Tube-excited Energy-dispersive X-ray Research Articles

X-ray fluorescence analysis of cultural artefacts — Applications to the Czech heritage

X-ray florescence analysis is an excellent non-destructive tool for analysing the elemental composition of materials in a wide range of works of art. The Department of Dosimetry and Application of Ionising Radiation at CTU-FNSPE has used radionuclide or X-ray tube excited energy dispersive X-ray fluorescence for many kinds of artefacts, including frescos, paintings, manuscripts, metal sculptures and other objects, ceramics, jewellery, various archaeological finds, etc. The method used is more or less “traditional”, i.e., semiconductor spectrometry of excited X-rays, with some optional choices—capillary optics for collimation of exciting beams and two-dimensional scanning. The “hardware” complex is supplemented by techniques for estimating the depth distribution of measured elements, for suppressing surface effects, for in situ non-contact measurements, etc. Extending the measurable range to lighter elements and decreasing the detection limits is one of the achievements that has been attained by improving the instrumentation and techniques that are used. This paper gives a brief review of works carried out at the Department of Dosimetry and Application of Ionising Radiation at CTU-FNSPE.

Heavy Metals in Soil, Grape, and Wine

The elemental concentrations of nine elements (V, Cr, Mn, Fe, Ni, Cu, Zn, As and Pb) were determined in soil, grape and wine samples taken from the wine producing area of Vrbnik on the island Krk in the northern Adriatic) using the tube excited energy dispersive X-ray fluorescence, EDXRF method. Extensive grape cultivation in Vrbnicko polje through the years approximately doubled the Cu content in the soil from this area compared to the background level determined on Krk. Most of this total Cu is exchangeable and thus available to plants. The concentrations of all other elements are similar to those found in the Krk soil. Canonical analysis showed that the main source of heavy metals in grape was absorption from the soil. Statistically significant differences in elemental composition between red and white wine were found. All elements showed greater concentrations in red grape. In spite of the elevated Cu level in the soil, the content of this metal in wine was much lower than the allowed value.

Elemental concentration analysis in soil contaminated with recyclable urban garbage by tube-excited energy-dispersive X-ray fluorescence

Soil and radish (Raphanus Sp) samples from areas treated with organic compost of recyclable urban garbage were quantitatively analyzed by using tube-excited energy-dispersive X-ray fluorescence analysis. Soils treated with 10, 20 and 30 t/ha of recyclable urban garbage and control soil were analyzed. The layer soils were collected at 0–5, 5–10, 10–20, 20–40, 40–60 cm depth. It was possible simultaneously to determine the elemental concentration of various elements: K, Ca, Ti, Mn, Fe, Cu, Zn, Br, Rb, Sr, Zr and Pb in recyclable urban garbage, soil treated with organic compost of recyclable urban garbage and radish plants cultivated in these soils. The elemental concentration of K, Ca, Ti and Fe were determined at percent level (macro-elements) and the other elements at ppm level (micro-elements). It was also possible to observe a significant increase in the contents of K, Ca, Zn, Rb, Sr, Zr and Pb in the soil treated in comparison with the control soil and it was also verified whether the transport of these elements to radish plants cultivated in these soils occurred.

Analysis of Jamaican soils and sediments by energy-dispersive X-ray fluorescence spectrometry

The calibration of a tube excited Energy-Dispersive X-Ray Fluorescence spectrometer for routine geochemical analyses of Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Rb, Sr and Pb in Jamaican soils and sediments is described. Simple linear and parabolic regression models using scattered radiation and an element as internal standards were applied. The analysis of over 200 samples from a regional soil survey has been used to contribute to a database on the geochemistry of Jamaican soils and sediments. An application example of the Zn distribution map in Jamaican soils is presented.

The application of XRF analysis in the determination of113mCd

The overall recovery of the separated113mCd with added Cd carrier from 50 l samples of natural water was determined by a secondarysource tube excited energy dispersive X-ray fluorescence spectrometer measuring the amount of cadmium in the final CdS+CuS coprecipitate on a 25 mm diameter Millipore filter. The method enables to determine 1–20 μg Cd in 100 sec. with a limit of detection of 0.8 μg.

First experiences with a tube-excited energy-dispersive X-ray fluorescence in field laboratories

An energy-dispersive X-ray fluorescence system, equipped with air-cooled X-ray tube, Si(Li)-detector, a 20-sample changer, and a minicomputer was adapted to a mobile laboratory, installed in a Landrover 109. With this system different conditions for the excitation of characteristic lines of trace elements were tested and compared with the qualities of a previously used radionuclide-excited system. Up to 18 elements can be determined simultaneously in the course of one measurement (K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Ga, As, Rb, Sr, Y, Zr, Nb, W, Pb, and Th). For most elements concentrations in common rocks are clearly above the detection limits (e.g., Ni to Pb, 5 ppm; Th, 10 ppm). Two case histories (Kaiserstuhl, F.R.G. and Bastnäs, Central Sweden) demonstrate the applicability of the mobile tube XRF.

Trace-element analysis of Egyptian mummy hair by x-ray fluorescence spectrometry

Quantitative determinations of manganese, iron, copper, zinc and strontium in Ancient Egyptian hair samples were performed by tube-excited energy-dispersive X-ray fluorescence. The hair washing procedure was tested by scanning electron microscopy. A comparison was made between the obtained trace-element concentrations and the corresponding literature data. Particularly different concentration sequences of the examined elements were noted. In modern hair the decreasing order was zinc, iron, copper, strontium and manganese; in Ancient Peruvian hair it was iron, zinc, manganese, strontium and copper; in this work it resulted as iron, zinc, manganese, copper and strontium.

Determination of Sulfur, Ash, and trace Element Content of Coal, Coke, and Fly Using Multielement Tube-Excied X-ray Fluorescence Analsis

A procedure using tube excited energy dispersive x-ray fluorescence analysis with interelement corrections has been developed for multielement analysis of major and trace elements and ash content of coal, coke, and fly ash. The procedure uses pressed pellets and an exponential correction for interelement effects. The average deviations ranged from about 0.0003% for V at an average concentration of about .003% to 0.1% for S at an average concentration of 4%. About 25 elements were measured and 100 second minimum detectable concentrations ranged from about one part per million for elements near arsenic to about one tenth of one percent for sodium.

Tube-excited energy-dispersive x-ray fluorescence analysis : Part I.Comparison with wavelength dispersion

A secondary target tube excited x-ray fluorescence apparatus was compared with a conventional sequential wavelength dispersive spectrometer. Representative samples from the lead industry, an agglomerate for the lead production and a typical air particulate sample collected on cellulose filter were used in the comparison. The following factors were considered: resolving power, spectral interferences, intensity and peak-to-background ratio, sensitivity, reproducibility and precision. The energy dispersive method is advantageous for the multi-element analysis with limited precision of thin samples of environmental composition.

Tube-excited energy-dispersive x-ray fluorescence analysis : Part II. Energy-dispersive x-ray fluorescence analysis of air particulate material

The use of monoenergetic exciting radiation of molybdenum obtained with a secondary target set-up, a conventional water-cooled tungsten anode x-ray tube and a Si(Li) semiconductor detector permits many trace and minor constituents from chlorine to strontium to be determined in particulate material collected on cellulose filters. The method is rapid and economical compared to other multielement techniques. The use of one or more single-element thin-film standards to calibrate for the analysis of many elements appears to be possible, but some systematic errors must be prevented. Absorption of the fluorescent radiation is remedied by a simple correction method. The precision and the accuracy of the method were critically examined by independent analysis of a number of samples with instrumental neutron activation analysis and by interlaboratory comparisons on the same samples.