The ion funnel technology developed at PNNL by Smith et al. has dramatically improved the ion sampling from sub ambient pressure regions to the low vacuum region. Mass spectrometers that consists of an atmospheric pressure ion source can utilize a standard capillary to transfer ions generated at the source to the ion funnel interface which is typically operated at 1-40 Torr pressure region.A recently developed hybrid ion mobility-mass spectrometer consists of a low pressure drift tube ion mobility device coupled to a high resolution QTOF mass spectrometer. The drift tube is connected to a dual ion funnel system and a desolvation chamber that can accept different types of ionization sources such as ESI, APCI, and nano-ESI. The first funnel, trapping ion funnel and the drift tube are operated at 5.0, 3.8 and 4.0 Torr pressures respectively. The front ion funnel is positioned slightly off-axis to the trapping funnel to reduce gas load to the trapping funnel chamber which improves the pumping efficiency in the system and allows the use of a single mechanical pump. The pressure in the drift tube is maintained at a slightly higher pressure than the trap funnel to eliminate gas from the source region entering the drift tube which helps to maintain the purity of the drift gas as well as to eliminate contamination of downstream ion optics. Both ion funnels are constructed with gold plated printed circuit board (PCB) lenses to reduce the capacitive load to driving electronics. The trapping funnel consists of easily removable grids to facilitate the cleaning and serviceability. An ion funnel with a large entrance aperture which matches with the drift tube lens apertures is utilized to efficiently refocus the diffused ion beam at the exit of the drift tube to improve the ion transmission in the IM-MS interface.

New improvements in ion funnel technology implemented in ion mobility-quadrupole time-of-flight mass spectrometry to achieve highly sensitive and robust instrument platform

248th National Meeting (2014)

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