THE ROLE OF CHEMICAL MODIFIERS IN ANALYTE TRANSPORT LOSS INTERFERENCES WITH ELECTROTHERMAL VAPORIZATION ICP-MASS SPECTROMETRY

A modification of a commercial atomic absorption graphite furnace was used as a sampling cell for electrothermal vaporization inductively coupled plasma-mass spectrometry (ETV-ICP-MS). The characteristics of four chemical modifiers used with this ETV-ICP-MS system were evaluated for a suite of 20 analyte elements. Sensitivity enhancements due to presence of the modifiers were observed for all elements. A given quantity of modifier resulted in greater relative enhancements for small analyte amounts than for large analyte amounts. Enhancements were similar for elements of differing volatilities and chemical behavior. This characteristic led to the conclusion that the modifiers acted primarily as physical carriers of vaporized analyte that would otherwise condense on cool surfaces within the ETV cell and on the transport line between the cell and the ICP. The function of modifiers as physical carriers of analyte elements may become as important for ETV-ICP-MS as their traditional graphite furnace atomic absorption role as chemically active reagents. For ETV-ICP-MS devices that exhibit analyte transport loss, modifiers are likely to be a necessary ingredient to successful quantitative results for analyses in which the standards have differing compositions than the samples.