Interference Reduction Technology

Inductively coupled plasma – mass spectrometry (ICP-MS) is widely recognized as one of the most accurate and precise analytical techniques for the determination of many trace metals in a wide variety of sample types. However, analyses for a small number of these elements using a conventional instrument configuration have also been persistently challenging due to spectral interferences that can severely compromise the accuracy of reported results.

Brooks Applied Labs has developed numerous matrix and analyte specific methods employing the DRC to produce some of the lowest detection limits and most accurate data available.

These spectral interferences occur due to the formation of polyatomic ions that have the same mass-to-charge ratio (m/z) as the analytes of interest. This  causes erroneously large signals for the intended analyte at the detector and results in unnecessarily elevated detection limits and mistakenly elevated final concentrations.

Polyatomic ions form when the various constituents of the plasma gas, preparation reagents, and the sample matrix combine in the ion beam and prior to reaching the detector. Procedurally introduced elements, such as the argon that fuels the plasma, as well as the chlorine, hydrogen, nitrogen, and oxygen found in the diluents and acids used in sample preparation, unavoidably contribute to the formation of many of these polyatomic ions, even in relatively low level samples.

The analyses of samples that contain abundant amounts of particular elements, such as calcium, carbon, chlorine, magnesium, potassium, sodium, or sulfur, can dramatically further increase the formation of polyatomic ions to levels that can easily exceed even those of the analytes of interest.

In some instances, less abundant isotopes that may not be affected as severely by these interferences can be targeted for detection, but not without the potential for a significant loss in analytical sensitivity. Moreover, the effects of these interferences are not readily apparent by reviewing the results of typical quality control analyses, such as the recoveries of matrix spikes, since the interferences can contribute to each of the analyses equally.

Numerous elements, especially arsenic, chromium, iron, nickel, selenium, and vanadium, are known to be frequently affected by these spectral interferences, with just a few of the common polyatomic ions listed in the table below. Without an analytical technique to eliminate these interferences, costly decisions might be made based on inaccurate data.

A relatively recent advance for overcoming the challenges associated with these interferences, PerkinElmer’s Dynamic Reaction Cell (DRC) improves significantly upon conventional analysis by ICP-MS. Located between the ion optics and the mass analyzer vacuum chambers of an ICP-MS instrument, the DRC is an enclosed and positively pressurized chamber with an independent quadrupole that can be configured to nearly eliminate polyatomic spectral interferences.

To learn more about our innovative analytical methods and how they can benefit your projects, contact us today.

 

Common Interferences

IsotopeAbundancePolyatomic Ions

75As

100%

40Ar35C+, 38Ar37Cl+, 43Ca16O2

52Cr

84%

40Ar12C+, 36Ar16O+, 35Cl16O1H+

53Cr

10%

37Cl16O+, 38Ar15N+, 38Ar14N1H+

56Fe

92%

40Ar16O+, 40Ca16O+, 40Ar15N1H

58Ni

68%

23Na35Cl+, 40Ar18O+, 40Ca18O+

60Ni

26%

44Ca16O+, 23Na37Cl+, 43Ca16O1H+

76Se

9%

40Ar36Ar+, 38Ar38Ar+

78Se

24%

40Ar38Ar+, 38Ar40Ca+

80Se

50%

40Ar2+, 32S16O3+

82Se

9%

12C35Cl2+, 34S16O3+, 40Ar21H2+

51V

100%

34S16O1H+, 35Cl16O+, 38Ar13C+

More information about how ICP-DRC-MS works read our publication on Advanced Analytical Services for ICP-MS with DRC.

Brooks Applied Labs has some of the lowest detection limits commercially available to our clients. View our MDL & MRL Table.