A Controlled-Atmosphere Plasma Arc for Emission Spectrography of Nonmetal Elements
To estimate the weight-percents of certain nonmetal elements in organic compounds found in petroleum reservoirs, the Bureau of Mines designed and constructed a controlledatmosphere plasma arc which effectively excludes air from the plasma. Selected organic compounds that contained nonmetal elements were mixed with a solvent essentially free of those elements. The weightpercents of the nonmetal elements were estimated from the diatomic spectral bands produced; results were reasonably accurate. Analytical working curves were prepared for nitrogen in the range from 15 to 450 micrograms for 100-milligram samples using the analytical carbon-nitrogen band at 3883 A and the internal standard carbon-carbon band at 3607 A. Curves also were prepared for hydrogen, sulfur, and oxygen that had limited sensitivity to detection. Another indicated application of this plasma arc is for characterization of high-boiling petroleum fractions in liquid chromatographic effluents. The rates at which diatomic species are produced and destroyed directly influence the intensity of each corresponding band spectrum.
KeywordsCarbon Tetrachloride Rotational Temperature Band Head Band Pair Residual Nitrogen
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