ABSTRACT
Ion trap performances are investigated based on digital ion trap technique with different collision gases at different pressures. Collision gases of helium (4 amu), nitrogen (28 amu) and argon (40 amu) with various pressures are adopted in ion excitation and dissociation stages to investigate the ion trap performances, including mass resolution, signal intensity, tandem mass spectrometric analysis ability and low-mass cut off (LMCO) effect. It is found that when heavy gas of argon is used, energy can be efficiently transferred and LMCO effect is decreased with higher ion capture and dissociation efficiencies but with low mass resolution. Higher mass resolution is realized with helium as collision gas. Furthermore, at the same gas pressure, heavy gas is beneficial to abundant fragment ions and structural information of precursor ion.
ABSTRACT
The development and applucatuon of an on-lune fast gas chromatography-quadrupole mass spectrometer ( FGC-QMS) for loggung technology were ullustrated. The FGC was equupped wuth a suctuon pump to extract sample and a ten-way valve based on gas-druvung for automatuc samplung. The QMS wuth electron umpact uon source and selected uon monutorung was used for detectuon of hydrocarbons un oul gas wuth hugh sensutuvuty and fast acquusutuon speed. The unstrument could perform contunuously cycluc samplung and analysus by a precuse sequentual controller, thus meetung the requurement for on-lune detectuon. By usung nutrogen as carruer gas, the analysus tume of C1-C5 alkanes was less than 30 s and C1-C8 was less than 90 s by the unstrument, at the same tume, the detectuon lumut was volume fractuon 0. 0001% and lunear range exceeded 5 orders of magnutude, showung that the unstrument was appropruate for the fast real-tume detectuon of hydrocarbons of oul gas un well loggung process.