Quantitative X-ray microanalysis

All quantitative X-ray microanalysis requires that the background Bremsstrahlung be subtracted from the observed spectrum, so that the relative intensities of the characteristic X-rays can be determined. 

Hinde P, Richardson P, Koyro HW, Tomos AD. Quantitative x-ray microanalysis of solutes in individual plant cells a comparison of microdroplet and in situ frozen-hydrated data. J Microsc 1998 191 303-310. 

Lorimer, G. W. 1987. Quantitative X-Ray Microanalysis of Thin Specimens in the Transmission Electron Microscope A Review . Mineralogical Magazine 51 (359) 49-60. 

Electron Probe X-Ray Microanalysis (EPMA) is a spatially resolved, quantitative elemental analysis technique based on the generation of characteristic X rays by a focused beam of energetic electrons. EPMA is used to measure the concentrations of elements (beryllium to the actinides) at levels as low as 100 parts per million (ppm) and to determine lateral distributions by mapping. The modern EPMA instrument consists of several key components ... 

Scanning Electron Microscopy and X-Ray Microanalysis Principles of Electroanalytical Methods Potentiometry and Ion Selective Electrodes Polarography and Other Voltammetric Methods Radiochemical Methods Clinical Specimens Diagnostic Enzymology Quantitative Bioassay... 

It is therefore frequently difficult to find punctual areas in the sample having a sufficient concentration of the desired analyte to be detected by the x-ray microanalysis system. Thus, identification and eventually quantitation of metals in dec-orative/protective layers of pictorial samples by SEM/EDX frequently require an accurate and often time-consuming scanning process. 

This type of analysis would be helpful in the identification stage of the quantitative X-ray diffraction analysis method described in the previous section however, it appears that, by itself, X-ray microanalysis only of isolated particles will not... 

Analysis schemes developed for identifying clay minerals in the TEM based on EDS spectra (e.g., Murdoch et al.100) are inappropriate for colloidal samples dispersed on polycarbonate filters due to complications associated with the various sample-beam-substrate interactions that differ dramatically from that of ideal samples or standards with smooth polished surfaces.94 96 101 102 Correction procedures that account for the influence of particle size and morphology on x-ray spectra have been widely available for some time,101102 but these techniques have not been applied to the analysis of environmental particulates. To overcome the limitation of quantitative elemental analysis, some research groups have compared the x-ray spectra for sample colloids to the spectra for various minerals of similar size and composition under the same instrumental and sample preparation conditions to calibrate instrumental response.7 24 93 Noting the resolution problems associated with SEM analysis of submicron colloids, several research groups have chosen TEM as the primary discrete particle analysis technique,21 52 103 104 or have combined TEM analysis techniques, such as electron diffraction and x-ray microanalysis, to confirm conclusions drawn from SEM surveys.7,93 105... 

The potential uses of XRD powder diffraction in the study of clinker or anhydrous cement include the qualitative and quantitative (QXDA) determination of phase composition, and the determination of polymorphic modification, state of crystallinity and other features of individual phases. In principle, information on compositions of phases is obtainable through cell parameters, but, due to the lack of adequate reference data, XRD is generally less satisfactory for the clinker phases than X-ray microanalysis. Table 4.2 gives the pattern of a typical Portland cement, with indications of the assignments of peaks to phases. 

Thanks to the linear relationship between the intensity of the characteristic X-ray radiation generated in the sample by electrons and the concentration of the given element, quantitative elemental analysis is also possible. X-ray microanalysis performed using SEM-EDX is, in principle, point analysis and is suitable for studying very small samples of solid materials that are stable in an electron beam. The X-ray fluorescence method, on the other hand, can be applied to the study of both solids and liquids. The signal reaching the detector always originates from a certain sample volume, and thus it is not point analysis. It is more sensitive than the SEM-EDX method. 

In the most recent Pouchou and Pichoir model (PAP correction model) the authors aim to approximate the function integrable analytical form. This model is used not only to improve the quantitative performance levels of X-ray microanalysis but also to extend the scope of microanalysis in the study of stratified samples (determination of the thickness and composition of submicronic layers). The correction calculations are, in this case, conducted by iteration using the -ratios measured at various electron accelerating voltages (corresponding to different electron penetration depths). 

Fe2-xCrx(Mo04)3 provides a good opportunity for the quantitative, comparison of two analytical techniques - "classical" atomic absorption analysis and x-ray microanalysis. X-ray microanalysis of thin samples using scanning transmission electron microscopy has become an effective quantitative technique in the last few years(86). as opposed to the well-known electron microprobe analyses of bulk specimens(87) ... 

A combination of STEM and either energy dispersive X-ray microanalysis (see below) or electron energy loss can detect low elemental concentrations at the subcellular level. Leapman and Andrews (16) reported the ability to quantitate calcium in Purkinje cell dendrites to an accuracy of < 12 atoms. A low tempera-... 

Electron probe x-ray microanalysis (EPA) provides a means for obtaining quanlitative and quantitative elemental microanalysis within regions as small as a few cubic micrometers. 

X-Ray microanalysis can be used to quantitatively determine magnesium in microvolumes of biological fluids. The minimum detection limit is 0.05 mmol/liter for a 0.1 mL sample analyzed... 

Many interesting studies have been published on the effects of a polluted atmosphere on stone with emphasis on the more chemical aspects [39,40,41]. The physical-chemical analytical techniques employed in the study of building materials provide very accurate qualitative and quantitative results on the alterations related to the patina or crust as well as the bulk chemistry of the exposed stone. Scanning electron microscopy (SEM), Electron probe X-ray microanalysis (EPXMA), Fourier-transform infrared analysis (FTIR), X-Ray diffraction (XRD), energy dispersive X-Ray fluorescence, Ion Chromatography, are the most used techniques for the studies of sulphate black crusts as well as to evaluate the effect of exposition time of the sample stone to weathering[42,43]. 

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