Finnigan Corporation

Walter E Reynolds

Paul E Kelley

George C Stafford, Jr

John E Syka

John N Louris

William J Fies

A simple and economical method of mass analyzing a sample by means of a quadrupole ion trap mass spectrometer in an MS/MS mode comprises the steps of forming ions within a trap structure, changing the RF and DC voltages in such a way that the ions with mass-to-charge ratios within a desired range will be and remain trapped within the trap structure, dissociating such ions into fragments by collisions and increasing the field intensity again so that the generated fragments will become unstable and exit the trap volume sequentially to be detected. A supplementary AC field may be applied additionally to provide various scan modes as well as dissociate the ions.

Method of operating ion trap detector in MS/MS mode

The method of operating a quadrupole ion trap in which the mass range of interest is analyzed in segments by trapping ions of successive mass ranges within the segments whereby the operating parameters for each segment may be selected to improve sensitivity and resolution.

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Woodside, CA, United States of America

Walter E Reynolds