X-ray fluorescence energy-dispersive

Chemical analysis of the metal can serve various purposes. For the determination of the metal-alloy composition, a variety of techniques has been used. In the past, wet-chemical analysis was often employed, but the significant size of the sample needed was a primary drawback. Nondestmctive, energy-dispersive x-ray fluorescence spectrometry is often used when no high precision is needed. However, this technique only allows a surface analysis, and significant surface phenomena such as preferential enrichments and depletions, which often occur in objects having a burial history, can cause serious errors. For more precise quantitative analyses samples have to be removed from below the surface to be analyzed by means of atomic absorption (82), spectrographic techniques (78,83), etc. 

Elemental chemical analysis provides information regarding the formulation and coloring oxides of glazes and glasses. Energy-dispersive x-ray fluorescence spectrometry is very convenient. However, using this technique the analysis for elements of low atomic numbers is quite difficult, even when vacuum or helium paths are used. The electron-beam microprobe has proven to be an extremely useful tool for this purpose (106). Emission spectroscopy and activation analysis have also been appHed successfully in these studies (101). 

Asbestos fiber identification can also be achieved through transmission or scanning electron microscopy (tern, sem) techniques which are especially usefiil with very short fibers, or with extremely small samples (see Microscopy). With appropriate peripheral instmmentation, these techniques can yield the elemental composition of the fibers using energy dispersive x-ray fluorescence, or the crystal stmcture from electron diffraction, selected area electron diffraction (saed). 

Table 8.39 Main features of energy-dispersive X-ray fluorescence spectrometry (EDXRF)...

B. Dziunikowski, Energy Dispersive X-Ray Fluorescence Analysis, Elsevier, Amsterdam (1989). 

Lutz, J. and E. Pemicka (1996), Energy dispersive X-ray fluorescence analysis of ancient copper alloys Empirical values for precision and accuracy, Archaeometry 38, 313-323. 

Fei He, Van Espen PJ (1991) General aspects for quantitative energy dispersive X-ray fluorescence analysis based on fundamental parameters. Anal Chem 63 2237... 

Energy Dispersive X-ray Fluorescence Analysis Preconcentration of Trace Elements Radionuclide X-ray Fluorecence Analysis Voltammetry... 

Chong et al. [742] have described a multielement analysis of multicomponent metallic electrode deposits, based on scanning electron microscopy with energy dispersive X-ray fluorescence detection, followed by dissolution and ICP-MS detection. Application of the method is described for determination of trace elements in seawater, including the above elements. These elements are simultaneously electrodeposited onto a niobium-wire working electrode at -1.40 V relative to an Ag/AgCl reference electrode, and subjected to energy dispersive X-ray fluorescence spectroscopy analysis. Internal standardisation... 

Potts, P.J., Webb, P.C. and Watson, J.S. (1985). Energy-dispersive X-ray fluorescence analysis of silicate rocks comparisons with wavelength-dispersive performance. Analyst 110 507-513. 

Linke, R. and Schreiner, M. (2000). Energy dispersive X-ray fluorescence analysis and X-ray microanalysis of medieval silver coins - an analytical approach for non-destructive investigation of corroded metallic artifacts. Mikrochimica Acta 133 165-170. 

Theory Instruments In energy dispersive x-ray fluorescence spectrometry, a sample is bombarded by x-rays that cause the atoms within the sample to fluoresce (i.e., give off their own characteristic x-rays) and this fluorescence is then measured, identified and quantified. The energy of the x-rays identify the elements present in the sample and, in general, the intensities of the x-ray lines are proportional to the concentration of the elements in the sample, allowing quantitative chemical... 

Elements chosen from the limited NURE multi-element geochemical packages that may be pathfinders for porphyry-style deposits (Lefebure Ray 1995) include Ba, Co, Cu, Mn, Pb, Ti, V, and Zn. Under the NURE program, two analytical techniques were used energy dispersive x-ray fluorescence (Cu and Pb) and neutron activation (Ba, Co, Mn, Ti, V, and Zn). Single element plots and element association plots were generated. Geochemical data for pond sediments collected over the Pebble deposit in 2008... 

Hammerle, R.H. and Pierson, W.R. (1975). "Sources and Elemental Composition of Aerosol in Pasadena, California, by Energy-Dispersive X-ray Fluorescence," Environmental Science Technology, % 1058. 

Hammerle, R. H. and W. R. Pierson. Sources and elemental composition of aerosol in Pasadena, Calif. An energy-dispersive x-ray fluorescence. Environ. Sci. Tech. 12 1058-1068 (1975). 

Danesi et al.96 applied SIMS, in addition to X-ray fluorescence imaging, by using a microbeam (p-XRF) and scanning electron microscope equipped with an energy dispersive X-ray fluorescence analyzer (SEM-EDXRF) to characterize soil samples and to identify small DU particles collected in Kosovo locations where depleted uranium (DU) ammunition was employed during the 1999 Balkan conflict. Knowledge of DU particles is needed as a basis for the assessment of the potential environmental and health impacts of military use of DU, since it provides information on possible resuspension and inhalation. The measurements indicated spots where hundreds of thousands of particles may be present in a few mg of contaminated soil. The particle size distribution showed that most of the DU particles were < 5 pm in diameter and more than 50 % of the particles had a diameter of < 1.5 p.m.96... 

Two hundred twenty four Chinese coins (Song Dynasty, ca. 990-1080 A.D.) were analyzed via energy dispersive X-ray fluorescence spectrometiy for the following elements copper (Cu), zinc (Zn), tin (Sn), lead (Pb), iron (Fe), nickel (NO. manganese (Mn), antimony (Sb), gold (Au), platinum (Pt), palladium (Pd), and silver (Ag). The coins routinely appear to be leaded bronze. However, the amount of lead present in these coins was in many cases significantly higher than expected. 

A Spectrace QuanX energy dispersive X-ray fluorescence spectrometer was used, with a rhodium target X-ray tube, running on fundamental parameters... 

Elemental Compositions of Herodian Prutah, Copper Coins—of the Biblical Widow s Mites Series—via Energy Dispersive X-ray Fluorescence... 

Thirty six small copper coins issued under the authority of Herod Agrippa I were analyzed using energy dispersive X-ray fluorescence spectrometry for copper, zinc, tin, lead, antimony, iron, gold, silver, and several other elements. This series of coins show significant amounts of lead in the coins, but an otherwise unadulterated bronze composition, with very little in the way of trace elements. The metallurgical make up of the samples and implications of the findings are presented here. 

A Spectrace QuanX energy dispersive X-ray fluorescence spectrometer was used, which employed a rhodium target X-ray tube, fundamental parameters software, and pure element standards. Sample excitation conditions were 30kV, 0.10mA, 100 sec count, KaP for Fe, Co, Ni, Cu, Zn, As, Pt, Au, Bi, and Pb, followed by 50 kV, 0.72 mA, 60 sec count, for Pd, Ag, Sn, and Sb. Certified brass samples were run each day prior to sample runs to ensure instrument accuracy and precision. 

Enamel and bone, strontium isotope analysis, 102-104 Energy dispersive spectrometry (EDS), scanning electron microscopy, Seip textiles, 35 Energy dispersive X-ray fluorescence (EDXRF), elemental analyses copper-based coins, 231-245 copper coins, Herodian prutah, 246-257... 

Wegrzynek and Holynska [127] have developed a method for the determination of lead in arsenic-containing soils by energy-dispersive X-ray fluorescence spectroscopy. The correction for arsenic interference is based on the use of an arsenic-free reference sample. 

A numerical matrix correction technique is used to linearise fluorescent X-ray intensities from plant material in order to permit quantitation of the measurable trace elements. Percentage accuracies achieved on a standard sample were 13% for sulfur and phosphorus and better than 10% for heavier elements. The calculation employs all of the elemental X-ray intensities from the sample, relative X-ray production probabilities of the elements determined from thin film standards, elemental X-ray attenuation coefficients, and the areal density of the sample cm2. The mathematical treatment accounts for the matrix absorption effects of pure cellulose and deviations in the matrix effect caused by the measured elements. Ten elements are typically calculated simultaneously phosphorus, sulfur, chlorine, potassium, calcium, manganese, iron, copper, zinc and bromine. Detection limits obtained using a rhodium X-ray tube and an energy-dispersive X-ray fluorescence spectrometer are in the low ppm range for the elements manganese to strontium. 

---