Patent ID: 7741600

Claim:
A mass spectrometer system, comprising: an atmospheric pressure ionization source for forming ions from a sample; an ion transfer tube for transporting ions from the ionization source to a first region, the ion transfer tube extending along a first longitudinal axis; a partition element separating the first region from a second region, the partition element including a skimmer having a cone-shaped protrusion extending into the first region and an aperture communicating from the first region to the second region for transmitting the ions from the first region to the second region; a mass analyzer, disposed in a high vacuum region, for measuring the mass-to-charge ratios of at least a portion of the ions, the mass analyzer and the aperture of the partition element lying along a second longitudinal axis that is offset from or at an angle to the first longitudinal axis; an ion transfer element disposed between the partition element and the mass analyzer, the ion transfer element having an input end for receiving ions that have passed through the aperture of the partition element; and, an ion-deflector at least partially disposed within the second region, the ion-deflector being formed as part of the partition element and having a plurality of electrode surfaces to which a potential difference is applied for establishing an electric field for deflecting ions toward a path approximately along the second longitudinal axis and passing through the input end of the ion transfer element; wherein, during operation of the mass spectrometer, the second region is maintained at a pressure between 2 and 400 millitorr; and wherein the skimmer comprises two separate skimmer portions that are electrically isolated one from the other, such that application of a potential difference between the two separate skimmer portions establishes the electric field for deflection ions.