Patent ID: 7157698

Claim:
A method of operating a mass spectrometer comprising an ion source, an ion trap with a plurality of elongate electrodes, a collision cell and a time of flight analyzer, the method comprising: operating the ion source to generate ions having a relatively broad range of m/z values; introducing the ions generated by the ion source into the ion trap; trapping ions introduced from the ion source in the ion trap; ejecting ions from the ion trap within a relatively narrow range of m/z values substantially orthogonally with respect to the direction of elongation of the electrodes while retaining other ions in the ion trap for subseciuent analysis and/or fragmentation, such that the ejected ions travel to the collision cell; fragmenting ions introduced from the ion trap in the collision cell; ejecting fragmented ions from the collision cell such that they travel to the time of flight mass analyzer; and operating the time of flight mass analyzer to obtain a mass spectrum of ions therein.