Volatile solvent

Volatility is one of the most important properties of a hydrocarbon solvent. Volatility has a direct relation to the time it takes to evaporate the solvent and, therefore, to the drying time for the dissolved product. The desired value of volatility varies greatly with the nature of the dissolved product and its application temperature. Therefore, whether it be an ink that needs to dry at ambient temperature, sometimes very fast, or whether it be an extraction solvent, the volatility needs are not the same. 

The molecular weight and density of the solvent influence the volume of the evaporated sample and hence the pressure wave. Solvent volatility nay Influence the distribution of sample between the vapor and droplet phases. The same sample amount dissolved in different solvents may produce different peak areas. 

Sample preparation for the common desorption/ionisation (DI) methods varies greatly. Films of solid inorganic or organic samples may be analysed with DI mass spectrometry, but sample preparation as a solution for LSIMS and FAB is far more common. The sample molecules are dissolved in a low-vapour-pressure liquid solvent - usually glycerol or nitrobenzyl alcohol. Other solvents have also been used for more specialised applications. Key requirements for the solvent matrix are sample solubility, low solvent volatility and muted acid - base or redox reactivity. In FAB and LSIMS, the special art of sample preparation in the selection of a solvent matrix, and then manipulation of the mass spectral data afterwards to minimise its contribution, still predominates. Incident particles in FAB and LSIMS are generated in filament ionisation sources or plasma discharge sources. 

Identification/quantification of residual monomers/solvents/volatile additives... 

Sufficient solvent volatility for removal from the product by evaporation or distillation. 

Semisolid samples. As with liquid samples, methods (B) and (C) are the best choices for this type of sample. The specific choice will depend on fhe rheological properties (viscosity, density, air retention) of the particular preparation. These samples are best measured in the transflectance mode. Liquid and semisolid samples may contain a mixture of solvents of disparate volatility which may evaporate separately during the measurement process. Differences in solvent volatility can alter the sample matrix and lead to errors in the determination which are best avoided by using a set of calibration samples spanning an expanded range of solvent proportions. ... 

This technology can treat materials contaminated with a wide range of organic contaminants, including solvents, volatile organic compounds (VOCs), and semivolatile organic compounds (SVOCs). CFBC is particularly suited for the treatment of media contaminated with polychlorinated biphenyls (PCBs). 

A. Polveri alia sola nitrocellulosa a solvente volatile o Polveri a una base (Single Base Propellants with Volatile Solvent). To these belong a proplnt listed by Giorgio, p 205 as Polvere italiana per cartucce cal 8 per mitragliatrice, which contd NC (12.8% N) 97, Centralite 2... 

Consider when solvent cannot be removed by evaporation (either temperature sensitivity or low solvent volatility). 

Next let us consider those difficulties associated with the determination of the amount of material deposited on the surface. We have already noted that the method of depositing insoluble monolayers by spreading permits the accurate determination of n. Since the spreading technique requires solvent volatility, care must be exercised to prevent the stock solutions from changing concentration due to evaporation prior to their application to the surface. Also, precise microvolumetric methods must be used to dispense the solution on the aqueous surface since the quantity used is small. The solvent (as well as the solute) must be free from contaminants. There is also the possibility that the solvent will extract spreadable contaminants from the waxed surfaces of the float, barriers, and tray. Some workers advocate addition and evaporation of one drop at a time to minimize this. Oily contaminants may also reach the water surface from the fingers and from the atmosphere. These last sources are particularly hard to control Tests for reproducibility and blank compressions (i.e., moving the barrier toward the float on a clean surface) are the best evidence of their absence. 

Solentte. See under Pclvcri a dcppia base con solvente volatile Solfite - Vol 3, p C440-L Stahilite - Vol 2, p B118-L Super BM. per galleria. See under BM esplosivi... 

As one would expect, there is a strong correlation between solubility in non-polar solvents, volatility and molecular complexity of metal amide compounds. The degree of association can typically be related to empirical formula (ML ), metal covalent radius and the steric demand of the amide substituents. 

Subsequent studies by physicochemical methods — and initialy the structure studies — have shown that the majority of the derivatives of this class are molecular compounds, many of them being soluble in nonpolar solvents, volatile, their structures belonging to the same types as those of the homometallic ones described in Chapter 4. 

Table II. Operating Conditions for Separation of n-Paraffins from C16-C32 Wax Distillate With Supercritical Solvent Volatility Application and 5A Molecular Sieves...

Solvents are selected such that some will escape relatively quickly from paint films to prevent excessive flow, while others will escape slowly to provide film leveling and adhesion. With typical alkyd coatings, the first 30% of solvent has been observed to evaporate as quickly as the neat solvents, essentially at a constant rate which is dependent on volatility. Later stage evaporation occurred several times more slowly and was rate-controlled by solvent diffusion to the surface of the paint film. The transition point between this behavior was defined as the resin solids content at which the evaporation rate due to volatility equaled that due to diffusion. Transition points have been observed to typically occur at a resin solids content of 40-50% v/v. Thus alkyd paints, normally formulated at 27-40% v/v resin solids, generally exhibit rapid initial solvent-release driven by volatility while high solids coatings (usually 65-75% v/v resin solids) dry solely by a diffusion-controlled process with negligible influence by solvent volatility (Ellis, 1983). 

This occurs by an instability of one of the free interfaces the polymer-polymer interface, the film surface, or a combination of the two, each of which gives rise to a distinct lateral length scale. Which of the two capillary instabilities is selected is a complex issue. It depends on various parameters, such as polymer-polymer and polymer-solvent compatibility, solvent volatility, substrate properties, etc. in a way which is not understood. Despite this lack of knowledge, playing with these parameters permits the selection of one of the two distinct length scales associated with these two mechanisms, or a combination thereof. 

In order to move from one Elemental level to another, it is necessary to have the Proper Medium. To turn Earth into Fire you must pass through Water and Air. One Element is the conductor of the others adjacent, and that one Element dissolves and subtilizes the other. Thus one Element is the other s magnet, solvent, volatilizing, condensing, coagulating and fixing principles. 

Hadj Romdhane, I. Danner, R. P., "Solvent Volatilities from Polymer Solutions by Gas-Liquid Chromatography," J. Chem. Eng. Data, 36, 15 (1990). 

---