METHOD AND APPARATUS FOR DISCRIMINATING IONS HAVING THE SAME NOMINAL MASS TO CHARGE RATIO

摘要

Ions of a substance (20) to be analysed are admitted into a mass filter (60) to filter out those ions having all but a limited range of mass to charge ratios. The unfiltered ions pass into an ion trap mass spectrometer (80) which confines the received ions therein. A reagent is also injected into the ion trap (80) and reacts with the ions from the substance to be analysed and/or with ions of the same nominal mass to charge ratio (interferents) arising either from the substance to be analysed as well, or from elsewhere within the system. The reactant products are ejected from the ion trap (80) and detected by an electron multiplier (120). Because ions of the substance to be analysed react with the reagent differently to the interferent ions, different reactant products are generated. This permits discrimination between the original interfering ions.