X-ray fluorescence determination of trace gold in an ion-exchange resin

Abstract

The rapidity of determining trace precious metals in a low density filler is a rather important parameter of the measurement methods used in processing cer tain raw materials. X ray fluorescence (XRF) analysis is one of the better known methods for determining trace impurities and is valued as a relatively simple and nondestructive express method that does not require complicated sample preparation. The use of standard XRF analysis setups for determining trace precious metals is complicated by a strong scattered radiation background: the detection limit for trace impurities is 50-200 ppm, while it is necessary to determine the content of impurities as low as 1-10 ppm. Significant advances in determining trace quantities of precious metals were made with the use of polarized radiation designs where the detection limit C min ≈ 1 ppm [1,2]. However, these designs require complex collimation devices and intense primary radiation sources (~1 kW), and the spectrometers utilizing these designs are bulky and expensive [3]. It was shown in [4] that a high peak to background ratio in the spectra may be obtained even in a simple design with a secondary radiator if it is multilayered with an optimal combina tion of the absorber and radiator functions.The present study is aimed at reducing the gold detection limit in the X ray fluorescence analysis of an ion exchange resin to lower than 1 ppm through the use of portable X ray optics with a secondary radiator [4].The objects under study were reference samples of gold in an ion exchange resin with the gold content of 200, 50, 20, 10, and 0 ppm. The samples in the form of spheres with diameters on the order of 1 mm were arranged in a single layer on 3525 ULTRALENE (SPEX SamplePrep) ultrathin films.The measurements were conducted using a Sprut K (AO Ukrrentgen) energy dispersion spectrometer with an X 100 (Amptek) Si(Li) detector. The mea surement design is shown in Fig. 1. The BS 22 X ray tube with a through type silver target (1) irradiates the yttrium secondary radiator (3) through the 60 μm thick primary radiation filter made of silicon (2). The fluorescence radiation from the reradiator passes through the slit (4), reaches the sample surface (5), and excites the impurity atoms, the analytical lines of which are recorded by the detector (7). The scattering angle 2Θ ≈ 100°, and the aperture of this design is 8 × 10 -6 (X ray target-radiator, radiator-sample, and sample-detector). The X ray tube operating regime is as follows: U = 35 kV, I = 250 μA, and the exposure time is 600 s.Abstract-The use of portable X ray optics with a secondary radiator in the determination of trace gold in an ion exchange resin within the mass fraction range of 1-50 ppm is described. It is shown that the secondary radiator design with primary radiation filtering allows one to determine trace gold in an ion exchange resin when the mass fraction of gold is lower than 1 ppm.

2014 Atomic Spectrometry Update – a review of advances in X-ray fluorescence spectrometry

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Influence of the thermal factor on the composition of electron­beam high­entropy ALTiVCrNbMo coatings

“…Element composition of the samples was examined using the X-ray spectral method at the setup SPRUT-2 (Ukraine). The setup SPRUT-2 is a scanning crystal-diffraction spectrometer, which operates in the wavelength range from 0.035 to 7 nm (from boron to uranium) [37]. Primary excitatory radiation is the radiation from an X-ray tube of the firing type with the Ag anode at excitatory voltage 42 kV [38].…”

Dependence of the Compton to Rayleigh intensity ratio on the scatterer atomic number in the range of 4(Be) to 31(Ga)

“…The corrections are significant in value and make it difficult to rigorously determine the accuracy of measurement results. In previous studies, for the purpose of determining elements with a small atomic number, absolute measurements of the scattering peaks were replaced by measuring the scattering intensity ratio of their integrated scattering intensities. In this case, the correction of experimental data is reduced to a single correction taking into account the difference in the absorption coefficients of the Compton and Rayleigh scattered photons, which are very close in energy.…”

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