A novel vacuum spectrometer for total reflection x-ray fluorescence analysis with two exchangeable low power x-ray sources for the analysis of low, medium, and high Z elements in sequence

Abstract

The extension of the detectable elemental range with Total Reflection X-ray Fluorescence (TXRF) analysis is a challenging task. In this paper, it is demonstrated how a TXRF spectrometer is modified to analyze elements from carbon to uranium. Based on the existing design of a vacuum TXRF spectrometer with a 12 specimen sample changer, the following components were renewed: the silicon drift detector with 20 mm(2) active area and having a special ultra-thin polymer window allowing the detection of elements from carbon upwards. Two exchangeable X-ray sources guarantee the efficient excitation of both low and high Z elements. These X-ray sources were two light-weighted easily mountable 35 W air-cooled low-power tubes with Cr and Rh anodes, respectively. The air cooled tubes and the Peltier-cooled detector allowed to construct a transportable tabletop spectrometer with compact dimensions, as neither liquid nitrogen cooling for the detector nor a water cooling circuit and a bulky high voltage generator for the X-ray tubes are required. Due to the excellent background conditions as a result of the TXRF geometry, detection limits of 150 ng for C, 12 ng for F, and 3.3 ng for Na have been obtained using Cr excitation in vacuum. For Rh excitation, the detection limits of 90 pg could be achieved for Sr. Taking 10 to 20 μl of sample volume, extrapolated detection limits in the ng/g (ppb) range are resulting in terms of concentration.

A comparative study on the total reflection X-ray fluorescence determination of lowZelements using X-ray tube and synchrotron radiation as excitation sources

“…All the samples prepared were analyzed by using a laboratory low Z –high Z TXRF spectrometer and at the XRF beamline of Elettra Sincrotrone Trieste, Italy.…”

“…The use of a vacuum chamber TXRF spectrometer such as the WOBISTRAX is well suited for low Z elemental analysis in different matrices, and its analytical performance and applicability have been demonstrated in various applications. However, the attained detection limits for low Z elements are still relatively high …”

“…The study includes the evaluation of accuracy and precision of the TXRF measurements, as well as the determination of the respective low Z detection limits in comparison with an advanced laboratory low Z –high Z novel TXRF spectrometer. The laboratory TXRF spectrometer has been described elsewhere, and it is equipped with a Cr tube for the analysis of low Z elements and an Rh one for medium and high Z elements. The results of this study are expected to provide insights for further optimization of laboratory‐based TXRF spectrometers for low Z elemental analysis of samples and to better identify any instrumental and methodological limitations in various application fields.…”

Improved approach for the determination of low‐Z elements in uranium samples using a vacuum chamber TXRF spectrometer

“…The details of the instrument are given in section Instrumentation and elsewhere. [10,18] In the present study, we beneficially exploited the advantageous features of this instrument for the determination of low-Z elements to get better analytical results for their determination in Certified Reference Materials (CRMs) of uranium oxides. More specifically, we have carried out an extensive solvent extraction process for complete separation of uranium from the CRM solutions, so that most of the uranium is removed from it and the U M escape peaks intensities are either absent or are so small that they do not affect the results of Al and other low-Z element determinations.…”

“…For TXRF measurements, a low Z -high Z TXRF spectrometer (Atominstitut, Vienna, Austria) [10,18] was used. It consists of two low-power X-ray tubes (50 watt power): Cr-target and Rh-target fitted with multilayers Ni/C and Pd/B 4 C and optimized to diffract Cr Kα and Rh Kα lines, respectively.…”