Energy dispersive X-ray fluorescence ED-XRF

Other analytical techniques have less frequently been used nuclear magnetic resonance spectroscopy (NMR) (e.g., tocopherols in toothpaste by hyphenated LC-NMR), energy dispersive X-ray fluorescence (ED-XRF) (e.g., heavy metals determination), surface enhanced Raman scattering (e.g., determination of 4-aminobenzoic acid or PABA, in sunscreens), neutron activation analysis (e.g., determination of iron and zinc), and thermometric analysis (e.g., fluoride in toothpaste). 

Although the principles and mechanism of excitation for energy dispersive X-ray fluorescence (ED-XRF) are exactly the same as for wavelength dispersive (WD)-XRF, the analytical characteristics of ED-XRF instrumentation demonstrate some significant... 

XRF is closely related to the EPMA, energy-dispersive X-Ray Spectroscopy (EDS), and total reflection X-Ray Fluorescence (TRXF), which are described elsewhere in this encyclopedia. Brief comparisons between XRF and each of these three techniques are given below. 

This non-destructive technique is a very suitable tool for rapid in-line analysis of inorganic additives in food products (Price and Major, 1990 Anon, 1995). It can be readily used by non-skilled operators, and dry materials can be pressed into a pellet or simply poured into a sample cup. The principles of this technique related to food analysis are described by Pomeranz and Meloan (1994). A useful Internet site is http //www.xraysite.com, which includes information about different XRF instruments from various companies. Wavelength dispersive X-ray fluorescence (WD-XRF) or bench-top energy dispersive (ED-XRF) instruments are available. XRF is a comparative technique, thus a calibration curve needs to be established using food products of the same type as those to be... 

In order to individually analyze the fluorescent X-rays from each element, the spectral separation of the X-rays is required. There are two types of spectrographic methods for XRF. They are wavelength dispersive X-ray spectrometry (WDS, WDX) and energy dispersive X-ray spectrometry (EDS, EDX). The characteristics of WDS and EDS are shown in Table 1. Please refer to the following reference for more detailed explanations of XRF [1]. 

Energy-Dispersive X-Ray Spectroscopy, EDS, is a specific technique for the detection and energy distribution determination of X-Ray Fluorescence, XRR XRF is the phenomena where X rays are emitted from a material when bombarded by high energy radiation (electrons, ions, X rays, neutrons, gamma rays). Some of the X-ray energies emitted are characteristic of the atoms present, allowing atomic identification in the material of interest. 

Major elements Scanning Electron Microscopy/Energy Dispersive X-Ray (SEM/EDS) analysis (Camscan 4DV/Tracor TN 5500) (7) X-ray Fluorescence (XRF) analysis, melting technique (Siemens SRS 300). 

X-ray fluorescence (XRF). The sample is irradiated with monochromatic X-rays that eject electrons from the inner shells of the elements. When an electron from an outer shell of the ion drops into the vacancy, it emits characteristic X-rays whose wavelength is used to identify the element and whose intensity is related to the amount present. XRF is used primarily for elements heavier than magnesium because of the weak fluorescence of lighter elements and absorption of the X-rays within the particles. The combination of transmission or scanning electron microscopy (TEM/SEM) with X-ray fluorescence, also known as energy-dispersive spectrometry (EDS), was discussed in Section B.2b. 

XRF/EDS X-Ray Fluorescence/Energy Dispersive Speclroscopy Thin liims, single layer Prim. X-ray beam X = 0.02-0.1 nm 12-80 keV Fluorescent X-rays 1-100 pm 10 mm Eiemenlai anaiysis aii eiemenis except H, He, Li - (EDS aiso used in XRD, SEM, TEM and EPMA) 26,26... 

XRF-ED X-ray fluorescence analysis using energy dispersive detection. 

The composition of a specimen is often determined by X-ray fluorescence (XRF) spectrometry, which performs rapid, qualitative, and semiquantitative determination of major and minor surface elements. Although both wavelength- and energy-dispersive (ED) analyzers can be used to detect the secondary X-rays, ED-XRE instruments are more common for the compositional determination of archaeological and conservation samples. Detection limits of 0.1% are expected therefore, the analysis is difficult for trace elements. A laboratory XRE system, commonly used to quantify elements in metal and ceramic samples (noninsulating materials need to be coated), is considered to be an indispensable tool. As with all these surface analytical techniques, care has to be taken that weathering products (thick patinas or corrosion crusts) do not obscure bulk analysis results. Thus, samples are normally prepared to provide a flat polished surface to produce quantitative results. 

Abbreviations AES, Auger emission spectrometry CRM, Certified reference material DL, Detection limit ED, Energy dispersive ESRF, European Synchrotron Radiation Facility EXAES, Extended X-ray absorption fine structure NEXAFS, Near edge X-ray absorption fine structure PCI, Phase contrast imaging RM, Reference material SR, Synchrotron radiation SRM, Standard reference material TXRF, Total reflection X-ray fluorescence XANES, X-ray absorption near edge structure XAS, X-ray absorption spectrometry XDM, X-ray diffraction microscopy XFCT, X-ray fluorescence computerized microtomography XPEEM, X-ray photoelectron microscopy XPS, X-ray photoelectron spectrometry XRD, X-ray diffraction XRF, X-ray fluorescence... 

In order to find out the phase composition of fine laterite ore reduced with reduction temperature of 1375°C, the atomic ratio of C/O of 1.2, and the percentage of CaO of 12%, the samples were examined by X-Ray fluorescence(XRF), X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS). The chemical compositions of the fine ore by reduction-magnetic separation was shown in Table 3.1, the XRD pattern of fine ore by reduction-magnetic separation was seen in Fig.3.5, and the SEM pattern of fine ore by reduction-magnetic separation was shown in Fig.3.6 and the chemical compositions of observed district in SEM pattern was shown in Table 3.2. 

Notes TIMS, thermal ionization mass spectrometry ICP-MS, inductively coupled plasma mass spectrometry GD-MS, glow discharge mass spectrometry XRF, x-ray fluorescence XRD, x-ray diffraction GC-MS, gas chromatography-mass spectrometry SEM, scanning electron microscope TEM, transmission electron microscope SIMS, secondary ion mass spectrometry EDS, energy-dispersive sensor WDS, wavelength-dispersive sensor. 

Besides XRD, other important studies are elemental analysis, either by chemical or physical methods, such as neutron activation analysis (NAA), x-ray fluorescence (XRF), or x-ray energy dispersive spectroscopy (X-EDS), for example (see Sections 7.6.1, 7.3.3, and 7.5.2, respectively) the advantage of these methods is that they are non destructive, as oppossed to wet chemical analysis. Additionally, IR spectroscopy can bring useful complementary information. Sometimes, the chemical composition is required along XRD analysis to fully identify a mineral. Also, thermal analysis (Section 7.6.5) is a useful tool in the qualitative and, sometimes, quantitative determination of clay minerals. 

Qualitative analysis is, in principle, very simple with XRF and is based on the accurate measurement of the energy, or wavelength, of the fluorescent lines observed. Since many WD-XRF spectrometers operate sequentially, a 20 scan needs to be performed. The identification of trace constituents in a sample can sometimes be complicated by the presence of higher order reflections or satellite lines from major elements. With energy-dispersive XRF, the entire X-ray spectrum is acquired simultaneously. The identification of the peaks, however, is rendered difficult by the comparatively low resolution of the ED detector. In qualitative analysis programs, the process is simplified by overplotting so called KLM markers onto... 

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