This paper reviews the most common methods of generation of plasmas using microwaves with special emphasis on recently developed microwave plasma (MWP) sources for analytical applications. The art and science of microwave plasma optical and mass spectroscopy instrumentation (MWP-OES/MS), and the applications are briefly presented, including very recent advances in the field as of 2012. The design and operation of MWPs is discussed to provide a basic understanding of the most important selection criteria when designing MWP systems. The various plasma generation systems described include single-electrode capacitive microwave plasmas, electrodeless inductively coupled plasmas, multi-electrode systems energized with stationary or rotating fields. We also discuss various technical realizations of MWP sources for selected applications. Examples of technical realizations of plasmas in closed structures (cavities), in open structures (surfatrons, planar plasma sources), and in magnetic fields (Hammer cavity) are discussed in detail. Finally, we mention micro- and mini-discharges as convenient sources for miniaturized spectrometric systems. Specific topics include fundamental aspects of MWP, i.e., recent advances in the construction of analytical MWPs (coaxially coupled cavities, strip-line technology, multi-point energizing, power combining, rotating field-excited plasmas), operational characteristics, analytical characteristics and applications. Special reference is made to coupling with OES for determination of chromatographic effluents and particle sizing. The developments in elemental and molecular MS applications in both low-power and high-power MWPs are also discussed.

The feasibility of the use of the NOVA-2 dual-flow ultrasonic nebulizer for the determination of selenium, antimony and arsenic in drinking and mineral waters by direct hydride generation inductively coupled plasma-optical emission spectrometry (HG-ICP-OES) has been investigated. The acidic sample and the borohydride solution are mixed directly on the surface of a quartz oscillating plate converting liquids into aerosol at the entrance of the spray chamber. The analytical figures of merit for the multielement determination of selenium, antimony and arsenic were evaluated. Results showed that the analytical performance of the new system was superior to that of conventional nebulization systems as well as conventional continuous HG with gas-liquid separation, regarding the susceptibility to non-spectroscopic interferences produced by transition metals. Detection limits between 0.7 and 2.1 ng mL⁻¹ were achieved with ICP-OES detection. The precision of 10 replicate measurements at the 0.25 mg L⁻¹ level was between 1.0 to 1.5% relative standard deviation. The utility of the system was demonstrated in the determination of selenium, antimony and arsenic in hard drinking water ERM-CA011a as well as selenium in mineral water samples. The advantages and limitations of this system, compared with existing techniques, are discussed.