Performance Comparison Between Two Carrier Gases on a Gas Chromatograph – Mass Spectrometer Using Blank Tube Inlet and Field Ionization
Introduction
The gas chromatograph - high resolution time of flight mass spectrometer (GC-HRTOFMS) is useful for identifying the chemical composition of synthetic compounds and for confirming the molecular weight. Field ionization (FI) is a soft ionization technique suitable for producing molecular ions. The combination of blank tube inlet, where sample is introduced from the GC into the MS by blank capillary tubing, and FI can measure samples in less time than normal GC-MS measurement. In addition, GC-HRTOFMS with FI can be automated using with autosampler. Helium is used as a standard carrier gas for GC separations, however, in recent years, helium supply has become more scarce, resulting in higher prices. As an alternative, N2 or H2 gas can be used instead of He. Nitrogen is plentiful, inexpensive, and safer than H2.
In this study, a blank tube inlet/FI technique using He and N2 as carrier gases was used to identify the chemical composition of an organic synthetic compound and confirm the molecular weight distribution.