Inductively Coupled Plasma-Mass Spectrometry (ICP-MS): Interferences

Despite the advantages offered by ICP–MS, accurate elemental analysis is affected by spectroscopic and non-spectroscopic interferences.

Spectroscopic interference is caused by ions with the same m/z values as analyte ions. Interfering species include isobaric species, polyatomic ions, and refractory oxide ions.

Isobaric interference arises from analyte isobars, which are different nuclides that have the same mass number—meaning the m/z values are the same.

Polyatomic ion interference results from the combination of plasma species with matrix or atmospheric species to form polyatomic species which further fragment into molecular ions of the same m/z value as an analyte.

A critical interference arises due to the formation of refractory oxide and hydroxide species from the analyte and matrix species.  

Non-spectroscopic interference includes the matrix effect, which is associated with a high concentration of matrix species and generally causes analyte signal reduction.

Matrix effects can be largely compensated for by using an appropriate internal standard.