Microdischarge in Flame as a Source-in-Source for Boosted Excitation of Optical Emission of Chromium

Abstract

A compact tandem excitation source-in-source was designed by arranging a point discharge (PD) ignited in argon/hydrogen (Ar/H2) flame and utilized for boosted excitation for the optical emission of chromium. Through a tungsten coil (W-coil) electrothermal vaporizer (ETV) located right under the tandem source without any interface for sample introduction, a miniaturized optical emission spectrometer was realized. Because the discharge gaseous atmosphere of PD was activated in the flame, the energy consumption of PD for breaking down discharge gas and maintenance of plasma was greatly saved. In addition, the flame could partially atomize or keep the atomized state of analyte atoms through its reducing environment. Therefore, the excitation capability of the tandem source was greatly improved, owing to the synergistic effect of PD microplasma and Ar/H2 flame. In addition, part of the analyte was atomized/excited on the W-coil, and thereby, dry, pure, and activated analyte species were released from the W-coil and swept into the tandem source for atomization/excitation. Through the collective effect of W-coil ETV, Ar/H2 flame, and PD microplasma, analytical sensitivity for Cr was greatly enhanced. Under the optimized conditions, with 10 μL sample solution, a limit of detection of 1.5 μg L–1 and a relative standard deviation of 3.6% (20 μg L–1, n = 5) were achieved. Its accuracy was demonstrated by successful analysis of several certified reference materials. Owing to the advantages including high sensitivity, compactness, and cost effectiveness, it is promising to facilitate the miniaturized spectrometer for more elements and potential field analytical chemistry.

Array Point Discharge as Enhanced Tandem Excitation Source for Miniaturized Optical Emission Spectrometer

“…Through constructing a cross double point discharge (CrossPD) or a hollow electrode point discharge (HEPD), the enlarged plasma region could enhance the excitation capability and intercept more analyte vapor to be involved in the optical emission excitation. Meanwhile, heating the discharge gas is also an effective way to enhance the microplasma characteristics. ,, Further, by replacing the discharge gas from an inert gas to argon/hydrogen flame, which is full of activated radicals, a synergistic effect of flame and discharge microplasma could be achieved to significantly boost the excitation capability of the PD microplasma for chromium determination …”

“…28,36,39 Further, by replacing the discharge gas from an inert gas to argon/hydrogen flame, which is full of activated radicals, a synergistic effect of flame and discharge microplasma could be achieved to significantly boost the excitation capability of the PD microplasma for chromium determination. 40 In the present work, to further improve the total excitation capability and excitation efficiency of PD microplasma, an array PD (ArrPD) microplasma was designed and arranged in a narrow discharge chamber to be utilized as the intensified excitation source, for tandem excitation and improved excitation capability. It was subsequently coupled with HG for sample introduction to construct a miniaturized optical emission spectrometer.…”

Direct and Sensitive Detection of Mercury in Soil by Portable Electromagnetic Heating Vaporization and Purge-and-trap Followed by Microplasma Optical Emission Spectrometry

“…Compered to LA, ETV is more established for the direct analysis of soil samples due to its effective matrix separation and cost-effective instrumentation. However, the conventional ETV, using graphite, 44 tungsten, 45 molybdenum, 46 rhenium, 47 and other high melting point metals as heating materials, often suffer from low heating efficiencies and high power consumption as sample introduction approaches. To overcome these limitations and adapt ETV suitable for field analytical chemistry, Wang et al 48 and Jiang et al 49 developed an electromagnetic heating vaporization (EMHV) device and employed it in conjunction with microplasma optical emission spectrometry for the direct quantification of Hg, Cd, and Pb in hair and soil samples.…”

Field Detection of Uranyl in Coastal Water of China Using a Portable Device via DNA Photocleavage

“…23,24 Furthermore, Hou and Gong's groups integrated the designed fluorescent MOFs with portable X-ray fluorescence spectrometry or drones to facilitate on-site sampling and detection of uranyl in the environment. 25,26 Besides, based on the unique uranyl-triggered photocleavage activity, the protein labeled with an aggregation-induced emission fluorescent molecule has been successfully used for ultrasensitive analysis of uranyl. 27 However, the complex synthesis process of these nanomaterials and tagged biomolecules also results in multiple operations and high costs.…”