Inductively coupled plasma mass spectrometry (ICP-MS) with improved signal-to-noise and signal-to-background ratios

A method for operating a collision/reaction cell to suppress interferences in an inductively coupled plasma-mass spectrometry (ICP-MS) system, the method comprising:

• flowing a collision/reaction gas into the collision/reaction cell, the collision/reaction cell comprising an entrance, an exit and a multipole ion guide positioned between the entrance and the exit;
• transmitting ions through the entrance and into the collision/reaction cell, wherein the ions comprise analyte ions and interfering ions;
• applying an exit DC potential at the exit at a first magnitude to generate a DC potential barrier effective to prevent the ions from exiting the collision/reaction cell;
• maintaining the exit DC potential at the first magnitude during a confinement period to perform an interaction effective to suppress interfering ion signal intensity as measured by a mass spectrometer, the interaction selected from the group consisting of:
• reacting the interfering ions with the collision/reaction gas according to a reaction effective to convert the interfering ions to non-interfering ions or to neutral species, wherein the analyte ions collide with the collision/reaction gas a plurality of times effective to slow down and confine the analyte ions in the collision/reaction cell;
• and
• reacting the analyte ions with the collision/reaction gas according to a reaction effective to produce product ions, wherein the product ions collide with the collision/reaction gas a plurality of times effective to slow down and confine the product ions in the collision/reaction cell;
• after the confinement period, transmitting the analyte ions or the product ions to the mass spectrometer by switching the exit DC potential to a second magnitude effective to allow the analyte ions or the product ions to pass through the exit as a pulse having a pulse duration;
• and
• measuring the analyte ions or the product ions for a measurement period having a duration approximately equal to the pulse duration.