Gold estimation in geological samples using energy dispersive X-ray fluorescence spectroscopy

Gold concentration in Indus river sediments have been estimated using energy dispersive X-ray fluorescence (EDXRF) spectrometry. To get the best possible detection sensitivity, optimisation of sample preparation procedure and exciting radiation was done. Physical preconcentration procedure of panning of heavy minerals has been employed. Samples were dissolved in acqua regia to homogenize the distribution of gold. For obtaining an optimum excitation sensitivity, radioisotope sources of various energies as well as a low power laboratory built transmission type Mo X-ray tube have been used. L shell X-rays of gold have been used for qualitative analysis. For quantitative estimation, a combination of single element fundamental parameter method and scattered radiation standardisation method was used. The sensitivity of EXDRF spectrometer for gold was around 50 ppm. (author). 6 figs., 2 tables