ICP-MS ELAN 6100 DRC

ELAN 6100 DRC

The ELAN 6100 DRC (Dynamic Reaction Cell) is the latest model of ICP-MS from PerkinElmer. The instrument was installed in our lab in October 2000. This new model features a Dynamic Reaction Cell (DRC) with Dynamic Bandpass Tuning which removes polyatomic interferences, lowers sample matrix backgrounds, and improves detection limits for many elements.

Polyatomic Interferences

The argon plasma can contain polyatomic ions. Two examples of these polyatomic ions are ions generated by argon itself, argon dimer (Ar₂⁺) and argon oxide (ArO⁺) produced when water is present. With a mass of 80, Ar₂⁺is an interference for the major isotope of selenium (Se). With a mass of 56, ArO⁺ is an interference for the major isotope of iron (Fe). In traditional ICPMS, these interferences are the reasons that less abundant isotopes of Se and Fe are used.

Using isotopes with lower abundances results in lower sensitivities and thus higher detection limits. With traditional

ICP-MS, detection limits for both Fe and Se were approximately 2-20 ug/L due to the argon plasma background and these polyatomic interferences.

Other polyatomic species which present problems for traditional ICP-MS are as follows:

Interference	Analyte
³⁸Ar¹H	³⁹K
⁴⁰Ar	⁴⁰Ca
³⁵Cl¹⁶O	⁵¹V
⁴⁰Ar¹²C	⁵²Cr
²³Na⁴⁰Ar	⁶³Cu
⁴⁰Ar³⁵Cl	⁷⁵As

Dynamic Reaction Cell (DRC)

The DRC is part of the ion optics bench which is under vacuum between the focusing lenses and the analyzing quadrupole (where the isotopes are separated). The cell contains a separate quadrupole to keep the ions focused, and the cell is slightly pressurized with a reaction gas.

In the case of Fe and ArO⁺, the interference is remove by using a reaction gas of ammonia:

ArO⁺ + NH3 -----> ArO + NH3⁺

With the ArO+ removed in the reaction

cell as a neutral species, ⁵⁶Fe⁺ can be determined with much better sensitivity and lower detection limits.

Additional ICPMS publications by WCAS:

Metals Analysis by ICPMS, ICPMS vs.GFAA, ICPMS Metals Screens, Lead (Pb) by Isotope Dilution ICPMS, and "Environmental Analysis Using ICP-MS", Environmental Laboratory, August/September 1993, pg. 44-49. "ICP-MS for the Analysis of Metals on Membrane Filters", American Industrial Hygiene Association Journal, 48(2), pg. 977-979, (1987).

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