COMPARISON OF PXRF AND ICP-MS DATA IN RESIDUAL SOILS
Use of Portable XRF on Soil Samples
A total of 14,651 un-sieved B- and C-horizon residual soil samples were collected on detailed grids at the Smash Minerals (Prosperity Goldfields Corp) Whiskey gold project in the Black Hills of the Yukon Territory, Canada during the 2011 field season. The samples were dried and analysed directly through the sample bags using two pXRF devices, an Innov-X Delta handheld and a Niton FXL desk top unit. The samples were also analysed by ICP-MS at AcmeLabsfollowing sieving to -100 µm and a modified aqua regia digestion, allowing a direct comparison of pXRF and ICP-MS data by the two methods on the same samples. Data for selected elements from the pXRFs show trends in gridded percentile plots comparable to the ICP-MS data, although the continuity of these trends reflects the degree to which the pathfinder element concentrations exceed the lower orders of detection. Acceptable merged gridded images for As and Cu from the two devices were generated without data levelling, whereas the Pb, Mo and Ni data required levelling for the different instruments prior to gridding. Data for elements close to the lower limit of detection by pXRF, such as Sb, provide limited information and may even be misleading.
This case study is taken from Arne, D.C., Mackie, R.A. and Jones, S.A., 2014, The use of property-scale portable X-ray fluorescence data in gold exploration: advantages and limitations. Geochemistry: Exploration Environment Analysis, 14, 233-244.
Comparison of portable XRF and ICP-MS Data for Selected Elements
Elements such as As, Cu and Pb show good correlations, whereas Sb does not (from Arne et al., 2014).
Comparative maps of arsenic in soils by portable XRF and ICP-MS
Soil data analysed by ICP-MS following sieving to -100 microns and digestion in modified aqua regia acid (left) are compared to pXRF data analysed through sample bags in the field with no sample preparation other than drying (right) (from Arne et al., 2014).