Microanalysis and signature of rare earth elements in geochemical samples using neutron activation analysis

Nuclear techniques are applied for exploration and efficient tapping of natural resources in finding promising resources of mining and mineral processing industries. The rare earth elements (REEs) in four fluorite samples, collected from Nuba Mountains are determined using neutron activation analysis (NAA) technique. The concentration of 11 REEs (Sc, La, Ce, Nd, Sm, Eu, Gd, Dy, Tb, Yb, Lu) was measured and found within ranges between 685 and 1747 ppm. The Ca is a major element in the four samples. The Fe, Al, Na, Ba and Sr are found as minor elements in the investigated samples. In addition, tracer levels of U, Th, Cs, V and Sc are also detected. The signature of Ce, La and Nd as light REEs is characterized in all samples under this study. The enrichment types of light-REEs (L-type), medium-REEs (M-type) and several distinct features of some REEs e.g., Ce and Eu anomalies are identified and described as the signature of REEs in the geochemical samples. These results have demonstrated promising materials that could be used for hydrometallurgy processing to get significant amounts of REEs.

Analytical Processing Development of Tin Element Using Wavelength Dispersion X-Ray Fluorescence (WDXRF) Technique

The aim of this work was to develop technical analysis of wavelength dispersion X-ray fluorescence (WDXRF) and compare with technical neutron activation analysis (NAA). First, the standard of tin oxide (SnO) was ground into powder and mixed with boric acid (H3BO3) as binder at different weight. All of samples were investigated by WDXRF in normalize mode.The results indicated that the range can use to calibration at sample weight 0.2, 0.3 and 0.4 g. Next, the three SnO samples from different area (A, B and C) were ground, mixed with binder at ratio 0.2, 0.3 and 0.4 g and investigated by WDXRF in normalize mode. The results show tin (Sn) content of sample area A, B and C were 75.71, 74.61 and 71.01%, respectively. The result from NAA technique show Sn content of sample A, B and C were 79.36, 77.48 and 73.35%. The percentage error of WDXRF and NAA technique of the samples from the different area had 4.63, 3.70 and 3.19%. From the experiment as examined that the WDXRF technique could be improve process for determine chemical composition which one of choice for easy to used and low cost.

APPLICATION OF MOSS AS BIO-MONITOR FOR HEAVY METALS DEPOSITION IN PORT DICKSON, MALAYSIA

Port Dickson in Malaysia is a sea-side township of mixed activities within the area, comprising of a coal-fired power plant, a petroleum refinery, a gas-fuelled power plant, and tourism with the visit of many road vehicles, especially during weekends and public holidays. The impact of emission from these activities to the environment has becomes a matter of concern to the authorities as well as local residents. The present study embarked on the use of mosses (Octoblepharum sp. & Isopterygium sp.) as long terms monitor of heavy metals emission from such activities. Mosses samples were collected on land area within 30 km radius from the town centre. Prepared samples were analysed for the concentration of As, U, Th, Fe, Cr and Zn using Neutron Activation Analysis (NAA) technique. These metals are related to various industries, fuel combustion and refineries emissions. Although the results show no elevated concentration of the elements studied, except for Cr, the spatial pattern of heavy metal distributions observed reflected the energy-related activities and vehicular emissions in the study area. Enrichment Factor values of each element also in agreement with the distribution pattern. The research finding suggests that ‘moss-method’ is applicable for deposition measurement in vicinity of stationary as well as non-point sources.

The Obsidian Artifacts of Quelepa, El Salvador

Nearly 600 obsidian artifacts dating from about 200 b.c. to a.d. 950 at Quelepa, El Salvador, are assigned to geological source areas using visual criteria and an abbreviated neutron activation analysis (NAA) technique. This combined methodology affords highly accurate results, is inexpensive, and allows large collections to be sourced. Results of lithic analyses describe the evolution of procurement and production strategies at the site. Despite the location of the site on the far southeastern periphery of Mesoamerica, the lithic analyses indicate that Quelepa participated in a Mesoamerican rather than Central American transference network.

Analysis of Foods for Iodine: Interlaboratory Study

An accurate, reproducible method for ≤1 ppm iodine in foods is required for nutritional labeling. In order to ascertain the current status of iodine analysis in foods, 7 samples, representing different food classes, were analyzed by 8 laboratories. Six laboratories used their modifications of the Ce-As-I catalytic method preceded by alkaline dry ashing. Two laboratories used neutron activation analysis (NAA), with differing radiochemical separations. The study showed wide discrepancy in analytical results. Mean relative standard deviation for all laboratories was 77.9% between laboratories; 19.1% within-laboratories. Laboratories using NAA had only slightly better precision than did laboratories using the chemical method. The lowest level reported on the entire group of samples ranged among laboratories from 0.0089 to 0.65 ppm. Figures reported by a laboratory are, in general, consistently high or consistently low. The only differences in methodology which may possibly correlate with level of iodine obtained are the use of NAA technique and use of manual, rather than automated, colorimetry.