Microwave‐Induced Plasma Systems in Atomic Spectroscopy

Abstract

AbstractThe use of microwave plasmas as radiation sources for optical atomic emission (AES), absorption (AAS) and fluorescence (AFS) spectroscopy and for laser ionization spectroscopy is treated and reference is also made to the use of microwave‐induced plasmas (MIPs) as ion sources for mass spectrometry (MS). Devices for producing both single‐electrode and electrodeless microwave plasmas are treated, in addition to methods for their diagnostics, and results for the analytically relevant plasma parameters are presented. Methods for sample introduction are discussed. They include dry aerosol generation techniques (hydride generation (HG), electrothermal evaporation, spark and laser ablation (LA)) and possibilities for the uptake of wet aerosols. Special reference is made to coupling with gas chromatography (GC) and also to the potential for coupling with high‐performance liquid chromatography (HPLC) Further, the use of microwave plasmas for cross‐excitation in the case of glow discharges (GDs) is treated. The analytical figures of merit in the case of AES with low‐power microwave plasmas, single‐electrode microwave plasmas, plasma torch sources and stabilized capacitively coupled plasmas are given also in the case of atomic absorption, fluorescence and laser ionization with these sources. The developments in MS in the case of both low‐power and high‐power microwave plasmas and in the case of various types of sample introduction are discussed.Applications of MIP atomic spectroscopy are in the fields of biological samples with special reference to microanalysis, and of environmental samples with special emphasis on metal speciation, on‐line monitoring and direct solids analysis. A critical comparison of the methodology with other methods for the determination of the elements and their species is given.