Analysis of eastern coal fly ash using separated sampling and excitation atomic emission spectrometry

Abstract

New methodology is described, using separated sampling and excitation atomic emission spectrometry, for the direct determination of elemental constituency of eastern coal fly ash. This technique uses a controlled-waveform high-voltage spark to sample coal fly ash mixed in a graphite pellet. No dissolution or other form of sample preparation is required. The resultant vapor is subsequently entrained into an inductively coupled plasma and observed spectroscopically. A two-point calibration is employed: British Chemical Standards Firebrick (BCS 315) and a pure graphite pellet are used as the high and low standards, respectively. Results for eight elements (Fe, Al, Ca, Mg, Ti, Na, K, and Si), reported as oxides, show typical accuracy and precision of +/- 5% relative standard deviation. Results for a variety of calculation methods, with and without internal standards and/or constituent normalization, are presented. Problems of volatilization in high sodium ash (e.g., western fly ash) and possible solutions are discussed. Application to a variety of similar matrix samples is discussed.