Synchronized scanning of the first and second mass spectrometers on tandem double-focusing mass spectrometers

A method is described to synchronize the scans of the first and second double-focusing mass spectrometers of a tandem double-focusing mass spectrometer. The scans are synchronized by scanning the first mass spectrometer with voltages instead of the magnetic field. The method is demonstrated with scans that provide all of the precursor ions that produce a selected product ion (precursor ion scan). These precursor ion scans are compared to the previous method of obtaining precursor ion scans on a tandem double-focusing mass spectrometer. The precursor ion scans using the synchronized scanning allow for the use of high-energy collisions on any tandem double-focusing mass spectrometer, while limiting the mass range possible in a single scan. The limited mass range may be corrected by obtaining several spectra with different magnetic fields on the first mass spectrometer.