Spectrograph x-ray fluorescence

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. 

Highly sensitive iastmmental techniques, such as x-ray fluorescence, atomic absorption spectrometry, and iaductively coupled plasma optical emission spectrometry, have wide appHcation for the analysis of silver ia a multitude of materials. In order to minimize the effects of various matrices ia which silver may exist, samples are treated with perchloric or nitric acid. Direct-aspiration atomic absorption (25) and iaductively coupled plasma (26) have silver detection limits of 10 and 7 l-lg/L, respectively. The use of a graphic furnace ia an atomic absorption spectrograph lowers the silver detection limit to 0.2 l-ig/L. 

Ultimately, all quantitative analytical methods rely upon standards, whose composition is determined by the classical techniques of wet chemical quantitative analysis. Obviously, the preferred techniques for analyzing art objects are nondestructive, such as x-ray fluorescence, neutron activation, electron microprobe (both dispersive and nondispersive techniques), and so forth. Emission spectrographic analysis is not suit-... 

Despite the availability of neutron activation, X-ray fluorescence and spectrographic multielement methods, atomic absorption continues to be very important. It has advantages of versatility and ease of calibration for laboratories with single element or variable analytical requirements. The high capital cost of the equipment makes the other methods competitive only for multielement, multisample programs. 

The total iron content may be determined directly in the soil by the X-ray fluorescence analysis or by a spectrographic method. In the case of classic methods, the soil sample should be first decomposed either by melting with Na2C03 or by the action of hydrofluoric acid. The melting procedure is more advantageous, since in this case further elements can also be determined simultaneously with iron. When it is only necessary to determine iron, it is advantageous to use the decomposition with hydrofluoric acid, which does not need the separation of silicic acid. In solution, iron is determined most frequently by the photometry, AAS or polarography. ... 

This is very much a specialised method, but is very useful for the identification of small inclusions in solids. The basic instrument is an electron microscope, but all or part of the electron beam can be focused onto any desired part of the sample causing it to emit X-rays characteristic of that material. These are then collimated and analysed in a conventional X-ray fluorescence spectrograph, thus giving at least a partial ratio analysis of that part of the sample. These instruments are expensive and are not for routine analysis, but are very useful for the identification of small problem areas in solid materials. 

Emission spectrographic or X-ray fluorescence analysis of ethanol-insolubles or of ash i.e., residue at 600-C) This indicates which inorganic compounds are present. 

Halothane in 1 to 2 g. tissue samples was determined by x-ray spectrographic (fluorescence) analysis for bromine in 10 ml. hexane extracts (81). 

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]. 

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