Rapid slurry analysis of solid coal and fly ash samples

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Coal and coal fly ash samples were analyzed as solid slurries. These preliminary experiments used fast sampling STPF procedures which omitted the pyrolysis step and the matrix modifier. The experiments also used an ultrasonic mixing device that automatically stirred the suspension just before the autosampler probe withdrew the aliquot which it would dispense onto the platform. The combination of these techniques made it possible to reduce the analytical time to less than 1 min per sample. Simple aqueous standards were used for calibration. The NIST SRM 1633a Coal Fly Ash was successfully analyzed for As, Pb and Tl, with results for Se in this material that suggested that more work was required to gain confidence in the determination. The SRM 1632a Coal was successfully analyzed for As and Pb. The methods were the same for both materials. A few mg of the dry solid powder was weighed directly into the autosampler cup followed by a weighed amount (about 1.5 ml) of suspending diluent The characteristic mass was calculated from several aliquots of simple aqueous standards and this value was used to calculate the amount of analyte delivered to the furnace. In the work reported here the detection limits for the elements determined were about 0.5–1 μg g in the solid sample. With further experience these limits may be improved. The precision for replicates of slurries from the same cup varied from 2 to 10% depending upon the amount of solid sample delivered to the furnace.