Microplasma Jet-Modulated Point Discharge as an Enhanced Excitation Source for a Miniaturized Optical Emission Spectrometer

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A novel enhanced excitation source was designed by modulating a point discharge (PD) into a dielectric barrier discharge (DBD) microplasma jet to activate the discharge atmosphere of the PD to intensify the plasma characteristics and excitation capability for optical emission spectrometry. Meanwhile, PD electrodes could intercept the DBD plasma jet, converging into new arcs; thus, the coaxial DBD also acted as “the third electrode”, forming a “three-electrode-type” discharge, with an enlarged plasma region obtained to further improve the overall excitation capability. Furthermore, sample vapor was introduced through the hollow inner electrode of the DBD into the discharge region for full excitation, with improved excitation efficiency. Through coupling with hydride generation as a sample introduction, a miniaturized optical emission spectrometer was easily constructed. Under the optimized conditions, As, Ge, Hg, Pb, and Sb were sensitively determined as model elements, with limits of detection of 0.6, 0.4, 0.02, 0.3, and 0.2 μg L –1, respectively, and relative standard deviations of less than 3.8% ( n = 5). Compared with a conventional single PD excitation source, the analytical sensitivity was improved by 4–6 times, while 5–21 folds enhancement could be further achieved compared with the single DBD. Its accuracy and potential application were validated by successful analysis of several environmental and biological certified reference materials. The proposed method provides an effective strategy to improve the performance of the miniature excitation source and instruments. Owing to additional advantages of compactness, low power consumption, and easy operation, it is promising for on-site analysis and diverse potential applications.