Liquid samples are most often introduced into the ICP-MS by an adjustable peristaltic pump. First, a nebuliser generates an aerosol in a spray chamber that allows only the finest aerosol droplets to pass. The sample then enters a high power argon plasma which rapidly desolvates, atomises, and ionises the sample creating a beam of singly charged positive ions.
These ions are rapidly accelerated into the vacuum of the mass spectrometer via the sampler and skimmer cones and accelerating voltages. Ion focusing is achieved by an electrostatic field followed by mass filtering in a quadrupole. The ions are sequentially detected in a single channel electron multiplier.
In DRC mode, a reactive gas (such as ammonia, methane, hydrogen, etc.) is introduced to a pressurised cell between the lens and the quadrupole where fast gas phase chemical reactions take place preferentially between interference ions. The interferences are then removed from the cell by a quadrupole bias while the analyte ions are allowed to pass through the reaction cell.
More information about ICP-MS may be found in the 30 Minute Guide from Perkin Elmer.
Last updated on 17-Sep-08 13:20