Patent ID: 6107623
Filing Date: 2000-08-22
Classification: H01J

Abstract:
A method of tandem mass spectroscopy comprising the steps of:a) ionizing a sample to generate a population of ions which comprises one or more parent ions;b) passing at least some ions comprised in said population of ions through a mass filter to select only ions having mass-to-charge ratios in a first predetermined range;c) admitting ions selected in step b) to fragmentation means to produce daughter ions from any said parent ions so selected;d) using a discontinuous output mass analyzer, determining whether any daughter ions of interest have been produced by said fragmentation means, and flagging said first predetermined range if any said daughter ions of interest are detected;e) repeating steps b)-d) using different first predetermined ranges until said mass filter has been set to transmit to said fragmentation means all the mass-to-charge ratios which it is thought said parent ions may possess;f) setting said mass filter to transmit to said fragmentation means ions having mass-to-charge ratios in a second predetermined range which comprises one or more of the mass-to-charge ratios comprised in one of said first predetermined ranges flagged in step d);g) determining the mass-to-charge ratios of ions leaving said fragmentation means using said discontinuous output mass analyzer;h) repeating steps f) and g) using different second predetermined ranges until said mass filter has been set to transmit all of the mass-to-charge ratios comprised in all of said first predetermined ranges flagged in step d).