Solvent content

Other Propellants. Dimethyl ether (DME) [115-10-6] is finding use as an aerosol propeUant. DME is soluble in water, as shown in Table 5. Although this solubiHty reduces DME s vapor pressure in aqueous systems, the total aerosol solvent content may be lowered by using DME as a propeUant. The chief disadvantage is that DME is flammable and must be handled with caution. 

Health and Safety Factors. The Material Safety Data Sheets provided by the suppUers should be consulted for each product. In general, products are aqueous emulsions with low levels of toxicity. Products with high solvent content have mostly been eliminated. Personnel handling the chemicals should always avoid contact of the products with skin and eyes, and avoid exposure to vapors if the product contains volatile components. 

Decaffeination Regulations. Eor decaffeinated roasted coffee, EEC standards indicate the maximum content of caffeine as 0.1% db for decaffeinated instant coffee it is 0.3% db. In the United States, decaffeination usually signifies that 97% of the caffeine has been removed. Permissible solvents for decaffeination processes are defined by national legislation, eg, EDA or EEC directive. The maximum residual solvent content after decaffeination, roasting, or instant coffee processing is to be kept within good manufacturing practice, ie, very low ppm levels or below at point of sale (46). 

A slight variation of the above method accounts for increases in the solvent content of the gas stream between the inlet and the outlet of the tower and assumes that the evaporation of solvent tends to cool the hquid. This procedure offsets a part of the temperature rise that... 

The filtered dough is then returned to a mixer and the alcohol content reduced to 25% by kneading under vacuum. Further reduction in the alcohol content is brought about by rolling the compound on a hooded two-roll mill. The milled product is then consolidated on a two-bowl calender and sheeted off in hides about j in thick. At this stage the solvent content is between 12 and 16%. 

Compounding may be carried out by either a wet or a dry process. In the wet process, now obsolescent, the ingredients are mixed as a viscous solution in acetone in a dough mixer. The resulting dough is then rolled on a hot two-roll mill to evaporate the bulk of the solvent. It is then necessary to season the resulting hides until the solvent content is reduced to a tolerably low level. 

Process validation should be extended to those steps determined to be critical to the quality and purity of the enantiopure drug. Establishing impurity profiles is an important aspect of process validation. One should consider chemical purity, enantiomeric excess by quantitative assays for impurity profiles, physical characteristics such as particle size, polymorphic forms, moisture and solvent content, and homogeneity. In principle, the SMB process validation should provide conclusive evidence that the levels of contaminants (chemical impurities, enantioenrichment of unwanted enantiomer) is reduced as processing proceeds during the purification process. 

J mol ). This is additional evidence in favor of rate limitation by inner diffusion. However, the same reaction in the presence of Dowex-50, which has a more open three-dimensional network, gave an activation energy of 44800 J mol , and closely similar values were obtained for the hydrolysis of ethyl acetate [29] and dimethyl seb-acate [30]. The activation energy for the hydrolysis of ethyl acetate on a macroreticular sulphonated cationic exchanger [93] is 3566 J mol . For the hydrolysis of ethyl formate in a binary system, the isocomposition activation energy (Ec) [28,92] tends to decrease as the solvent content increases, while for solutions of the same dielectric constant, the iso-dielectric activation energy (Ed) increases as the dielectric constant of the solvent increases (Table 6). 

Their disadvantages, particularly in comparison with coal tar epoxies, include the fact that they are limited in film thickness per coat and therefore require multi-coated application. They have a higher solvent content and therefore there is an increasing risk of solvent entrapment, and the slower cure may limit their use in a tidal zone. The best use is for immersed conditions. 

Naphthalenedisulfonate-acetonitrile as the only mobile phase with a silica column coated with a crosslinked aminofluorocarbon polymer has proven to be an effective combination for the separation of aliphatic anionic surfactants. Indirect conductivity and photometric detection modes are used to monitor these analytes. The retention of these surfactants is found to depend on both the ionic strength and the organic solvent content of the mobile phase. The mechanism of retention is considered to be a combination of both reverse phase and ion exchange processes. Selective separation of both alkanesulfonates and... 

Modern lacquers with a low organic solvent content are widely formulated as stable lattices. Such a modified latex is useful as a coating for substrates such as paper, wood, and metals, and as a binder in aqueous systems. 

As illustrated in the previous sections, the electrochemical properties of conducting polymer films are strongly influenced by polymer-ion interactions. These interactions are in turn influenced by the nature of the solvent and the solvent content of the film. Consequently, the electrochemical behavior of conducting polymer films can be highly solvent dependent. Films can even become electrochemically inactive because of lack of solvation.114,197... 

In situ gravimetry on polyaniline has revealed a complicated dependence of solvent content and transport of the solvent (aqueous or nonaqueous) on pH.187 Two to three water molecules per electron can be inserted during oxidation in strongly acid solutions, while in propylene carbonate, less than one solvent molecule is involved. Propylene carbonate is first ejected from the film during oxidation, then inserted, and finally ejected again in the final stages. 

Fig. 7. A typical X-ray diffraction pattern of the Fepr protein fromZJ. vulgaris (Hil-denborough). The pattern was recorded on station 9.6 at the Synchrotron Radiation Source at the CCLRC Daresbury Laboratory using a wavelength 0.87 A and a MAR-Research image-plate detector system with a crystal-to-detector distance of 220 nun. X-ray data clearly extend to a resolution of 1.5 A, or even higher. The crystal system is orthorhombic, spacegroup P2i2i2i with unit cell dimensions, a = 63.87, b = 65.01, c = 153.49 A. The unit cell contains four molecules of 60 kDa moleculEu- weight with a corresponding solvent content of approximately 48%.

The physical characteristics should be considered (in combination as appropriate) in relation to the proposed dosage form and route of administration. Factors to be considered extend to solubility characteristics, crystal form and properties, moisture or solvent content, particle size and size distribution (which may affect bioavailability, content uniformity, suspension properties, stability, and preclinical or clinical acceptability), polymorphism, etc. 

Liquid coating materials with low organic solvent content should be used to minimize the amount of volatile organic compounds that will be volatized and to reduce the volume of solid and liquid hazardous waste created. 

The adsorption of block and random copolymers of styrene and methyl methacrylate on to silica from their solutions in carbon tetrachloride/n-heptane, and the resulting dispersion stability, has been investigated. Theta-conditions for the homopolymers and analogous critical non-solvent volume fractions for random copolymers were determined by cloud-point titration. The adsorption of block copolymers varied steadily with the non-solvent content, whilst that of the random copolymers became progressively more dependent on solvent quality only as theta-conditions and phase separation were approached. 

In the absence of polymer the sediment volume of silica depends on the non-solvent fraction of the medium as shown in Figure 6. The sediment volume assessment of steric stabilization behavior of the copolymers is illustrated in Figures 7a to 7c. At low styrene contents, both the random and block copolymers show a steady increase in sediment volume as the non-solvent content is raised up to the phase separation value. With polystyrene and random copolymers of high styrene content, the sediment volume stays largely constant with alteration in the non-solvent fraction until the theta-point is approached and then continues to become larger as the limit of solubility is reached. In Figure 7b only the data points of RC 86 are shown, RC 94 giving almost identical values. 

Block copolymers at high styrene contents behave similarly, with no break around the micellar region. Two of the block copolymers are shown separately in Figure 7c. The low M.W. BC 90 moves from an apparently adequate stabilization in CCI4 to a new level of modest protection at higher CyH g volume fractions. The block polymer of 42% styrene gives a hint of a discontinuity at the non-solvent content for micelle formation, but thereafter stabilizes the silica until the conditions approach those for phase separation. 

Figure 7. Sediment volumes of silica 186 in solutions of polymers at various non-solvent contents. Plateau adsorption, (a) curve 1, RC 08 2, RC 86 3, PS III. (b) curve 1, BC 10 ...

Figure 11. log(coagulation rate/min l) of silica 186 in solutions of polymers at various non-solvent contents. 

In this IR sampling technique, a thermogravimetric (TG) analyzer is interfaced to an IR spectrophotometer so that the evolved gas from the sample/TG furnace is directed to an IR gas cell. This IR sampling technique lends itself to the identification and quantitation of residual solvent content for a pharmaceutical solid [17], and also to the investigation of pharmaceutical pseudopolymorphs. 

System B is the most widely used for CL detection after an HPLC separation. In this system, two pumps are required for delivering the reagent solutions in the following cases (1) the solutions for CL reaction are first combined and then mixed with an eluent (2) CL reaction conditions (e.g., pH, water and organic solvent contents, and salt concentration) need to be optimized before mixing with the CL reagent. 

Structure determinations of several Fe(II) compounds of 2-triazolyl-l,10-phenanthroline and its methyl-substituted derivatives proved that in addition to the two nitrogen donor atoms of the 1,10-phenanthroline entity, the N-4 of the 1,2,4-triazole ring participates in coordination, even when a methyl substituent occupies the position adjacent to this donor atom [15, 16]. All compounds obtained exhibit Fe(II) spin crossover behaviour, its extent depending on the nature of the anionic groups and the solvent content. 

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