Optimization of a Vacuum Ultraviolet Photoionization source for Gas Chromatography used with a High Resolution Time of Flight Mass Spectrometer

A soft ion source for GC/MS has been developed and interfaced with a high resolution time-of-flight mass spectrometer. This ion source utilizes a dopant (cyclohexane) to assist the ionization process. However even with a dopant added to the ion source, analyte ions can be generated by several different processes. The goal of this work was to use a tune solution to assist in understanding the effect of source parameters (source temperature, source pressure, and dopant liquid flow rate) on the ionization process. Once the influence of these parameters is understood ion source settings can be tuned for optimal results and/or a specific targeted analysis.