Direct microplasma analysis of coals and sorbents for C, H, N, S and mineral element concentrations

An inverse micro-hollow glow discharge was developed and tested for analytic utility against coals and mineral sorbents. Optical emission spectroscopy identified elemental content by atomic spectral signatures and concentrations by the relative intensities of the corresponding electronic transitions. Analyses against a suite of reference coals validated the micro-plasma's analytical utility by linearity of its optical emission intensity with elemental concentration. Capability for measuring inorganic sorbents' composition is also demonstrated. Element specific calibration coefficients (C) were calculated for the major and minor elements of coal and sorbent (C, H, N, S, Ca, Mg, Si, Al, Na, Fe, K). Analytical results using the microplasma system compared favorably with those using standard analytical instruments, such as a CHN analyzer and ICP for mineral elements, but with attendant instrument advantages of size, weight and power, at far lower cost.