BACKGROUND SPECTRAL FEATURES IN ELECTROTHERMAL VAPORIZATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY - MOLECULAR-IONS RESULTING FROM THE USE OF CHEMICAL MODIFIERS

The formation of background polyatomic ions in electrothermal vaporization inductively coupled plasma mass spectrometry is reported. Vaporization temperatures ranging from 800 to 2500-degrees-C were studied. Carbon-containing polyatomic ions interfere with the determination of Mg, Si, Ti, Ca and Cr. Polyatomic ions resulting from the vaporization of ascorbic acid, sodium chloride, magnesium nitrate, nickel nitrate and palladium nitrate chemical modifiers were studied. Microgram quantities of chemical modifier resulted in oxide and argide polyatomic ion intensities equivalent to picogram background equivalent masses for interfered analyte isotopes. In most cases alternative' analyte isotopes free of interference were available. The formation of carbide or nitride modifier molecular ions was not observed. The argon dimer could be used as a diagnostic tool to indicate plasma loading effects and matrix suppression effects resulting from the use of chemical modifiers.