Hydrogen Plasma-Based Medium Pressure Chemical Ionization Source for GC-TOFMS
In this work, a chemical ionization source for gas chromatography is presented operating at medium pressures up to 13 mbar. Primary ions are generated using a low maintenance hydrogen plasma initiated by a helical resonator (HRP) plasma supply. The ion source offers the most common reagent ions for chemical ionization and is heatable up to > 300 °C to ensure GC limited peak shapes even for high boiling compounds.
The ion source is operated on an atmospheric pressure interfaced time-of-flight mass spectrometer from TOFWERK (ecTOF) and is evaluated for nitrogen, methane and isobutane as reagent gas in terms of selectivity, sensitivity, linearity and fragmentation behavior. An especially broad range of ionized compounds was observed using N2H+/N4H+ as reagent in combination with sub picogram limits of detection.