Elemental analysis with quadrupole mass filters operated in higher stability regions

Operation of quadrupole mass filters in higher zones of stability is described with an emphasis on the potential for elemental mass spectrometry. The higher zones allow a resolution at half height of up to 9000 on atomic ions and make possible unit resolution on ions with kinetic energies up to several thousand electron volts. The theory of quadrupole operation is briefly reviewed. Operation of quadrupoles in the third stability region with Mathieu parameters (a,q)approximate to(3,3) and the second stability region with (a,q)approximate to(0.02, 7.55) is described in detail. Previously unpublished data showing the variation of resolution with ion energy are presented. The variation of transmission with resolution is compared with previous calculations and with new calculations presented here.