Direct Multielemental Trace Determinations in Plutonium Samples by Total Reflection X-ray Fluorescence Spectrometry Using a Very Small Sample Amount

Abstract

A simple, safe, and sensitive method for direct multielemental trace determinations in plutonium samples using total reflection X-ray fluorescence (TXRF) spectrometry has been developed. A very small volume (2 μL) of the sample solutions was deposited on TXRF supports after separation of the plutonium matrix from these solutions. Since the amount of the plutonium deposited on the supports was in the ng level only fixed on the supports and the specimen spots were not disturbed during the sample preparation, the samples could be analyzed directly without putting the instrument in a glovebox. This approach avoided a cumbersome operation of the instrument in a glovebox, which is normally utilized for Pu-based samples using other techniques. Similarly, the requirement of small amounts of the samples minimized the radiation dose to the operator as well as a cumbersome problem of management of radioactive analytical waste of plutonium samples. The samples were analyzed using the TXRF spectra of the specimens, concentration of the internal standard Se or Ga and predetermined sensitivity values. The elemental detection limits for the elements K-Sr varied from 1.06 to 0.09 ng. The elements K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Ba, Tl, and Pb were analyzed at μg/mL level. The analytical results of TXRF determinations showed average relative standard deviation (RSD) value of 4.5% (1σ, n = 3) and the TXRF determined results deviated from the expected values by 5.9% on average for samples prepared by adding multielements in plutonium solutions. Two real plutonium samples were also analyzed in similar manner. For the real plutonium sample solution the average RSD values of TXRF determinations were 10.6% (1σ, n = 3) for the elemental concentrations in the range of 0.2 to 61 μg/mL. These values are comparable with conventional trace element analytical techniques with added advantages mentioned above.

Direct non-destructive total reflection X-ray fluorescence elemental determinations in zirconium alloy samples

“…In addition, XRF analysis has severe matrix effects, and matrix matched calibration standards are recommended for accurate quantitative analysis (Bertin, 2012). Total reflection X-ray fluorescence (TXRF) analysis is a variant of XRF (Misra, 2011;Sanyal & Misra, 2019;Sanyal, Chappa et al, 2018;Sanyal, Dhara & Misra, 2018). Under the TXRF excitation geometry, the exciting X-ray beam is made to fall on the surface of a polished substrate (reflector) at an incident angle much smaller than the so-called critical angle, # crit , for external total reflection resulting in very shallow penetration of the X-ray beam to the extent of only a few nanometres depth within the substrate (Klockenkä mper & Bohlen, 2015;Wobrauschek, 2007;Kregsamer, 1991).…”

“…In the conventional TXRF analysis, a few microlitres of the sample solution are deposited onto a clean quartz sample support along with an internal standard to form a very thin film that poses negligible matrix effect. Although TXRF analysis requires a very small amount of sample, solid samples are required to be dissolved and the major matrix has to be separated to obtain a thin film of the sample, free from matrix effects, deposited on the TXRF support (Sanyal, Dhara & Misra, 2018). Due to the above-mentioned features, TXRF has comparable (even improved in some cases) detection limits with the well established trace element analysis techniques.…”