The Influence of the Thermal Conductivity of Electrodes on the Spectrochemical Analysis of Small Samples and Trace Concentrations
In the spectrochemical analysis of small samples (< 10 mg) and of trace concentrations (< 10 ppm), it is not sufficient only to use sensitive electrical excitation conditions and optically well-adapted spectrographs. Another dominant factor is the support electrode, which influences the evaporation process and codetermines the yield of radiation and the line-to-background ratio for a given sample weight. Apart from the influence of the electrode form and chemical reactions, the evaporation and therefore also the spectrum depend on the thermal properties of the electrode material. This can be demonstrated for various electrode materials such as copper, tungsten, carbon, and graphite, which fact brings us to several general conclusions regarding DC-arc analysis and especially the superiority of carbon.
KeywordsGraphite Electrode Iron Powder Trace Concentration Carbon Graphite Spectrochemical Analysis
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