AN APPARATUS FOR AND METHOD OF DISCRIMINATING AGAINST UNWANTED IONIZED SPECIES IN MASS SPECTROMETRY WITH COLLISION AND REACTION DEVICES

摘要

A spectrometer apparatus and method provides a modulated stream of ions which can be from the source that is inherently modulated, or a continuous source that is subject to some modulation or gating technique. The ions are then delivered as a pulse or a series of pulses of ions into a pressurized reaction cell, in which reaction and/or collision with gas in the cell occurs. The ions are then passed from the pressurized cell into a mass analyzer for detection. The mass analyzer, ion detector or ion induced signal processing system are operated in such a manner that only ions that arrive at the detector in a period of time set relatively to the time of release of pulses of ions are used for analysis. It has been found that by careful selection of this period, enhanced specificity can be achieved and the effect of interference ions can be reduced.