Patent ID: 7932487
Filing Date: 2011-04-26
Classification: H01J

Abstract:
1. A method for analyzing ions, comprising steps of: admitting ions into a fixed inlet end of a first ion selector comprising a first quadrupole mass filter and transmitting through a fixed outlet end thereof only those ions having mass-to-charge ratios within a first selected range; fragmenting the ions transmitted through the first ion selector to produce product ions; admitting the product ions into a fixed inlet end of a second ion selector comprising a second quadrupole mass filter and transmitting through a fixed outlet end thereof only those ions having mass-to-charge ratios within a second selected range; selectively directing the ions transmitted through the second ion selector, or ions derived from the transmitted ions, on a first or a second ion path, the first ion path extending to the fixed inlet end of the first ion selector; combining the ions transmitted through the second ion selector, or ions derived therefrom, with an ion population including corresponding precursor ions; and admitting the combined ions into the first ion selector through the fixed inlet end of the first ion selector; wherein ions traverse the first and second ion selectors only in a forward direction extending from the respective fixed inlet ends to the fixed outlet ends.