X-Ray Fluorescence Spectroscopy XRF

The chemical composition of particulate pollutants is determined in two forms specific elements, or specific compounds or ions. Knowledge of their chemical composition is useful in determining the sources of airborne particles and in understanding the fate of particles in the atmosphere. Elemental analysis yields results in terms of the individual elements present in a sample such as a given quantity of sulfur, S. From elemental analysis techniques we do not obtain direct information about the chemical form of S in a sample such as sulfate (SO/ ) or sulfide. Two nondestructive techniques used for direct elemental analysis of particulate samples are X-ray fluorescence spectroscopy (XRF) and neutron activation analysis (NAA). 

Acid-digestion is often used with composts derived from municipal wastes, sewage and slurry, where toxic amounts of heavy metals may cause problems on the land to which they are applied. It is probably more convenient to determine total elements in soils by a benchtop X-ray fluorescence spectroscopy (XRF) instrument. This only requires the soil to be ground, and several reference standards of a similar soil. A Reference Materials Catalogue, Issue 5, 1999, is available from LGCs Office of Reference Materials, Queens Road, Teddington, Middlesex TW11 OLY, UK. Tel. -i-44 (0)20 8943 7565 Fax h-44 (0)20 8943 7554. 

X-ray fluorescence spectroscopy (XRF) Wavelength-dispersive XRF Is generally destructive not so energy-dispersive XRF Giauque et al. (1993)... 

Since the mid-1960s, a variety of analytical chemistry techniques have been used to characterize obsidian sources and artifacts for provenance research (4, 32-36). The most common of these methods include optical emission spectroscopy (OES), atomic absorption spectroscopy (AAS), particle-induced X-ray emission spectroscopy (PIXE), inductively coupled plasma-mass spectrometry (ICP-MS), laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), X-ray fluorescence spectroscopy (XRF), and neutron activation analysis (NAA). When selecting a method of analysis for obsidian, one must consider accuracy, precision, cost, promptness of results, existence of comparative data, and availability. Most of the above-mentioned techniques are capable of determining a number of elements, but some of the methods are more labor-intensive, more destructive, and less precise than others. The two methods with the longest and most successful histoty of success for obsidian provenance research are XRF and NAA. 

However, in region A, the chemical composition of the deposited thin films is very sensitive to the minute variation of temperature because in this region the thermal decomposition rate of the Ti precursor is very sensitive to temperature i.e. surface chemical reaction controls the deposition. The variation of mass concentration of the constituent ions estimated by x-ray fluorescent spectroscopy (XRF) is... 

Metals were analyzed using dispersive X-ray fluorescence spectroscopy (XRF) on a SPECTRACE 6000. 2 g of sample were used. For metals in char multi-level calibrations within a range of 10-20,000 ppm were carried out. For the liquid samples the range was set between 1 and 10,000 ppm. 

The structural properties of the samples were characterised by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRFS), nitrogen adsorption and 27Al MAS NMR. The acid properties of the zeolite were also investigated using n-butane cracking as a test reaction. 

X-Ray Fluorescence Spectroscopy (XRF) provides rapid, quantitative analysis of specific chemical elements in... 

Platinum and chlorine (samples made with chloride precursors) contents of the catalyst samples were determined with X-ray fluorescence spectroscopy (XRF) (Phillips PW 1480 spectrometer). BET surface areas of catalysts were within 5% that of the silica support material. Platinum dispersion was measured with hydrogen chemisorption in a volumetric set-up, using a procedure described elsewhere [3]. Stoichiometry of H/Pt = 1 was assumed for calculating the platinum dispersion [4]. Transmission electron microscopy (TEM) (Phillips CM 30, 300kV) was used to check the platinum particle size in some of the catalysts. Average platinum particle size was determined based on analysis of about 100 platinum crystallites. 

X-ray fluorescence spectroscopy (XRF) is much easier in its performance but by no means as reliable particularly in case of low element contents. Here, the dried, mortared and homogenized samples can be used directly as powder, or better in this shape of pressed tablets, or even better still, as molten tablets. With this method, good detection limits are obtained for most of the quantitatively relevant elements, the access to trace metals, however, is not feasible to the same extent as in complete extraction and subsequent analysis of the extract solution. 

Table 2 shows the chemical compositions of the porcelains measured by X-ray fluorescence spectroscopy (XRF 1500, Shimadzu), showing that all porcelains had aluminosilicate compositions with alkali and alkaline-earth metal oxides, besides other minor oxides. For porcelains containing leucite particles (C, D, and B), parts of Si02, AI2O3, and K2O contents composed these particles. Considering the fraction and stoichiometry of leucite (KAlSi206 = K20.Al203.4Si02), the compositions of glassy matrix of these porcelains were calculated and are also shown in Table 2. Note that all porcelains had in the glassy matrix an initial K2O content, and also potentially exchangeable Na ions by K ions from an external source.

X-ray fluorescence spectroscopy (XRF) is another measurement technique for major and minor elemental concentrations, as well as trace elements. However, it has very low sensitivity to elements with atomic number Z < 9. Optical atomic spectroscopy is suitable to analyze solutions, which requires complete dissolution... 

Electrochemical experiments to measure cell voltage and current efficiency are simple, direct, and usefiil for the investigation of membrane performance. Visual and microscopic observations are indispensable. Visual inspection is the principal method used for determining the soundness of the membrane surface. SEM is quite useful for the inspection of morphology of the surface or cross-sections. It can be used to identify deposits of impurities. XRD and X-ray fluorescence spectroscopy (XRF) are useful for the semiquantitative determination of impurity accumulation and distribution [126]. Table 4.8.10 [ 132] sununarizes the reconunended methods for detecting the physical and chemical damage to membranes. 

Of the solid state analysis methods, namely, neutron activation analysis (NAA), X-ray fluorescence spectroscopy (XRF), and arc/spark emission spectroscopy, only NAA has found wide application for manganese analysis of biological samples. Although Birks et al. [102] claim high sensitivity for XRF analysis of manganese in freeze-dried samples, there are problems of standardization of the technique at low manganese concentrations, while solid emission spectroscopy suffers markedly from electrode contamination. On the other hand, NAA has both a high specificity and sensitivity... 

The samples were characterized by X-ray fluorescence spectroscopy (XRFS), X-ray powder dififiaction (XRD), scanning electron microscopy(SEM) and Mossbauer effect spectroscopy(MES). For MES measurements the Co in chromium matrix was served as the source. Isomeric shift values were given in relation to metallic iron. Spectra were computer-fitted and Mossbauer parameters were calculated. 

X-ray fluorescence spectroscopy (XRF) has been used for many years for the measurement of major and minor elemental concentrations. Improvements made in the sensitivity in recent years now allow the technique to be applied to the analysis of trace elements. A problem is that the sensitivity of XRF decreases dramatically for lower atomic number elements so the technique cannot be used for quantification of elements with atomic numbCT Z < 9. When compared to XRF, modern AA or AE instruments are simpla- to use, less expensive, have similar precision of analysis and have bettCT sensitivity. Optical atomic spectroscopy is ideally suited to the analysis of solutions so the method requires complete dissolution of the powder in a liquid. In comparison, XRE is ideally suited to the analysis of solid samples, and this can be a distinct advantage for cCTamic powders that are commonly difficult to dissolve. Table 3.7 includes a summary of the main features of optical atomic spectroscopy and XRF. 

Atomic x-ray fluorescence spectroscopy (17,18), referred to simply as x-ray fluorescence spectroscopy (XRF), is a technique for qualitatively or quantitatively determining elemental composition by measurement of the wavelength and intensities of the electron transitions from the outer to the inner energy levels of the atom. The energy associated with these transitions (—0.6-60 keV) is significantly greater than that associated with the transitions in optical atomic spectroscopy (approximately a few electron volts). The emitted x-ray spectrum does not depend on the way in which the atomic excitation is produced, but in XRF, a beam of energetic x-rays is used. 

Electron probe microanalysis (EPMA), X-ray analysis (energy dispersive, EDX, or wavelength dispersive, WDX), and X-ray fluorescence spectroscopy (XRF) are... 

One method for determining glass composition and glass colorant content is x-ray fluorescence spectroscopy (XRF). This method can be utilized to determine glass colorant content with a high degree of accuracy. However, this analysis method may not always be the most desirable in a production environment due to the cost of equipment, and the delay in acquisition of results that can accompany sample preparation and analysis. 

X-ray fluorescence spectroscopy (XRF) is a technique for the determination of elemental composition of materials, for elements greater than atomic number 11, present above 0.05% concentration [27-29]. The technique is similar to the EPMA, and x-ray analysis in the electron microscope (Section 2.6.1), except that the EPMA is used for local analysis whereas XRF is a bulk technique. Exposure of the sample to an x-ray beam causes electrons to be ejected and outer shell electrons to fall into the vacancies, emitting x-rays of discrete energy. Characteristic energies are associated with specific elements and the x-ray intensities are related to the concentration of the element in the sample. There are problems with this direct association of x-ray intensity and concentration, due to absorption by the matrix but standards and software programs are available to calculate elemental composition. XRF experiments have the advantage of being rapid and nondestructive. These techniques are usefully applied to the assessment of fillers, additives and contaminants in polymers, and software is available for quantitation. 

The concentration of inorganic components in forage crops varies according to crop maturity, temperature, and soil pH and composition. The analyses of mineral content can reveal soil or management deficiencies as well as optimum harvest time for proper crop management. Actual mineral analyses are used to determine the amount of mineral supplementation to be added to an animal ration for proper nutritional balance. Reference methods of analysis include inductively coupled argon plasma (ICP), atomic absorption spectroscopy (AAS), and x-ray fluorescence spectroscopy (XRF). These techniques are well established for the analysis of mineral elements in whole-plant material. The exact procedures for sample preparation and analysis are well documented. Copies of the procedures may be obtained from instrument manufacturers or are readily found using basic texts for each analytical technique. 

X-Ray fluorescence spectroscopy (XRF) is another commonly used method for the analysis of additives in pol3rmers. As the technique is not suitable for use with elements of lower atomic number than fluorine, primary antioxidants which contain either oxygen or nitrogen as the active element cannot be analyzed by XRF. Secondary antioxidants, however, which contain either phosphorus or sulfur as the active element, can be readily analyzed by this method. 

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