Isobar Separation in a Multiple-Reflection Time-of-Flight Mass Spectrometer by Mass-Selective Re-Trapping

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Spectrometry

Background:

• Time-of-flight mass spectrometers (TOF-MS) require advanced methods for high-resolution mass separation.
• Isobaric species pose a significant challenge for conventional mass spectrometry techniques.
• Radio frequency (rf) traps offer potential for ion manipulation and selection.

Purpose of the Study:

• To introduce a novel method for ultra-high resolution spatial mass separation in TOF-MS.
• To investigate the dynamic re-trapping technique for enhanced mass selectivity.
• To achieve isobaric separation and improve precursor ion selection.

Main Methods:

• Ions are injected from an rf trap into a TOF analyzer for mass-to-charge ratio dispersion.
• Dynamic re-trapping of dispersed ions within the same rf trap is employed.
• Theoretical treatment and experimental implementation in a multiple-reflection TOF-MS.

Main Results:

• Achieved mass separation powers (FWHM) exceeding 70,000 for caffeine's protonated molecular ion.
• Demonstrated successful separation of isobars glutamine and lysine (mass difference 1/4000) within 0.2 ms.
• Obtained re-trapping efficiencies up to 35%.

Conclusions:

• The dynamic re-trapping method provides highly mass-selective separation in TOF-MS.
• This technique enables isobaric separation and ultra-high resolution precursor ion selection.
• The method holds significant potential for nuclear physics and tandem mass spectrometry applications.