Use of the Ar2+ signal as a diagnostic tool in solid sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Abstract

The utility of the Ar₂⁺ signal (at mass-to-charge ratio m/z= 80) as a diagnostic tool in solid sampling electrothermal vaporization inductively coupled plasma mass spectrometry (ETV–ICP-MS) is reported. Simultaneous monitoring of the argon dimer signal with the signal(s) of the analyte element(s) indicated that non-spectral interferences, caused by matrix components co-volatilizing with the analyte element(s), can strongly affect the analyte signal profiles in solid sampling ETV–ICP-MS of samples of biological or environmental origin. This observation led to a more profound understanding of why, for a given matrix, the signal profiles strongly differ from one element to another, and why, for a given element, the signal profile is seen to be strongly dependent on the matrix. These matrix effects were also observed to cause a curvature in the sample mass response curves (analyte signal intensity as a function of sample mass). It is shown that, at least in some instances, the use of the Ar₂⁺ signal as an internal standard allows (i) this non-linearity to be corrected for and (ii) accurate analysis results to be obtained. Finally, it is demonstrated that simultaneous registration of the argon dimer and the analyte signal(s) is useful during optimization of ashing and vaporization temperatures.