Ion optical considerations in tandem mass spectrometry

A review of tandem sector‐field mass spectrometers is given with features of various combinations of electric and magnetic sector fields and quadrupole lenses and, eventually, a Wien filter. In particular, a tandem mass spectrometer is described, constructed at Amsterdam, with post‐acceleration, variable dispersion and array detection. The simultaneously‐detected mass range varies from 1:1.06 through 1:12, the resolution in the second stage amounts to 1000 (single‐focusing), the dynamic range is 5000:1, and the sensitivity is such that less than 1 fmol of sample can be detected and identified.