Solvents retention

With just a few exceptions, there is a dearth of published information providing systematic studies of retention volumes as a function of composition of the eluent over the whole composition range of binary solvents. To rectify this situation, a general equation for HPLC binary solvent retention behavior has been proposed [59] that should help generate a chromatographic retention model to fit Eq. (15.20) ... 

Possible determinations from DSC or DTA measurements include (1) heat of transition, (2) heat of reaction, (3) sample purity, (4) phase diagram, (5) specific heat, (6) sample identification, (7) percentage incorporation of a substance, (8) reaction rate, (9) rate of crystallization or melting, (10) solvent retention, and (11) activation energy. Thus, thermo-calorimetric analysis can be a useful tool in describing the chemical and physical relationship of a polymer with respect to temperature. 

The injection of a solvent into the gas chromatograph makes it difficult to identify and quantify the compounds which are eluted close to the solvent retention time. In addition to that, impurities of the solvent may interfere with the sample compounds and therefore make the quantification more error-prone. 

Newman, D.J. and Nunn, C.J. (1975) Solvent retention in organic coatings. Progress in Organic Coatings, 3, 221-43. 

Regardless of classification, polysaccharides express varying degrees of ethanol tolerance neutral species are mostly unresponsive to electrolytes, including weak acid, and protonated species precipitate with low solvent retention from strong acid and Ca2+ solutions. Exceptions to many general rules abound for example, polyacids are generally the most stable species,... 

The material balances, which now account for over 100% of most of the samples (Table II), reflect the difficulty in removing the last portion of the solvent from the insoluble fraction. As the insoluble fraction increases, the error attributable to solvent retention becomes more apparent. 

CVD eliminates the problems of solution based synthesis techifiques such as solvent retention and contamination. Retention of volatile solvents subsequent to film formation can cause out gassing resulting in formation of pinholes, voids etc. Also, substituent groups used to provide solubility frequently result in degradation of the material properties of the host polymer. These problems are absent in CVD. Further, the dry nature of CVD results in high... 

The solvent retention of the drained material is a bit of a misnomer, and it would be more accurately defined as the weak miscella retention. The weak mis-cella retained in the drained material contains approximately 1 % oil. In the meal desolventizer, the solvent is evaporated leaving behind the traces of oil, often referred to as the residual oil. In order to minimize the residual oil left in meal, it is important to minimize the amount of weak miscella carried forward to the meal desolventizer. 

A significant solvent effect was observed. The reaction of 4-acetylphenyl triflate with PhCH(Me)SiF3 (38% ee, 5) at 60 °C resulted in retention (31% ee, S) in THF, but inversion (8% ee, R) in HMPA-THF (1 20). In DMF-THF (1 10) or DMSO-THF (1 10) retention (16% S in both cases) was still observed, but at a low level. Thus, in a nonpolar solvent, retention of configuration resulted, whereas in a polar solvent system the reaction proceeded by inversion [30]. 

Co-solvent Retention-Release. Our results indicate that co-solvents can be retained in complex substrates, possibly by absorption into intraparticle liquids. 

In addition to these specifications, the downstream operations of filtration, washing, and drying require a filterable crystal with low solvent retention in order to facilitate drying at low temperature. 

Begin with a mass balance. Assume that all of the solvent retained by the paper pulp is done so in the first contact stage and, further, that no separation occurs in this stage, only mixing and solvent retention. 

DJ Johnson, DAC Compton. Solvent retention studies for pharmaceutical samples using an integrated TGA/FT-IR system. Spectroscopy 3 47-50, 1988. 

Maximum solution viscosity is obtained using Super VM P naphtha whereas minimum solution viscosity results from methanol, hexane blends, i.e., blends of the two non-solvents reduce viscosity to a greater degree than the use of a single true solvent. It was also observed, in studying the drying rate of the resin, that slow dry is related to the solvent retentive nature of the polymer. Non-solvents are not retained by the polymer. 

Figure 12. Solvent retention of various solvents in a vinyl resin film.

Fig. 2. Effect of solvent retention on the softening temperature of ethyleellulose films plasticized by 17% (A), 33% ( ) and 50% (O) of propylene glycol [26]...

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