Elemental analysis gravimetric

Analysis. Excellent reviews of phosphate analysis are available (28). SoHds characterization methods such as x-ray powder diffraction (xrd) and thermal gravimetric analysis (tga) are used for the identification of individual crystalline phosphates, either alone or in mixtures. These techniques, along with elemental analysis and phosphate species deterrnination, are used to identify unknown phosphates and their mixtures. Particle size analysis, surface area, microscopy, and other standard soHds characterizations are useful in relating soHds properties to performance. SoHd-state nmr is used with increasing frequency. 

ADMET polymers are easily characterized using common analysis techniques, including nuclear magnetic resonance ( H and 13C NMR), infrared (IR) spectra, elemental analysis, gel permeation chromatography (GPC), vapor pressure osmometry (VPO), membrane osmometry (MO), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). The preparation of poly(l-octenylene) (10) via the metathesis of 1,9-decadiene (9) is an excellent model polymerization to study ADMET, since the monomer is readily available and the polymer is well known.21 The NMR characterization data (Fig. 8.9) for the hydrogenated versions of poly(l-octenylene) illustrate the clean and selective nature of ADMET. 

The aryl-substituted derivatives of [Bi(SeC6H2R3-2,4,6)3] (R = Me, Pr, Bu) are the only isolated examples of selenolate complexes. They have been characterized by mp, elemental analysis, NMR spectroscopy, and thermal gravimetric analysis, and the solid-state structure of the isopropyl-substituted derivative reveals a tricoordinate environment for bismuth [Bi-Se 2.630(8)-2.711(8) A Se-Bi-Se 92.3(2)-103.3(2)°], imposed by the steric bulk of the ligands (38). 

The crystals of halcinonide are not solvated with water, based on a total volatile content of 0.3% obtained by thermal gravimetric analysis, a correct elemental analysis, and a loss-on-drying value of 0.6% (of. section 4.1, Elemental and Inorganic Analyses). 

Basic magnesium phosphates may be characterized by x-ray and thermo-gravimetric analyses and elemental analysis. Magnesium may be determined... 

Gravimetric Analysis, Inorgonic. That branch of quantitative chemical analysis.in which a desired constituent is converted (usually by precipitation) to a pure compd or element of definite, known compn, and is weighed. In a few cases, a compd or element is formed which does not contain the constituent but bears a definite mathematical relationship to it. In either case, the amount of the desired constituent can be detd from the weight and compn of the precipitate. Methods exist for the detn of all the elements by gravimetric analysis... 

Procedures. A standard recipe for the latex preparation is shown below (St + M2) 20 g, (water + buffer) 160 g, and initiator 5 mmole/1. The weight fraction of M2 in monomer charge (f) was varied from 0.01 to 0.50. Polymerizations were carried out at 55°C or 70°C and pH 2.5 or 9.0 under nitrogen. Samples were withdrawn from the reaction mixture at various time intervals and the polymer was precipitated in an excess of acetone. The conversion and polymer composition were determined by gravimetric means and by elemental analysis, respectively. The M2 fraction in instantaneously-formed copolymer ( Fi ) was calculated from eq. 1 ... 

Gravimetric and elemental analysis lead to the following bruto-formula for the products of fullerene chlorination C6oCln (n=2 8). The broad bands in IR spectra (Fig. 2) close to characteristic vibrations for C-Cl bonds (frequencies 885, 850 and 808 cm"1) evidenced the presence of the mixture different isomers in the sample... 

Also, the conversion degree may be calculated from the kinetic data determined by the gravimetric method or from the data of elemental analysis during the surface reaction... 

When the product is purified, its identity is established by H NMR, IR, FAB-MS, etc. An elemental analysis associated with a fusion point determination by thermo-gravimetric methods helps to establish the identity of the substance and its stoichiometry. Then the product is analysed on various GC and HPLC phases with various detectors. Impurities are often present in amounts that do not allow H NMR identification. 

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. 

The methods used can be conveniently arranged into a number of categories (a) fractionation by precipitation (b) fractionation by distillation (c) separation by chromatographic techniques (d) chemical analysis by spectrophotometric techniques (infrared, ultraviolet, nuclear magnetic resource. X-ray fluorescence, emission, neutron activation), titrimetric and gravimetric techniques, and elemental analysis and (e) molecular weight analysis by mass spectrometry, vapor pressure osmometry, and size exclusion chromatography. 

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... 

The analysis of separately synthesized single substances is much simpler than that of compound mixtures. Here, the yield and purity can be determined in the traditional way purification by extraction, crystallization, or chromatography, gravimetric determination of the yield, and confirmation of the purity by elemental analysis, chromatography, or NMR. 

Vol. 1C, Classical Analysis Gravimetric and Titrimetric Determination of the Elements, New York Elsevier, 1962. 

At one time GC analysis was less accurate than classical elemental analysis, but the development of simple, reliable and sensitive thermal conductivity detectors (TCDs), special electronic integrators and small computers has brought the reproducibility of chromatographic peak-area measurements to at least 0.2% (see, for example, ref. 11) the accuracy of chromatographic elemental analysis is now close to that of standard gravimetric methods, which is normally 0.3% [12]. If the GC elemental analysis is used for the determination of reactive compounds, such as halogens or hydrogen halides, use is made of gas density balances in which the sensitive elements are protected by a flow of an inert gas [13]. 

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,... 

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