Elemental analysis volumetric

PP bead foams were subjected to oblique impacts, in which the material was compressed and sheared. This strain combination could occur when a cycle helmet hit a road surface. The results were compared with simple shear tests at low strain rates and to uniaxial compressive tests at impact strain rates. The observed shear hardening was greatest when there was no imposed density increase and practically zero when the angle of impact was less than 15 degrees. The shear hardening appeared to be a unique function of the main tensile extension ratio and was a polymer contribution, whereas the volumetric hardening was due to the isothermal compression of the cell gas. Foam material models for finite element analysis needed to be reformulated to consider the physics of the hardening mechanisms, so their predictions were reliable for foam impacts in which shear occurred. 16 refs. 

Well-defined heterobimetallic complexes were isolated from Ln(Oz -Pr)3/ Et2AlCl/Et3Al and Ln(Oz -Pr)2Cl/Et3Al mixtures and characterized by means of elemental analysis, IR spectroscopy, and gas-volumetric analysis. The formation of complexes of general formula (z-PrO)2HLn2Cl3HAlEt2 (Ln = Gd, Dy, Er, Tm) with a two double bridged structure was considered, how-... 

A standard wet chemical analysis (ASTM D-811) is available for determination of aluminum, barium, calcium, magnesium, potassium, silicon, sodium, tin, and zinc. The procedure involves a series of chemical separations with specific elemental analysis performed by using appropriate gravimetric or volumetric analyses. 

Traditional methods of elemental analysis depend on specific chemical reactions for given elements, either in solution using titrations (known as volumetric analysis) or precipitation of solids that can be weighed (gravimetric analysis). Although such methods are still used for specific and very accurate purposes, they have been replaced in routine work by automated instrumental methods. Combustion analysis is used to determine C, H, N, and sometimes S, by complete oxidation of the compound forming C02, H20, N2 and S02. The gases are separated and determined automatically... 

Elemental analysis for total sulfur is performed, often together with C, H, N, in a flowing stream of oxygen, air or other oxidizing gases in combustion tubes, in a number of variants (some of them automated), for macro and micro applications. The volatile products formed may then be used after absorption for volumetric, gravimetric, titri-metric and colorimetric quantification (e.g., Nebesar 1971/72, Kirsten 1979, MAEE 1986,... 

Arc and spark source spectroscopies were ihc first instrumental methods to become widely used lor analysis. These techniques, which began to replace the chis-sical gravimetric and volumetric methods for elemental analysis in the 1920s, were based on excitation of emission spectra of elements with electric arcs or high-voltage sparks. These spectra permitted the qualitative... 

As already discussed, the size, the shape and the dispersion are characteristic parameters of metal particles and will determine their properties. It is possible to characterize them as follows (i) The size of the metal particles (transmission electron microscopy, (TEM) [79-81], extended X-ray absorption fine structure (EXAFS) [82, 83]), (ii) their structures (X-ray diffraction (XRD), TEM), (iii) their chemical composition (TEM-EDX, elemental analysis), (iv) the chemical state of the surface and bulk metal atoms (X-ray photoelectron spectroscopy (XPS)), Mossbauer [84], thermo-programmed-reduction (TPR)), (v) chemisorption capacity toward probe molecules such as H2, O2, NO and CO (volumetric or dynamic measurements) [85-90]. 

The analytical techniques used for single element analysis can be divided into three groups. The first group consists of titration techniques using various means to detect the end point of titration, such as volumetric titration, fluorophotometric titration, potentiometric titration, and spectrophotometric titration. The second group includes direct detection techniques such as direct ternary inclusion compound fluorescent spectrophotometry and the use of ISEs. The third group is that of separation methods such as IC and HPLC, which are used in complicated sample matrices to reduce the sample matrix interference. 

Parallel method comparisons are used to establish the validity of a new method developed for five organic pharmaceutical compovmds, food colors, and color additives. The standard methods such as the Japanese Standard Food Additives and Japanese Standard of Cosmetic Ingredients method, based on volumetric and gravimetric titration, have been used to establish new methods developed for the determination of I, Cl, Br, and SO4 in food colors. The results obtained indicate good agreement in both accuracy and precision for procedures based on the oxygen flask method as compared with the standard methods. In addition to anion elemental analysis, method validation has also been carried out for metal analysis such as that of Ce(III), Th(IV), and U(VI), with the results showing acceptable limits of variation. 

The first quantitative analytical fields to be developed were for quantitative elemental analysis, which revealed how much of each element was present in a sample. These early techniques were not instrumental methods, for the most part, but relied on chemical reactions, physical separations, and weighing of products (gravimetry), titrations (titrimetry or volumetric analysis), or production of colored products with visual estimation of the amount of color produced (colorimetry). Using these methods, it was found, for example, that dry sodium chloride, NaCl, always contained 39.33% Na and 60.67% Cl. The atomic theory was founded on early quantitative results such as this, as were the concept of valence and the determination of atomic weights. Today, quantitative inorganic elemental analysis is performed by atomic absorption spectrometry (AAS), AES of many sorts, inorganic MS (snch as ICP-MS), XRF, ion chromatography (1C), and other techniques discussed in detail in later chapters. 

The oxygen-cobalt ratio was checked not only by direct elemental analysis, but also by gas-volumetric measurements of oxygen absorbed. 

National Institute of Standards and Technology (NIST). The NIST is the source of many of the standards used in chemical and physical analyses in the United States and throughout the world. The standards prepared and distributed by the NIST are used to caUbrate measurement systems and to provide a central basis for uniformity and accuracy of measurement. At present, over 1200 Standard Reference Materials (SRMs) are available and are described by the NIST (15). Included are many steels, nonferrous alloys, high purity metals, primary standards for use in volumetric analysis, microchemical standards, clinical laboratory standards, biological material certified for trace elements, environmental standards, trace element standards, ion-activity standards (for pH and ion-selective electrodes), freezing and melting point standards, colorimetry standards, optical standards, radioactivity standards, particle-size standards, and density standards. Certificates are issued with the standard reference materials showing values for the parameters that have been determined. 

Volumetric methods of analysis of rare earth elements. 

Some qualitative analytical reagents for the detection of rare earths elements are given in Tables 1.26 and 1.27. Gravimetric, volumetric, complexometric, precipitation and polarographic methods of analysis of rare earths are summarized in Tables 1.28 to 1.32. 

The major elements of marine sediments are still determined by classical gravimetric and volumetric methods. Atomic absorption spectrometric methods have been applied to sediment analysis, although emission spectrometry, X-ray fluorescence spectrometry and neutron activation analysis... 

Dry ashing involves heating the sample in air in a muffle furnace at 400-800 °C to destroy the sampfe matrix, e.g. soil. After decomposition, the sample residue is dissolved in acid and quantitatively transferred to a volumetric flask prior to analysis. The method may lead to the loss of volatile elements, e.g. Hg, As. 

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