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The development and utilization of collision and reaction cells in atomic mass spectrometry is reviewed. These devices have been used for decades in fundamental studies of ion–molecule chemistry and have only recently been applied in the GD-MS and ICP-MS fields. Such cells are used to promote reactive and non-reactive collisions, with resultant benefits in interference reduction, isobar separation, and thermalizationfocusing of ions in ICP-MS. Novel ion–molecule chemistry schemes, using a variety of reaction gas reagents selected on the basis of thermodynamic and kinetic principles and data, are now designed and empirically evaluated with relative ease. These chemical resolution techniques can avert interferences requiring mass spectral resolutions of >600000 mΔm. Purely physical ion beam processes, including collisional dampening and collisional dissociation, are also employed to provide improved sensitivity, resolution and spectral simplicity. Collision and reaction cell techniques are now firmly entrenched in current-day ICP-MS technology, enabling unprecedented flexibility and freedom from many spectral interferences. A significant body of applications has now been reported in the literature. Collisionreaction cell techniques are found to be most useful for specialized or difficult analytical needs and situations, and are employed in both single- and multi-element determination modes.

The development and utilization of collision and reaction cells in atomic mass spectrometry is reviewed. These devices have been used for decades in fundamental studies of ion–molecule chemistry and have only recently been applied in the GD-MS and ICP-MS fields. Such cells are used to promote reactive and non-reactive collisions, with resultant benefits in interference reduction, isobar separation, and thermalization/focusing of ions in ICP-MS. Novel ion–molecule chemistry schemes, using a variety of reaction gas reagents selected on the basis of thermodynamic and kinetic principles and data, are now designed and empirically evaluated with relative ease. These chemical resolution techniques can avert interferences requiring mass spectral resolutions of >600 000 (m/Δm). Purely physical ion beam processes, including collisional dampening and collisional dissociation, are also employed to provide improved sensitivity, resolution and spectral simplicity. Collision and reaction cell techniques are now firmly entrenched in current-day ICP-MS technology, enabling unprecedented flexibility and freedom from many spectral interferences. A significant body of applications has now been reported in the literature. Collision/reaction cell techniques are found to be most useful for specialized or difficult analytical needs and situations, and are employed in both single- and multi-element determination modes.

A plasma source ion trap (PSIT) mass spectrometer has been modified to incorporate a radiofrequency octopole ion guide/collision cell between the ion source and the mass spectrometer. This modification allows ions sampled from the plasma to undergo reactions prior to mass spectrometric analysis. This capability can obviate the need for chemical or chromatographic separation of the sample, remove mass spectral interferences and enable formation of analytically useful molecular ions. Distinct reaction chemistries can be utilized in the octopole and/or ion trap. Performance of the instrument is dramatically improved if hydrogen gas is introduced into the octopole; molecular hydrogen reacts with Ar+and certain other plasma ions, greatly reduces their intensities, and cools and focuses the ion beam prior to its injection into the ion trap. Selective reactions of atomic ions that are reported include the neutralization of Ar+by reaction with H2and elimination of Y+, Zr+and Xe+by reaction with O2. Thus, 40Ca+can be detected without interference from 40Ar+. Applications to the detection of non‐naturally occurring isotopes include a 200‐fold faster reaction of 90Y+and 90Zr+with O2compared with 90Sr+and a 104‐fold faster reaction of 129Xe+with O2compared with 129I+. Improvements in absolute sensitivity and linear dynamic range of the PSIT‐octopole combination are also presented. Benefits for conventional inductively coupled plasma mass spectrometry (without ion traps) from suitably implemented ion/molecule chemistry are also discussed. © 1997 John Wiley & Sons, Ltd.

Investigations using ion trap devices for analytical atomic spectroscopy purposes have focused on the use of an inductively coupled plasma (ICP) ion source with ion trap mass spectrometric (ITMS) detection. Initial studies were conducted with an instrument assembled by simply appending an ion trap as the detector to a fairly conventional ICP/MS instrument, i.e. leaving an intermediate linear quadrupole between the plasma source and the ion trap. The principal advantages found with this system include the destruction of nearly all problematic and typical ICP/MS polyatomic ions (e.g., ArH +, ArO +, ArCl +, Ar 2 +, etc) and a dramatic reduction of the primary plasma source ion, Ar +. These results prompted the development of a second-generation plasma source ion trap instrument in which direct coupling of the ICP and ion trap has been effected (i.e. no intermediate linear quadrupole); the same performance benefits have been largely preserved. Initial operation of this instrument is described, characterized, and compared to the originally described ICP/ITMS and conventional ICP/MS systems. In addition, experiments aimed at improving ICP/ITMS sensitivity and selectivity using broadband resonance excitation techniques are described. Finally, the potential for laser optical detection of trapped ions for analytical purposes is speculated upon.

A plasma source ion trap (PSIT) mass spectrometer has been modified to incorporate a radiofrequency octopole ion guide/collision cell between the ion source and the mass spectrometer. This modification allows ions sampled from the plasma to undergo reactions prior to mass spectrometric analysis. This capability can obviate the need for chemical or chromatographic separation of the sample, remove mass spectral interferences and enable formation of analytically useful molecular ions. Distinct reaction chemistries can be utilized in the octopole and/or ion trap. Performance of the instrument is dramatically improved if hydrogen gas is introduced into the octopole; molecular hydrogen reacts with Ar⁺ and certain other plasma ions, greatly reduces their intensities, and cools and focuses the ion beam prior to its injection into the ion trap. Selective reactions of atomic ions that are reported include the neutralization of Ar⁺ by reaction with H2 and elimination of Y⁺, Zr⁺ and Xe⁺ by reaction with O2. Thus, ⁴⁰Ca⁺ can be detected without interference from ⁴⁰Ar⁺. Applications to the detection of non-naturally occurring isotopes include a 200-fold faster reaction of ⁹⁰Y⁺ and ⁹⁰Zr⁺ with O2 compared with ⁹⁰Sr⁺ and a 10⁴-fold faster reaction of ¹²⁹Xe⁺ with O2 compared with ¹²⁹I⁺. Improvements in absolute sensitivity and linear dynamic range of the PSIT-octopole combination are also presented. Benefits for conventional inductively coupled plasma mass spectrometry (without ion traps) from suitably implemented ion/molecule chemistry are also discussed. © 1997 John Wiley & Sons, Ltd.