Calibration of linked scan spectra for tandem double-focussing mass spectrometers

Abstract Fragment-ion spectra of mass-selected precursor ions obtained in tandem double-focussing mass spectrometers are difficult to mass-measure using computer-based data systems. The reasons for this are explored, and a simple new procedure is proposed which requires no changes in scanning characteristics or static values for either magnetic sector. In addition, the method calls for only trivial modifications to standard mass-measurement algorithms. The performance of the method has been evaluated using ions produced both by electron-impact and by fast-atom bombardment, with m / z values up to almost 1400.