Patent ID: 9012837
Filing Date: 2015-04-21
Classification: H01J

Abstract:
1. A mass spectrometer comprising: an ion source for ionizing a sample; an ion storage-and-ejection cell having an entrance electrode and exit electrode which performs a storing operation to store at least some of the ions generated by the ion source introduced in the cell through the entrance electrode and performs an ejecting operation to eject the stored ions in pulses through the exit electrode repeatedly opened and closed by signals applied to the exit electrode; a scanning quadrupole mass analyzer to receive said ion pulses from the ion storage-and-ejection cell and to pass through only the ions having the mass-to-charge ratio specified by a mass-selective signal; a detector for detecting the ions passed through the scanning quadrupole mass analyzer; analog signal processing circuitry for converting a signal from the detector into a voltage; an A/D converter for sampling and converting the output voltage from the analog signal processing circuitry into a digital signal; and a computer for generating the pulse signals to be supplied to the exit electrode and for repeatedly generating a scanning mass-selective signal to scan the mass-to-charge ratio of the ions passed through the quadrupole mass analyzer, wherein said computer controls the frequency of the exit electrode pulse signals such that the ejected ion pulses from the storage-and-ejection cell are at least partially overlapped before exiting the scanning quadrupole mass analyzer and while the at least overlapped pulses are passing through the scanning quadrupole analyzer.