Absorption effects in total reflection X-ray fluorescence (TXRF) analysis are important to consider, especially if external calibration is to be applied. With a color X-ray camera (CXC), that enables spatially and energy resolved XRF analysis, the absorption of the primary beam was directly visualized for mL-droplets and an array of pL-droplets printed on a Si-wafer with drop-on-demand technology. As expected, deposits that are hit by the primary beam first shade subsequent droplets, leading to a diminished XRF signal. This shading effect was quantified with enhanced precision making use of sub-pixel analysis that improves the spatial resolution of the camera. The measured absorption was compared to simulated results using three different model calculations. It was found they match very well (average deviation < 10%). Thus errors in quantification due to absorption effects can be accounted for in a more accurate manner.
The distribution and speciation of zinc were studied in the body of female specimens of the soil-inhabiting, plant-feeding nematode, Xiphinema vuittenezi treated with nano-ZnO and its bulk counterpart. Lyophilized nematodes were studied by X-ray absorption near edge structure spectrometry (XANES) in order to characterize the zinc speciation. Furthermore, in the cross-sections prepared by focused ion beam technique, elemental maps were obtained using the electron probe microanalysis (EPMA) technique. XANES spectra were collected from three different regions (head, midbody and tail region) of nematodes in case of two different treatments (50 mg/L bulk and nano-ZnO suspension, 24 h long treatment). The sample spectra were fitted by the spectra of several reference compounds, the main components of the fitted spectra are the following in all cases: bulk/nano-ZnO; ZnHis and Zn3(PO4)2 * xH2O. Consequently, partial biotransformation takes place for both treatments, histidine- and phosphate-rich ligands play dominant role in the binding of zinc. According to the result of the EPMA analysis, it can be established that the distribution of zinc correlates with the calcium and phosphorus distribution for both treatments. Considering the results of the investigations performed by the two microanalytical techniques, it is likely that calcium phosphate granules were formed in order to bind zinc and hereby to take part in zinc detoxification. Apparent difference in the behavior of bulk and nano-sized ZnO in the body of the investigated nematodes was not found.
This work presents a complex evaluation of a series of Geto-Thracian silver adornments found on Romanian territory, part of the 4th century BC Agighiol (Northern Dobruja) hoard and of an ingot from the 1st century BC Geto-Dacian Surcea (Transylvania) hoard, using Synchrotron Radiation X-Ray Fluorescence and micro- Proton Induced X-ray Emission analysis and mapping in order to investigate aspects related to the elemental composition of the metal and the metallurgy implied in their manufacture. One of the samples can be linked to Laurion as the source of metal, and several items contain silver probably originated in Macedonia. The set of silver items was found to be heteregenous as composition and microstructure, and corrosion-related elements could be also identified in the X-Ray maps.