Analytical Note Rapid quantitative determination of major and trace elements in silicate rocks and soils employing fused glass discs using wavelength dispersive X-ray fluorescence spectrometry A. Keshav Krishna ⁎, Tarun C. Khanna, K. Rama Mohan CSIR-National Geophysical Research Institute, Council of Scientific & Industrial Research, Hyderabad, India abstract article info Article history: Received 13 January 2016 20 June 2016 Accepted 6 July 2016 Available online 7 July 2016 This paper introduces a calibration procedure and provides the data achieved for accuracy, precision, reproduc- ibility and the detection limits for major (Si, Al, Fe, Mn, Mg, Ca, Na, K, Ti, P) and trace (Ba, Cr, Cu, Hf, La, Nb, Ni, Pb, Rb, Sr, Ta, Th, U, Y, Zn, Zr) elements in the routine analysis of geological and environmental samples. Forty-two rock and soil reference materials were used to calibrate and evaluate the analytical method using a sequential wavelength dispersive X-ray fluorescence spectrometer. Samples were prepared as fused glass discs and analysis performed with a total measuring time of thirty-one minutes. Another set of twelve independent reference ma- terials were analyzed for the evaluation of accuracy. The detection limits and accuracy obtained for the trace elements (1–2 mg/kg) are adequate both for geochem- ical exploration and environmental studies. The fitness for purpose of the results was also evaluated by the qual- ity criteria test proposed by the International Global Geochemical Mapping Program (IGCP) from which it can be deduced that the method is adequate considering geochemical mapping application and accuracy obtained is within the expected interval of certified values in most cases. © 2016 Elsevier B.V. All rights reserved. Keywords: Multielemental analysis Silicate rocks Soils WDXRF 1. Introduction Silicate rocks, soils and sediments have a complex matrix composi- tion and their multi-element chemical analysis is of interest in several geochemical and environmental applications [1]. Concerning the ana- lytical technique for solid form multi-element analysis, probably X-ray fluorescence spectrometry is one of the most appropriate. But, analytical precision and the ultimate accuracy of the results depend on several fac- tors: instrumental settings and stability, the calibration procedure, min- eralogical and matrix effects, the reference materials used to calibrate the instrument, sample preparation and the strategy adopted to main- tain the results within accepted limits [2]. In geochemistry, we often need accurate measurement of trace ele- ments on a large number of samples, for example in order to study mag- matic processes such as crystallization or partial melting. Usually L spectra have been used as the analytical line for heavy element analysis such as rare earth elements like Th and U, instead of the most intense K spectra, because of their excitation energy is higher than that of primary X-rays [3]. For the quantitative determination of major and trace elements the pressed pellet method is used, whilst the fused bead method is prescribed for accurate analysis of matrix elements. Pressed pellets are prepared from a dried and fine grinded sample in the pellet press after mixing the sample with a binder such as wax. Fused discs are prepared using a fusion apparatus after addition of a suitable flux to the sample. Many authors have examined the fusion techniques involving vari- ous samples to flux ratios such as 1:10 [4,5] 1:5 [6–9] and 1:2 [10–12]. The 1:10 dilution glass discs are suitable for major element analysis, but such a high dilution causes low fluorescent X-ray intensity and con- sequent difficulty in trace element analysis. The 1:5 and 1:2 dilution glass beads are available for both major and trace element analyses. In XRF analysis, borate fusion is particularly advantageous because the ob- tained result is based on a solid glass. In other physical-chemical methods like Atomic absorption (AA) and inductively coupled plasma (ICP) analysis-borate fusion competes with acid digestion techniques and is frequently an easier and simpler way to make liquid solutions. Further, the fused technique is well suited for accurate determination and sensitivities might be improved if the sample-to-flux ratio (dilution ratio) is lowered and the technique eliminates heterogeneity due to grain size and mineralogical effect. With this, a homogeneous molten glass with positive ions of the sample and flux in a cloud of oxygen atoms is formed after cooling to yield an amorphous homogeneous solid glass. The purpose of the present study was to develop a quantitative ana- lytical XRF method for the routine analysis of major and trace elements Spectrochimica Acta Part B 122 (2016) 165–171 ⁎ Corresponding author at: CSIR-National Geophysical Research Institute, Council of Scientific & Industrial Research, Habsiguda, Hyderabad 500 007, India. E-mail address: keshav_aradhi@rediffmail.com (A.K. Krishna). http://dx.doi.org/10.1016/j.sab.2016.07.004 0584-8547/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Spectrochimica Acta Part B journal homepage: www.elsevier.com/locate/sab