Relative merits of two methods of sample introduction in inductively coupled plasma mass spectrometry: electrothermal vaporisation and direct sample insertion

Abstract

Two alternative sample-introduction techniques to conventional nebulisation in analysis by inductively coupled plasma mass spectrometry, namely, electrothermal vaporisation and wire loop direct sample insertion, are compared. Both enjoy certain advantages over pneumatic nebulisation; these include a low sample volume requirement, higher sensitivity and reduced oxide and hydroxide formation. Although introduction by direct sample insertion is not subject to loss of analyte during transport to the plasma, it is less applicable to the analysis of solutions with significant concentrations of salt (higher than 1%) than electrothermal vaporisation is. Performances are compared in the analysis of the river water reference material SLRS-1, directly for Mn, As and Pd and For Au after extraction of the chloride complex AuCl₄^– into isobutyl methyl ketone. Impurities of Fe, Mo and Ni in the wire loop precluded their determination by direct sample insertion.