Development of Triple Quadrupole ICP-MS Performance for Difficult Applications

Uwe Noetzel, Agilent Technologies, Waldbronn, Germany
Naoki Sugiyami, Agilent Technologies, Tokyo, Japan
Glenn Woods, Agilent Technologies, Cheadle, United Kingdom

Several important applications in elemental analysis are difficult to address using quadrupole ICP-MS (ICP-QMS). The development of collision/reaction cells (CRC) operating in helium collision mode has improved the removal of polyatomic interferences, delivering improved accuracy for many common applications. But several problematic spectral overlaps remain, including doubly-charged interferences, direct isobaric overlaps, and very intense gas- and solvent-based polyatomics, such as O2, N2, CO, etc.

ICP-QMS can use reactive cell gases to resolve some analyte-interference pairs, but ion-molecule reaction chemistry does not provide a reliable solution when there are many different ions present in the cell. Quadrupole ICP-MS has no mass selection prior to the cell, so cannot prevent non-target ions from entering the cell. Existing ions may interfere with newly formed analyte product ions, or matrix components may form new product ions that overlap the masses of interest. When isotope analysis is performed using reaction mode, inter-isotope overlaps can bias the results, for example 32S18O+ overlaps 34S16O+ at mass 50.

Triple quadrupole ICP-MS (ICP-QQQ) provides a solution to these difficult interferences, using a second mass filter, positioned in front of the cell, to control of the reaction chemistry using MS/MS. With an extended mass range to allow higher-order cluster ions to be measured, a fast detector to support single nanoparticle analysis, and controlled reaction chemistry to resolve interferences including doubly-charged and isobaric overlaps, ICP-QQQ extends the range of ICP-MS analysis to new applications.

In this talk we describe examples from geochemistry, high-purity chemical analysis, environmental monitoring and the nuclear industry, to illustrate the current state of the art in ICP-MS/MS.