Electron probe X-ray

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 ... 

The electron probe X-ray microanalyzer provides extraordinary power for measuring the elemental composition of solid matter with pm lateral spatial resolution. The spatial resolution, limited by the spread of the beam within the specimen, permits pg samples to be measured selectively, with elemental coverage from boron to the actinides. By incorporating the imaging capability of the SEM, the electron probe X-ray microanalyzer combines morphological and compositional information. 

Pitman, M.G., Lauchli, A. Stelzer (1981). Ion distribution in roots of barley seedlings as measured by electron probe X-ray micro-analysis. Plant Physiology, 66, 673-9. 

I. Bondarenko, H. Van Malderen, B. Treiger, P. Van Espen and R. Van Grieken, Hierarchical cluster analysis with stopping rules built on Akaike s information criterion for aerosol particle classification based on electron probe X-ray microanalysis. Chemom. Intell. Lab. Syst., 22 (1994) 87-95. 

W. Van Borm, Source Apportionment of Atmospheric Particles by Electron Probe X-ray Microanalysis and Receptor Models. Doctoral Thesis, University of Antwerp, 1989. 

Diffuse reflectance infrared Fourier transform spectroscopy deuterium triglycine sulphate energy compensated atom probe energy dispersive analysis energy-loss near edge structure electron probe X-ray microanalysis elastic recoil detection analysis (see also FreS) electron spectroscopy for chemical analysis extended energy-loss fine structure field emission gun focused ion beam field ion microscope... 

The primary methods of analyzing for lead in environmental samples are AAS, GFAAS, ASV, ICP/AES, and XRFS (Lima et al. 1995). Less commonly employed techniques include ICP/MS, gas chromato-graphy/photoionization detector (GC/PID), IDMS, DPASV, electron probe X-ray microanalysis (EPXMA), and laser microprobe mass analysis (LAMMA). The use of ICP/MS will become more routine in the future because of the sensitivity and specificity of the technique. ICP/MS is generally 3 orders of magnitude more sensitive than ICP/AES (Al-Rashdan et al. 1991). Chromatography (GC,... 

With some exceptions (2-4), there have been relatively few recent reviews of microanalysis that have considered applications to plant science. In a previous review of this topic (5), I concentrated almost entirely on methods of specimen preparation for electron probe X-ray microanalysis. Here I highlight further developments in this area, and also broaden the scope of the review to include other microanalytical techniques. This chapter introduces the main types of hardware that are now available for microanalysis, reviews the main techniques used to prepare plant material prior to analysis, and provides protocols for the two major techniques. 

There is little doubt that cryotechniques, and particularly cryo-SEM, are now the dominant methods of specimen preparation for electron probe X-ray microanalysis when localization of soluble ions is required. In a previous review (5) these techniques were covered in considerable detail and this material is not reiterated here. Instead, protocols for the two major methods are provided and some recent developments and publications in this area are highlighted. 

Nishihara, T. Kondo, M. Nonaka, T. Higashi, Y. Location of calcium and phosphorus in ashed spores of Bacillus megaterium determined electron probe X-ray microanalysis. Microbiol. Immunol. 1982, 26, 167-172. 

X-ray microanalysis techniques— in particular, electron probe x-ray microanalysis (EPXMA or EPMA) and SEM coupled with energy dispersive spectrometers (EDS, EDX) are, by far, one of the surface analysis techniques most extensively used in the field of art and art conservation, and they have actually become routine methods of analyzing art and archaeological objects and monitoring conservation treatments [34, 61, 63]. 

Routine inorganic elemental analysis is carried out nowadays mainly by atomic spectrometric techniques based on the measurement of the energy of photons. The most frequently used photons for analytical atomic spectrometry extend from the ultraviolet (UV 190-390 nm) to the visible (Vis 390-750 nm) regions. Here the analyte must be in the form of atoms in the gas phase so that the photons interact easily with valence electrons. It is worth noting that techniques based on the measurement of X-rays emitted after excitation of the sample with X-rays i.e. X-ray fluorescence, XRF) or with energetic electrons (electron-probe X-ray micro-analysis, EPXMA) yield elemental information directly from solid samples, but they will not be explained here instead, they will be briefly treated in Section 1.5. 

High-resolution compositional measurements are possible through use of a variety of microanalytical methods. Ideally, these should be non-destructive, can be targeted on small areas of sample, and have low minimum detection limits. Electron-probe X-ray microanalysis (EPXMA) and proton-induced X-ray emission (PIXE) techniques have both been used successfully on archaeological sediment thin sections (19, 20). Both techniques yield elemental composition data for a range of elements. EPXMA has the advantage of being nondestructive, whereas PIXE when used on thin-section samples is typically destructive conversely the detection limit for PIXE is lower than EPXMA. 

Electron probe X-ray micro analysis measurements The distribution of molybdenum element on the used catalyst was measured by JCXA-733, at probe current 3.60x10 A, accelerated volt 25KV and beam diameter 10 tun. 

Freudenrich CC, Hockett D, Ingram P, LeFurgey A. In situ cryofixation of kidney for electron probe X-ray microanalysis. J. Struct. Biol. 1994 112 173-182. 

The particles were deposited on the slides by in5>actation, sedimentation and diffusion. Subsequently, the samples were analyzed by scanning electron microscopy (SEM). Information on morphology and size distribution was obtained from image analysis, while the elemental composition of particles was determined by electron probe X-ray microanalysis (EPXMA). 

T7. Tousimis, A. J., and Adler, I., Electron-probe X-ray microanalyser study of copper within Descemet s membrane of Wilson s disease. J. Histochem. Cytochem, 11, 40-47 (1963). 

In general, the stores are loaded with Ca + buffered with millimolar concentrations of EGTA (Endo et al., 1977 Saida and Nonomura, 1978 Itoh et al., 1982a,b Saida, 1982). The stores are fully loaded within 3 to 5 min at 1 (jlM Ca2+ (Saida, 1982), whereby the Ca2+ uptake depends on the Ca + concentration (Saida, 1982 Yamamoto and van Breemen, 1986). At Ca + concentrations greater than 1 jlM, a Ca +-induced Ca release was observed (Itoh et al., 1981 Saida, 1982). The deposition of Ca2+ in the SR of saponin-permeabilized smooth muscle was demonstrated by electron probe X-ray microanalysis (Kowasaki et al.,... 

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