INDUCTIVELY COUPLED PLASMA MICROWAVE-INDUCED PLASMA TANDEM SOURCE FORATOMIC EMISSION-SPECTROMETRY

A tandem source has been constructed by linking an atmospheric-pressur e inductively coupled plasma (ICP) with a reduced-pressure microwave i nduced plasma (MIP). An aerosol of sample solution is introduced into the ICP where it is vaporized and atomized. The resulting analyte atom s are then extracted from the ICP, through a sampling orifice and into a moderate-pressure region in which a microwave discharge is supporte d by a Beenakker-type resonance cavity. It is from this latter dischar ge that analyte atomic or ionic emission is viewed. This paper examine s the analytical characteristics of this pressure-differential tandem source, including optimization studies, background spectra and intensi ty, noise features, chemical interferences, linear range and detection limits. Experimental results indicate that this novel arrangement pro vides some of the expected benefits of a tandem source while other fig ures of merit are only of the same order of magnitude as results obtai ned by conventional ICP atomic emission spectrometry. Unfortunately, i t is found that the microwave plasma adds more background than signal at many elemental emission lines.