Bulk elemental analyses

The condition in Equation 3 is a potential source of error for thin-film analyses in mineralogy because the abundance of low-Z elements (e.g. F, O, N, H) is usually calculated from stoichiometry or inferred from bulk elemental analyses. However, comparisons within a suite of minerals will remain internally consistent, provided assumptions about low-Z elements are appropriately included in data reduction. 

We have been investigating the nature of these novel solids in order to ascertain information which may lead to new catalytic applications. Two important questions to be addressed are (i) what are the local T-atom (tetrahedral atom) arrangements (silicon, aluminum, and phosphorus), and (ii) what is the elemental homogeneity Questions (i) has been addressed mainly through the use of solid-state NMR while the answer to question (ii) is most appropriately obtained from surface to bulk elemental analyses. 

During the tests, fuel and bed material samples were collected. These samples were mainly investigated with SEM-EDS, Bulk elemental analyses were also carried out. The unproblematic behaviour of the bed material was confirmed and no agglomerate formation was observed except in the close proximity of occasional quartz centres that were unintentionally present in bed. It was observed that the majority of the bed particles were coated with several thin superimposed layers. The composition of each layer was different. The outermost coating layer contains a significant amount of magnesium. It may be this outermost layer that hinders the agglomeration of the particles in this new bed. 

Al, S, and Cl. Similarly, bulk elemental analyses cannot readily distinguish among oxidation states (e.g., Fe and Mn +, Mn + and Mn " ") nor among polymorphs (i.e, minerals, such as calcite, aragonite, monohydrocalcite, vaterite, that have different structures and genetic relationships within a lacustrine system but share the same elemental stoichiometry). 

Complete qualitative and quantitative bulk elemental analysis of conducting solids to ultratrace levels... 

Table 1 shows (C/N). The CMK-3 samples r (XPS) than in bulk (elemental analysis) milar, except for the OCM-.N2.00 sample. 

XPS spectra were collected for the same petroleum residua and asphaltene samples used in the XANES studies described above. For all samples the total amount of sulfur relative to carbon as measured by XPS was comparable to that determined by bulk elemental analysis. The spectra were deconvoluted by curve fitting, and the approximate quantifications thus derived are shown in Table 111. 

Particle composition is far more difficult to evaluate. Bulk elemental analysis [atomic absorption spectroscopy (AA) or inductively coupled plasma mass spectrometry (ICP-MS) are most common for metals] is useful in confirming the overall bimetallic composition of the sample, but provides no information regarding individual particles. Microscopy techniques, particularly Energy Dispersive Spectroscopy (EDS), has supported the assertion that bimetallic DENs are bimetallic nanoparticles, rather than a physical mixture of monometallics [16]. Provided the particle density is low... 

All bulk elemental analysis methods, such as NAA and FAAS, suffer from the serious disadvantage of lack of specificity in that the elements detected are not unique to FDR but also occur from occupational and environmental sources. Many surveys were carried out to determine background levels of lead, antimony, and barium on the hands of people not involved with firearms. Some surveys also included copper and mercury. Both general and occupational data were gathered and threshold levels established for each of the elements. The threshold level may be defined as the level above which the results may be significant and correlate to the discharge of a firearm. The best that could be stated was that the levels detected were consistent with the discharge of a firearm but could not be taken as conclusive proof of the presence of FDR. 

Bulk elemental analysis methods have been employed by many workers to do quantitative studies of the amount of residue deposited on the firing hand. 

It is interesting to note that the automobile features often in the interpretation of FDR results. In the Price method231 the hands of suspects were examined for the presence of lead in particulate form. This method was discredited when it was discovered that automobile exhausts eject numerous lead particles into the environment from leaded petrol. When bulk elemental analysis methods were developed it was shown that lead could originate from leaded petrol and the car battery terminals. Antimony was also present in battery terminals and barium was present in motor oil. Finally, in the particle analysis method it has been claimed that lead, antimony, and barium unique FDR particles can originate from automobile brake linings.)... 

In the example above, the phases are such that the chemistry is unambiguous and the phase quantification could have been derived by normative calculation from bulk elemental analysis (XRF). This is not often the case, but it is frequently possible to establish the composition of each phase within a system via electron probe microanalysis or similar and conduct the inverse of a normative calculation to derive the bulk chemistry from the XRD QPA. This can then be compared with the results of a standards based technique such as XRF to obtain a measure of the accuracy of the XRD analysis. Examples of such calculations are given later in the sections dealing with application in mineralogical and industrial situations. Where this is not possible or practical, it is better to consider XRD QPA as a semi-quantitative technique at best. 

Mineralogical composition of ash samples and model systems was determined by XRD. X-ray fluorescence (XRF) analysis was also used for bulk elemental analysis of the ash. Raw coal analysis was performed by XRF and neutron activation (NAA). XRF elemental analyses of raw coal samples are listed in Table I. The neutron activation analyses were performed at North Carolina State University. 

Bulk elemental analysis of some catalysts was performed by atomic absorption. The results presented in table 1 show that coprecipitation method yields, within the experimental errors, catalysts with the Mo/Fe atomic ratio of preparation. Catalysts prepared by sol-gel method showed lower Mo/Fe atomic ratios than the expected value. Furthermore calcination of these catalysts under air flow enhances the loss of Mo. 

Bulk elemental analysis confirmed that the calcium form of self-bound LSX pellets has a Si/Al ratio of 0.99 and a calcium exchange capacity of 7.03 mequiv./g on a dry basis. The calcium... 

Amonette, J. E. R. W. Sanders, 1994. Nondestructive techniques for bulk elemental analysis. In Amonette, J. E. L. W. Zelanzny (eds.) Quantitative Methods in Soil Mineralogy. Soil Science Society of America, Inc., Madison, Wisconsin 1 8. 

In the past, a combination of several analysis techniques has often been applied to environmental aerosols because one technique can normally not give all requested answers. E.g. bulk elemental analysis by XRF or particle-induced X-ray emission (PIXE) or inductively-coupled mass or emission spectrometry (ICP-MS/ICP-OES) is often combined with ion chromatography (IC) to assess the soluble ions, gas chromatography mass spectrometry (GC-MS) for some organics, aethalometry for ambient soot determinations and gravimetry for aerosol mass per m. ... 

PreparationofRieke Nickel, Characterization of Active Nickel Powder, and Some Chemistry 257 Table 7.2 Bulk elemental analysis of active nickel powder. 

In samples 245-256, with narrow red and dark blue stripes, the Cu (red) and Co (blue) are rarely measurable, although the As, which is associated with Co, is often measurable at low levels. This shows that for this type of multi-coloured bead, bulk elemental analysis must be used in conjunction with visual inspection of beads and bead fiagments. 

Tucker et al demonstrated the applicability of LIBS to bulk elemental analysis of igneous rock powders. The LIBS spectra were modelled using PLS to predict major element compositions. Multiple calibration sets relevant to different rock types were preferred over a single all-encompassing calibration set. Baseline removal and transforming spectral data by their first derivative did not improve predictions and may even have negative effects. These results are directly applicable to spectra that will be acquired by the ChemCam experiment on Mars Science Laboratory, but also to terrestrial LIBS applications. 

ToF-SIMS is the most versatile of the surface analysis techniques that have been developed over the last 30 years. Analyses possible by SIMS include bulk elemental analysis in small volumes of material, in-depth analyses (depth profiles), imaging, analysis at interfaces, isotopic analysis and elemental and molecular surface analysis. 

Finally, surface cleanliness is critical to proper dispersion of micron particles in slurry vehicles and mixing and retention with bond components. The identity and concentration of surface impurities can be determined by surface spectroscopic and bulk elemental analysis techniques down to the part-per-million level. 

Perhaps the most common type of problem encountered in the analytical lab is a quantitative analysis. Examples of typical quantitative analyses include the elemental analysis of a newly synthesized compound, measuring the concentration of glucose in blood, or determining the difference between the bulk and surface concentrations of Cr in steel. Much of the analytical work in clinical, pharmaceutical, environmental, and industrial labs involves developing new methods for determining the concentration of targeted species in complex samples. Most of the examples in this text come from the area of quantitative analysis. 

In the analysis of trace elements or thin films on substrate using electrons, however, one finds that the MDL, may be increased by choosing Eq such that Uis just greater than 1. The reason for this is that the k factor, which is the ratio of the intensity from the sample to that from the standard, increases as Uapproaches 1 for thin films. Thus, by maximizing the k factor, the sensitivity is increased. For bulk sample analysis, however, the k factor will usually be a maximum ax. U- 2.5. 

The optimal analytical GDMS instrument for bulk trace element analysis is the one providing the largest analytical signal with the lowest background signal, the fewest problems with isobaric interferences in the mass spectrum (e.g., the interference of with Fe ), and the least contamination from instrument com-... 

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-... 

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