Direct Determination of Trace Elements in Graphite Matrices Using Modulated Glow Discharge Atomic Absorption Spectrometry

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Abstract
The trace element concentrations in high-purity graphites were determined by atomic absorption spectrometry (AAS) with the use of a modulated glow discharge atomizer. Glow discharge power was modulated at SO Hz to enhance sensitivity and to permit time-resolved atomic absorption measurements. The influence of discharge operating parameters including current, pressure, and plasma sampling on the analytical performance of this technique was investigated. This analytical technique was evaluated in terms of stability, sensitivity, reproducibility, and accuracy. The method of standard additions was used to determine the impurity levels of the standard graphite matrix. Linear analytical calibration curves were constructed for four elements of interest in samples of nuclear-grade graphite. Detection limits for these elements were calculated to be in the tens of parts-per-billion range for graphite matrices.