Patent ID: 7098452
Filing Date: 2006-08-29
Classification: H01J

Abstract:
1. A system for ion mass spectroscopy comprising: an ion source disposed in atmospheric pressure; a mass spectrometer; a vacuum chamber containing the mass spectrometer; an ion interface disposed between the ion source and the vacuum chamber for introducing ions generated by the ion source into the vacuum chamber for analysis by the mass spectrometer, the ion interface comprising an entrance cell and a particle discrimination cell, the entrance cell having a bore disposed to receive output of the ion source to form an ion stream containing analyte ions and undesirable particulates, the particle discrimination cell having a bore disposed downstream of the bore of the entrance cell and upstream of an aperture in a partition separating atmospheric pressure from the vacuum chamber, the bore of the particle discrimination cell having a central zone and a discrimination zone surrounding the central zone and being sized larger than the bore of the desolvation cell to cause formation of eddies in the discrimination zone when the ion stream flows from the bore of the entrance cell into the bore of the particle discrimination cell, the particle discrimination cell having a voltage applied thereto for generating a discrimination electric field in the bore thereof, whereby the discrimination electric field and the formation of eddies in the particle discrimination cell together provide an effect of removing a portion of the undesirable particulates from the ion stream prior to entering the vacuum chamber through the aperture of the partition.