Bulk analysis methods

Independent of depth profiling considerations, SNMS provides a powerful bulk analysis method that is sensitive and accurate for all elements, from major to trace element levels. Since SNMS is universally sensitive, it offers obvious advantages over elementally selective optical methods. 

Thermal analysis techniques (DSC,TGA, DMTA...) operating on mini or micro samples can detect pinpoint heterogeneities in final parts that bulk analysis methods such as rheom-etry are unable to do. Transient variations of moulding parameters, local design mistakes, internal stresses that influence the properties of the final product, notably impact behaviour, dimensional stability, warpage. .. can be displayed. 

Modern bulk analysis methods make possible non-destructive chemical identification, which means that the sample remains intact after the analysis. Such a procedure is provided by electron microprobe or X-ray fluorescence analyses, in which the sample is irradiated by electron beams or X-rays and the elemental composition is determined on the basis of induced characteristic X-ray emissions. These methods have been successfully employed to study both stratospheric (Junge, 1963) and tropospheric (Gillette and Blifford, 1971) aerosol particles. Neutron activation analysis is also widely used to identify the chemical composition of atmospheric particulate matter (e.g. Duceef ai, 1966 Rahn etal., 1971) this is also a non-destructive procedure. 

D Johnson, et al. A chemical element comparison of individual particle analysis and bulk analysis methods. Scanning Electron Microsc 1 469, 1981. 

For highly dispersed metals on high surface-area supports, EXAFS, which is a bulk analysis method, actually monitors phenomena at the catalyst surface. EXAFS is also a very powerful method for investigating promoter-support interactions (cf. Sharpe et al. [561). 

X-Ray Fluorescence analysis (XRF) is a well-established instrumental technique for quantitative analysis of the composition of solids. It is basically a bulk evaluation method, its analytical depth being determined by the penetration depth of the impinging X-ray radiation and the escape depth of the characteristic fluorescence quanta. Sensitivities in the ppma range are obtained, and the analysis of the emitted radiation is mosdy performed using crystal spectrometers, i.e., by wavelength-dispersive spectroscopy. XRF is applied to a wide range of materials, among them metals, alloys, minerals, and ceramics. 

Although XRF is generally the X-ray spectrometry method of choice for analysis of major and trace elements in bulk specimens, useful PIXE measurements can be made. A detailed review of the main considerations for thick-target PEXE provides guidance for trace analysis with known and unknown matrices and bulk analysis when the constituents are unknown. Campbell and Cookson also discuss the increased importance of secondary fluorescence and geometrical accuracy for bulk measurements. 

Because of the complex nature of the discharge conditions, GD-OES is a comparative analytical method and standard reference materials must be used to establish a unique relationship between the measured line intensities and the elemental concentration. In quantitative bulk analysis, which has been developed to very high standards, calibration is performed with a set of calibration samples of composition similar to the unknown samples. Normally, a major element is used as reference and the internal standard method is applied. This approach is not generally applicable in depth-profile analysis, because the different layers encountered in a depth profile of ten comprise widely different types of material which means that a common reference element is not available. 

Table 8 shows results obtained from the application of various bulk and surface analysis methods to lithium metal at rest or after cyclization experiments, as well as at inert and carbon electrodes after cathodic polarization. The analytical methods include elemental analysis, X-ray photoelectron spectroscopy (XPS or ESCA), energy-dispersive analysis of X-rays (X-ray mi-... 

Conventional bulk measurements of adsorption are performed by determining the amount of gas adsorbed at equilibrium as a function of pressure, at a constant temperature [23-25], These bulk adsorption isotherms are commonly analyzed using a kinetic theory for multilayer adsorption developed in 1938 by Brunauer, Emmett and Teller (the BET Theory) [23]. BET adsorption isotherms are a common material science technique for surface area analysis of porous solids, and also permit calculation of adsorption energy and fractional surface coverage. While more advanced analysis methods, such as Density Functional Theory, have been developed in recent years, BET remains a mainstay of material science, and is the recommended method for the experimental measurement of pore surface area. This is largely due to the clear physical meaning of its principal assumptions, and its ability to handle the primary effects of adsorbate-adsorbate and adsorbate-substrate interactions. 

The choice of method for a particular application should take into account this categorisation, as well as the precision and accuracy required. This chapter mainly deals with bulk analysis and speciation. 

GDS instruments are viable alternatives to the traditional arc and spark-source spectroscopies for bulk metals analysis. Advantages of GDS over surface analysis methods such as AES, XPS and SIMS are that an ultrahigh vacuum is not needed and the sputtering rate is relatively high. In surface analysis, GD-OES, AES, XPS and SIMS will remain complementary techniques. GD-OES analysis is faster than AES (typically 10 s vs. 15 min). GD-OES is also 100 times more sensitive than... 

The complex flow pattern on the shell-side, and the great number of variables involved, make it difficult to predict the shell-side coefficient and pressure drop with complete assurance. In methods used for the design of exchangers prior to about 1960 no attempt was made to account for the leakage and bypass streams. Correlations were based on the total stream flow, and empirical methods were used to account for the performance of real exchangers compared with that for cross flow over ideal tube banks. Typical of these bulk-flow methods are those of Kern (1950) and Donohue (1955). Reliable predictions can only be achieved by comprehensive analysis of the contribution to heat transfer and pressure drop made by the individual streams shown in Figure 12.26. Tinker (1951, 1958) published the first detailed stream-analysis method for predicting shell-side heat-transfer coefficients and pressure drop, and the methods subsequently developed... 

The analysis methods are national in scope and address emissions from a wide variety of industrial and community source types. The materials reviewed are of widely disparate natures. They include metals, and bulk and trace hydrocarbons, including chlorinated and oxide derivatives of hydrocarbons. The analyses are intended to be preliminary screening analyses for use in scoping and prioritizing regulatory attention to toxic exposures from the chemicals studied. 

Recently, methods for quantitatively determining the chemical element composition of solid materials by x-ray emission spectroscopy using the electron microprobe have become available. A significant advantage of the electron microprobe, compared with methods for bulk analysis. Is Its capability for rapid analysis of many different mlcron-slze areas of a solid sample. Thus, In a relatively short time, we can obtain several hundred quantitative analyses of the chemical element content of a solid sample. These analyses usually will be different because sample homogeneity Is absent on the micron level. Thus, each chemical analysis Is a linear sum of the chemical elements In the subset of minerals present at that location. Generally, we expect the number of minerals present In a mlcron-slze spot to be less than the total number of minerals In the bulk sample. 

Cluster analysis Is used to determine the particle types that occur in an aerosol. These types are used to classify the particles in samples collected from various locations and sampling periods. The results of the sample classifications, together with meteorological data and bulk analytical data from methods such as instrunental neutron activation analysis (INAA). are used to study emission patterns and to screen samples for further study. The classification results are used in factor analysis to characterize spatial and temporal structure and to aid in source attribution. The classification results are also used in mass balance comparisons between ASEM and bulk chemical analyses. Such comparisons allow the combined use of the detailed characterizations of the individual-particle analyses and the trace-element capability of bulk analytical methods. 

Now NIST, National Institute of Science and Technology. fThe bulk analysis is by standard wet chemical methods. The glassy phase was analysed by analytical transmission electron microscopy. Adapted from Qian Glasser (1988) and Qian et al. (1988). 

The time required to conduct an interfacial tension experiment depends largely on the properties of the surfactants and less on the chosen measurement method. A notable exception is the drop volume technique, which, due to the measurement principle, requires substantial ly more time than the drop shape analysis method. Regardless of the method used, 1 day or more may be required to accurately determine, e.g., the adsorption isotherm (unit D3.s) of a protein. This is because, at low protein concentrations, it can take several hours to reach full equilibrium between proteins in the bulk phase and those at the surface due to structural rearrangement processes. This is especially important for static interfacial tension measurements (see Basic Protocol 1 and Alternate Protocols 1 and 2). If the interfacial tension is measured before the exchange of molecules... 

One of the potentially more productive avenues of research using LA-ICP-MS involves the characterization of paints and glazes used in the decoration of pottery. Just as bulk analysis of clays by INAA, XRF, ICP-MS, and other analytical methods have demonstrated to be a productive avenue of research for making interpretations regarding past cultural systems, chemical characterization... 

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