Composition quantitation

As pointed out above, accumulatory pressure and weight loss measurements usually refer to the total reaction. When there are several volatile products, it is necessary to identify all components and investigate progressive changes in gas composition. Quantitative determinations of the amounts of each product (EGA) should, ideally, be combined with measurements of the total extent of reaction, although Gam [143] has recommended caution in the interpretation of results from simultaneous measurements. 

Zhou et al. (2005) determined anethole composition quantitatively by GC in the fruit of I. verum from various places in the Guangxi province. The average recovery rate and the RSD were 102.31 and 1.78%, respectively. The content of anethole in the fruit of I. verum from various places was more than 4.5%. 

The elemental composition is useful for characterisation of inorganic pigments and organic dyes. However, a database is needed for their identification. In all ballpoint pen inks, sulfur, copper, silicon and phosphorus are present in the elemental composition. Some samples also contain zinc, chlorine, bromine and calcium. In black inks, chromium and lead are additionally found. Samples differ with respect to the elemental composition quantitatively rather than the qualitatively. A greater variability in elemental content is observed for gel inks. 

It takes two independent variables to uniquely define a two-phase system having a fixed overall composition. Quantitative determination of the other variables requires thermodynamic data, such as enthalpy and component equilibrium distribution coefficients, or X-values. Distribution coefficients are defined as... 

TS-IIC represents the material retained in a hot (350-400°C) catch tank and is believed to be indicative of the amount of material which is not volatilized during reaction. Extensive experimentation with hydropyrolysis has shown that actual coke production of much less than 1% is achieved. Details of minor coke buildup over extended runs have not yet been determined. The optimum conditions to obtain the desired yields and to prevent extraordinary coke formation will depend upon the feedstock properties and composition. Quantitative relationships between feedstock composition and optimum process conditions have not yet been conducted. 

Molecular composition (quantitative, qualitative) Depth Lateral Other Not used for spatially resolved analaysis. ... 

Munl] Isothermal aimealing, microprobe for phase compositions, quantitative optical microscopy for phase amoxmts 1200 to 1350°C, a + 7 two-phase field... 

A versatile, simple and inexpensive method has been recently proposed for the synthesis of sequence-controlled multiblock copolymers by one-pot polymerisation at ambient temperature. Aciylic block copolymerisation under UV irradiation 360 nm) was obtained in the absence of conventional photoredox catalysts and dye-sensitizers, by means of low concentrations of CuBra in synergy with MCe-Tren [MCe-Tren Tren = tris(2-aminoethyl)amine]. The potential of the method was demonstrated by alternating four different aciylate monomers in various combinations within the polymer composition. Quantitative conversion and narrow dispersity were achieved. " The procedure is versatile, as demonstrated by polymerisation of a number of (meth)aciylate monomers, including poly(ethylene glycol) methyl ether aciylate (PEGA480), te/t-butyl aciylate, methyl methaciylate, and styrene. Moreover, hydrojyl- and vic-diol-functional initiators are tolerated, forming a,co-heterofunctional poly(aciylates). Notably, temporal control is... 

Diene conjugates Ketodienes Phospholipids Qualitative composition Quantitative composition Sterols... 

AES Thickness of thin films and elemental composition (quantitative AES) Galiy etal. (1998) ... 

Fatty acids in castor oil have been determined in a like fashion [426]. They were reacted with radioactive diazomethane. The methyl esters of the ordinary fatty acids were separated from those of the monohydroxy- and dihydroxy acids, using adsorption TLC. AU three classes of methyl ester were eluted and the ratio of the amounts determined by measuring their radiation intensities. The mixture of esters of non-hydroxy-acids was then fractionated further by reversed phase PC and its composition quantitatively determined in the gas flow proportional counter. The ratio of monohydroxy- to dihydroxy- fatty acids may be more easily determined through the hot acetylated acids or esters. The small amount of dihydroxy fatty acids could then be labelled with two radioactive acetyl groups per molecule, which would double the specific activity and increase the accuracy of the result still further. 

There are a few approaches to fadUtate the interpretation of data on the complex and variable mixtures of chlorobiphenlys in marine environmental samples. The composition of mixtures can be represented as mole percent contributions of individual CBs to their sum Duinker et al., 1980) or as molar ratios, e.g., CBx/CB153 Boon et al., 1992). This allows visual, qualitative and quantitative comparisons between samples with widely different overall compositions. Quantitative and less arbitrary comparison is possible with statistical methods such as principal component analysis Jackson, 1991). Finally, distribution patterns between the CB mixtures in solution and in suspended particles can be studied by plotting concentration ratios in these compartments Le., distribution coefficients) against known molecular properties, e.g., octanol-water distribution coefficients Schulz-BuU et al., 1998). 

To explain the temperature dependence of the moduli, Gibson et al have considered that the crystalline sequences linking two or more crystal blocks act like short fibres in an aligned short fibre composite. Quantitative predictions of the temperature dependence of the axial modulus were obtained, which were in good agree.-nent with experimental data. In physical terms, the a - relaxation is considered to be a crystalline slip process and the 3 relaxation relates primarily to mobility of the non-crystalline regions. 

Langhorst, S.E., O Donnell, J.N., and Skrtic, D. (2009) In vitro remineralization of enamel by polymeric amorphous calcium phosphate composite quantitative microradiographic study. Dent Mater, 25 (7), 884-891. 

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