Correction: Development of a novel X-ray fluorescence instrument equipped with a noble gas filter.

Correction for 'Development of a novel X-ray fluorescence instrument equipped with a noble gas filter' by Tsugufumi Matsuyama et al., Analyst, 2024, https://doi.org/10.1039/d4an00122b.

Depth-selective x-ray diffraction using energy-dispersive x-ray detector and straight capillary optics.

Depth-selective x-ray diffraction (XRD) technique was developed. In this technique, XRD spectra were measured using an energy dispersive (ED) x-ray detector at fixed angles. A straight capillary optic was used to define the incident x-ray beam, and a second straight capillary defined the beam path from the sample to detector. Thereby, only the XRD spectrum at the small intersection of two capillary optics could be obtained. A depth-selective XRD is possible by changing the sample position in depth. Many XRD peaks appear in a high-energy range more than 10 keV in the ED spectrum. The detection of these peaks will be advantageous for depth analysis because of low absorption in the sample. Depth-selective measurement would be advantageous over general XRD. In this study, depth-selective and ED-XRD spectra are demonstrated for the layered sample, which consisted of film-like Si powder and a muscovite film.

Development of a novel X-ray fluorescence instrument equipped with a noble gas filter.

In X-ray fluorescence (XRF) analysis, which has been used to analyze elements in various samples, it is important to decrease the background (BG) intensity. Generally, BG signals are reduced by inserting metal foils of various types and thicknesses between the X-ray tube and sample as primary X-ray filters. In this study, we developed a unique gas filter-XRF (GF-XRF) instrument to easily reduce the BG effect by changing the pressure of the gas to ensure that the absorption edge of the gas element is slightly lower than the energy of the XRF peak of the target element. The advantage of using a gas is that the gas pressure can be altered easily. To evaluate the performance of this instrument, Ti and Zr were selected as target elements, and Ar and Kr were selected as the filtering gases. When the XRF spectra of the Ti sample were recorded using the Ar gas filter, as the Ar gas pressure increased, the background signal in the energy region of the Ti Kα peak decreased, resulting in an increase in the signal-to-noise ratio (SNR) of that peak. When the Kr gas filter was used, both the SNR and the minimum detection limit of Zr improved. These results demonstrate that the unique GF-XRF instrument is useful for high-sensitivity analyses.

Confocal micro-X-ray fluorescence analysis for difference identification of ceramic samples.

A nondestructive analytical method for difference identification is required in the research fields such as forensic science or archeology. An X-ray fluorescence (XRF) analysis is one of feasible techniques for this purpose. Micro-XRF using an X-ray micro-beam gives elemental distributions by scanning the samples. A confocal micro-XRF (CM-XRF) technique is a unique analytical technique to analyze limited volume. CM-XRF enables elemental depth imaging and elemental profiling in depth nondestructively. Therefore, CM-XRF has been applied for various samples such as industrial samples, paintings, forensic samples, food materials, and human hairs. CM-XRF technique would be a suitable method for difference identification because the CM-XRF gives detailed information on elemental distribution not only on the surface of the sample but also in depth. We developed CM-XRF instrument in the laboratory and applied to two very similar ceramics samples. It showed differences in the intensity profiles of Fe and Mn for blue paintings on the ceramics. In addition, depth elemental analysis revealed different depth profiles especially of Co and Zn for both samples. These results suggest that CM-XRF provides useful information for the identification of ceramic samples.

Elemental analysis of hourly collected air filters with X-ray fluorescence under grazing incidence.

The X-ray fluorescence under grazing incidence condition (XRF-UGI) was applied for the direct analysis of aerosol filters. Particulate matter less than 2.5 microns (PM2.5) was collected hourly on polytetrafluoroethylene filters using a continuous PM monitor with a virtual impactor method. Although the sampling mass is in trace amounts of 5-30 µg, the metallic contents, such as V, Cr, Mn, Fe, Zn, and Pb, can be measured at sub-ng m-3 detection limits. The effects of the non-uniformity and poor flatness of the PM filters were discussed with regard to the measurement repeatability. The relationship between the XRF-UGI intensities and the mass concentrations obtained via conventional X-ray fluorescence (XRF) analysis was confirmed using the fundamental parameter method. Finally, quantification was successfully demonstrated using the XRF-UGI results with the relative sensitivity factors.

High-accuracy total reflection X-ray fluorescence analysis for determining trace elements using substrate cleaned by ammonia-hydrogen peroxide mixture.

Total reflection X-ray fluorescence (TXRF) analysis is one of the useful techniques for determining trace elements. Owing to the high detection sensitivity of X-ray fluorescence in small residues, the hydrophobic substrates are generally used to form dot-type residue. However, when measuring low-Z elements in sample solutions with high concentrations of matrix elements, obtaining sufficient measurement sensitivity can be difficult. X-ray fluorescence is absorbed by the matrix elements, which means that the absorption effect increases in the thicker dried residue compared to the thinner dried residue. To avoid this absorption effect, we have proposed a thin film-type residue. In this study, the glass substrate was treated with an ammonia-hydrogen peroxide mixture (APM). The hydrogen peroxide decomposes organic components, and ammonia slightly etches glass materials. The APM-treated region was limited to a diameter of 6 mm by using a polytetrafluoroethylene mask placed on the glass substrate. As a result, the surface is refreshed to expose the hydroxyl group to make it superhydrophilic. The measured contact angle was 5°. By using the APM-treated superhydrophilic substrate to prepare dried residue, the net intensities in low Z elements were improved. The ratio of Al Kα intensity, calculated as net intensity in the APM-treated substrate divided by it in the hydrophobic substrate, was 2.29. The recovery of each element in the APM-treated substrate was almost 100%; however, recoveries of elements (Al, P, K, and Ca) in the hydrophobic substrate showed significant deviations from 100% (the recovery of Al was approximately 32%). In summary, we successfully improved both analytical sensitivity and accuracy in TXRF analysis by using the APM treated substrate.

High-accuracy determination of trace elements by total reflection X-ray fluorescence spectrometry using freeze-dried specimens.

Total reflection X-ray fluorescence (TXRF) analysis is conducted to determine trace elements in a sample solution, which is dropped onto a substrate and dried. Therefore, the form of the residue affects the quantitative results. The absorption of X-ray fluorescence (XRF) follows the Lambert-Beer law; the absorption effect of XRF in a thick residue (dotted-type residue) is stronger than that in a thin residue (film-type residue). The absorption effect is particularly remarkable during the determination of low-Z elements in a high-elemental concentration solution. In this study, we propose a new film-like-residue preparation process based on the freeze-drying method to obtain accurate TXRF results. The sample solution is dropped onto the substrate and inserted into a chamber. The chamber is cooled using liquid nitrogen; resultantly, an aliquot of the sample is frozen. The chamber is depressurized using a vacuum pump, and the freeze-dried residue is prepared by maintaining the chamber at room temperature. To evaluate the efficiency of the freeze-drying-based method for sample preparation for TXRF analysis, we prepare a multi-element solution containing high-elemental concentration components. For the residue prepared using the freeze-drying method, the relative standard deviations of the quantitative values and the minimum detection limits are improved because the absorption effect is weakened. The sample preparation process based on the freeze-drying method facilitates accurate TXRF analysis of high-elemental concentration solutions and can be applied for the analysis of trace elements in different types of solutions such as environmental water and wastewater.

Direct digestion of human scalp hair on the substrate used for total reflection X-ray fluorescence analysis.

It is important to determine the elemental content of scalp hair to evaluate human health and environmental contamination. Here, a new sample preparation method for total reflection X-ray fluorescence analysis was developed by directly digesting the human hair on the sample holder. A human hair sample was subjected to thermal nitric acid treatment for sample digestion and homogenization. The Zn concentration was estimated to be ~ 1.89 × 102 µg/g. We can evaluate other elements of human hair by using this method.

Improvement of Detection Limits for Particle Contamination by Confocal Configuration in X-Ray Fluorescence Microscope.

Micro X-ray fluorescence (XRF) enables the non-destructive analysis of particle contamination. In this study, we compared the detection sensitivities and the LLD (lower limit of detection) values of micro-metallic particle contaminations on the plastic detected by micro-XRF and confocal micro-XRF. First, to verify the effectiveness of the confocal micro-XRF, we compared the intensities of different shaping copper samples (plate, thin film and particle). The results demonstrated that confocal micro-XRF is more effective than micro-XRF for the detection of micro particles. Second, to compare the SN ratios of different X-ray energies, several micro-metallic particles (Si, Fe, and Cu) set on an acrylic plate were measured by micro-XRF and confocal micro-XRF. It was found that the SN ratios of the confocal micro-XRF when measuring the Si, Fe, and Cu particles were improved to be approximately 14.6, 21.9, and 43.5-times those of the micro-XRF, respectively. It was determined that confocal micro-XRF is more effective for micro-metallic particles in the higher energy region.

Depth Elemental Imaging during Corrosion of Hot-Dip Galvanized Steel Sheet by Confocal Micro XRF Analysis.

The elucidation of the mechanism for steel corrosion under a coating layer has been attracting research attention. Herein, we utilized a confocal micro-X-ray fluorescence (XRF) analytical instrument to conduct non-destructive elemental analysis near the surface of a steel sheet. Using this method, elemental map images of steel sheet cross sections were obtained without sample destruction. To confirm corrosion suppression in the presence of Mg ions, we observed the corrosion behavior of hot-dip galvanized steel sheets immersed in an aqueous NaCl solution to which Mg ions were added. By using the confocal micro XRF system, the elution of the coating components and the precipitation process of the corrosion products were confirmed.

Development of Methods to Evaluate Several Levels of Uranium Concentrations in Drainage Water Using Total Reflection X-Ray Fluorescence Technique.

As a country's law stipulates the effluent standard uranium concentration in drainage water, the uranium concentration must be determined when drainage water is released from a uranium handling facility, such as the Fukushima Daiichi nuclear power plant. The maximum allowable limit for uranium release at each facility is defined taking into consideration the situation of the facility, such as 1/10 to 1/100 of this effluent standard value. Currently, the uranium concentration of drainage water is commonly determined by α-particle spectrometry, in which several liters of drainage water must be evaporated, requiring about half of a day followed by 2-3 h of measurements, due to the low specific radioactivity of uranium. This work proposes a new methodology for the rapid and simple measurement of several levels of uranium in drainage water by a total reflection X-ray fluorescence (TXRF) analysis. Using a portable device for TXRF measurements was found to enable measurements with 1/10 the sensitivity of the effluent standard value by 10 times condensation of the uranium-containing sample solution; a benchtop device is useful to measure uranium concentrations <1/100 of the effluent standard value. Therefore, the selective usage of methods by a portable and benchtop devices allows for screening and precise evaluation of uranium concentrations in drainage water.

Rapid detection of heavy elements in blood extracted from wounds using x-ray fluorescence analysis.

In radiation emergency situations involving persons having plutonium (Pu)-contaminated wounds, rapid assessment of the degree of Pu contamination is required to determine the appropriate course of treatment. Currently, rapid on-site detection of Pu is usually performed by analysis of α-particles emitted from the adhesive tape peeled off the wound. However, the detection of α-particles is difficult, especially in traumatic skin lesions with oozing blood, because of the low permeability of α-particles in blood. Therefore, we focused on x-ray fluorescence (XRF) analysis because x-rays easily pass through several millimetres of blood. In this study, we developed a new methodology for the rapid detection of heavy elements in wounds based on XRF analysis of the contaminated blood collected by gauze patch and filter paper, using stable lead (Pb) as a model contaminant substitute for Pu. Mouse blood samples contaminated with Pb were dropped on gauze patches or absorbed by filter papers and were subjected to XRF measurement. Small pieces of filter paper served as more suitable extraction materials than gauze patches because the entire amount of blood absorbed could be measured. When we used filter paper, the signal intensity of the Pb Lα peak was proportional to the Pb concentration in the blood. With a measurement time of 30 s, the minimum detection limit of Pb in blood collected by filter paper was 2.4 ppm.