacid,?The?last?thing?is?label?the?peaks?on?the?first?picture?in?the?results.

Note:?the?first?chromatogram?on?page?1?is?the?TIC?(total?ion?current)?chromatogram?and?all?of?the?others?are?EIC
(extracted?ion?current)?chromatograms?for?specific?m/z?species.?Importantly,?the?last?EIC?chrom.?on?the?3rd?page
is?the?only?one?you?need?(on?that?page),