Evolution of rare earth elements, uranium and thorium in geological samples by ICP-OES and their characterization

Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine rare earth elements, uranium and thorium in granitic soils and rock samples collected from Chumporn and Surat Thani provinces, the southern part of Thailand. The effect of digestion temperature (125 degrees C, 160 degrees C, 200 degrees C and 240 degrees C) on the concentration levels of elements was investigated. It was found that the digestion temperature of 160 degrees C had an efficient to leach out the elements to achieve the high concentration of elements for soil samples at different horizons such as O-A, A-B, B-C (1) and B-C(2). For rock sample (D horizon), the digestion temperature did not significantly affect to extract the elements. The results of the analytical study were also compared with the results determined by ICP-MS/OES as obtained from Department of Mineral Resources, Thailand (DMR). A good correlation between the determined values digested at 160 degrees C and the values measured by ICP-MS/OES as obtained from DMR were found for Ce, La, Pr, Nd, Y, Dy, Eu and Th. The SEM-EDS results demonstrated that the samples particles mainly consisted of Si, and Al with varying amount of Fe, K, Mg, Ca, Na and Ti. Quartz and albite were found to exist in all samples that were confirmed by XRD analysis.