A method is presented for the rapid (15 to 20 min) analysis of activated carbon from carbon-in-pulp (CIP) plants for its gold content. The method involves the use of microprocessor-controlled energy-dispersive x-ray-fluorescence spectrometer, using excitation by the radioactive isotope 238Pu, and a background-ratio technique to correct for small variations in the matrix. The gold can be determined in dried granular carbon and milled carbon, provided that the calibration standards and samples are in the same physical form. It is shown that, because of the large differences in composition of the matrices of loaded and eluted carbon, two calibration curves need to be established, one for gold concentrations lower than 200 μg/g, the other for gold concentrations higher than 200 μg/g. The calibration curves for milled carbon showed less scattering of the calibration points than those for granular carbon, and the relative standard deviation of the results for milled carbon was 1% as against 2% for granular carbon.
A. M. E. Balaes, "The Rapid Determination of Gold on Activated Carbon by X-Ray-Fluorescence Spectrometry Using Radioactive Isotopes," Appl. Spectrosc. 40, 1190-1194 (1986)