In-line approaches to introducing ions to mass spectrometers for analysis can inadvertently result in contamination of downstream components because of liquid droplets entrained in the pressure gradient and other potential problems. Scientists at the Pacific Northwest National Laboratory have developed a technology to directly inject ions into an ion guide through the side of the ion guide in a direction perpendicular or orthogonal to the direction of the ion flow through the ion guide.  Injection of ions in this manner has been demonstrated to reduce signal noise and increase signal intensity for low mass ions.  Liquid droplets created by the ionization source that are carried through the capillary into the ion guide are removed from the ion guide by a strong directional gas flow through an inlet opening on the opposite side of the ion guide.  The ion guide can be an ion funnel or ion funnel trap, but can also be other types of ion guides employing RF and DC fields to transmit ions.  The technology includes an insulating shield to prevent discharge between the inlet capillary and the adjacent ion guide electrodes.

The invention is compatible with both single inlet capillaries and multiple inlet capillaries that deliver high gas loads and significantly enhances ion utilization by delivering ions directly into the ion guide. The technology is also compatible with all types of ionization sources and mass spectrometers that incorporate ion guides as a first stage of ion introduction into the mass spectrometer.