Interlaboratory comparison of methane electron capture negative ion mass spectra

Abstract

The electron capture negative ion (ECNI) mass spectra of 12 compounds were measured on quadrupole and magnetic sector instruments. The compounds were selected as examples of molecules that are often examined by ECNI mass spectrometry. Under similar conditions of sample concentrations and ion source temperatures and pressures, the spectra showed good agreement in the molecular ion mass range. A Hewlett-Packard 5985B quadrupole instrument showed a lower abundance of low mass ions (such as Cl/sup -/) relative to the other instruments. Other sources of spectral variability arose from ion/molecule reactions involving reagent gas impurities and from hydrogen incorporation reactions.