Polyatomic ions as internal standards for matrix corrections in inductively coupled plasma mass spectrometry

Abstract

Several strong polyatomic ion signals common in inductively coupled plasma mass spectrometry can be used as internal standards to correct for matrix interferences. Signals for most of the polyatomic ions, including metal oxides, are suppressed by a Cs matrix to the same extent as analyte ion signals at nearby m/z values. Examples include ¹⁴N₂⁺ and ²⁴Mg⁺, ³⁵Cl¹⁶O⁺ and ⁵⁵Mn⁺, ⁴⁰Ar¹⁶O⁺ and ⁵⁹Co⁺, ³²S¹⁶O⁺ and ⁴⁵Sc⁺, ⁴⁰Ar₂⁺ and ⁷⁵As⁺, and ⁸⁹Y¹⁶O⁺ and ¹⁰³Rh⁺. The count rates for these polyatomic ions are often measured anyway to determine interference corrections for spectral overlap, so these signals should reduce the number of added elements necessary to correct for matrix interferences.