The evolution and applications of multicollector ICPMS (MC-ICPMS)

Abstract

Inductively coupled plasma mass spectrometry (ICPMS) instrumentation has evolved rapidly in the 25 years since the introduction of the first commercial ICPMS instruments. All possible analyzers have been explored (and many commercialized), including magnetic sector (single and double focusing), time of flight, ion trap, triple quadrupole, Fourier transform ion cyclotron resonance (FT-ICR), and Orbitrap, as well as various hybrid analyzers. ICPMS instruments predominantly use quadrupole mass filters, but magnetic-sector ICPMS, in the form of single collector (HR-ICPMS) and multicollector (MC-ICPMS), has garnered a significant portion of the market. Since the introduction of the first MC-ICPMS in 1992 (the Plasma 54 from VG Elemental), 190 MC-ICPMS have been installed in 170 different labs worldwide. The initial hope for MC-ICPMS was that it would simplify measurements normally made with thermal ionization mass spectrometry (TIMS) (e.g., Pb, Sr, Nd, U, Th, Pu, Os) by marrying the favorable characteristics of an ICP source with the precision that can be attained with a multicollector array. While this goal has been largely met, if not exceeded, exploration of the periodic table with MCICPMS has led to the discovery of small but meaningful isotopic variations in nature in a number of elements that were hitherto not accessible or were difficult to analyze. This field is sometimes referred to as “non-traditional stable isotope geochemistry” [1], in contrast to “traditional” stable isotope geochemistry which encompasses the isotopic variations of HCNOS [2], and it includes elements from Li to U. MC-ICPMS, increasingly an essential analytical technique in isotope geoand cosmochemistry, is also expected to find widespread acceptance in other disciplines, such as environmental biology, biochemistry, ecology, and archaeology, to name but a few.