Solubility ratio

In solving problems of this type, it is convenient to list the material balance and the solubility ratios. The various points on the material balance are calculated by multiplying the quantity of the component which does not precipitate from solution during the transition from one point to another (normally the... 

Nad in cooling or the KCl in the evaporative step) by the solubility ratio at the next step, illustrated as follows ... 

Solution component KCl Nad Water Solubility ratios KCl NaCl Water ... 

ILs, on the other hand, are uniquely suited for use as solvents for gas separations. Since they are non-volatile, they cannot evaporate to cause contamination of the gas stream. This is important when selective solvents are used in conventional absorbers, or when they are used in supported liquid membranes. For conventional absorbers, the ability to separate one gas from another depends entirely on the relative solubilities (ratio of Henry s law constants) of the gases. In addition, ILs are particularly promising for supported liquid membranes, because they have the potential to be incredibly stable. Supported liquid membranes that incorporate conventional liquids eventually deteriorate because the liquid slowly evaporates. Moreover, this finite evaporation rate limits how thin one can make the membrane. This... 

Figure 13 Plot of log of fugacity ratio or solubility ratio for methylprednisolone polymorphs as a function of solvent and reciprocal absolute temperature. (Reprinted with permission from Ref. 47.)...

The solubilities in water and octanol of the pyrazino[l,2-A]quinazolones 23 (R1 =Me, R4 = H R1 = R4 = Me) with various N-2 substituents were determined. Solubility ratios and partition coefficient values were fitted to a predictive equation to evaluate the possibility of aqueous solubility estimates <1997IJP233>. 

Fig. 18 Solubilities at 20°C of the two polymorphs of cimetidine, form A (<9>-) and form B (0), as a function of the mole fraction of 2-propanol in the 2-propanol/water system. Also shown are the solubility ratios (form A/form B) calculated at each solvent composition. (The data are adapted from Ref. 128.)...

The availability of contaminating organic compounds is also often described by their partition coefficient between water and a solvent, most often octanol. The more soluble a compound is in water, the more available for decomposition. By describing the solubility ratio, the relative rates of organic compound decomposition in soil can be estimated [3],... 

GETTING STARTED SOLUBILITY AND THE DOSE SOLUBILITY RATIO... 

Figure 1 Using the dose solubility ratio and solubility as a guide to assessing the level of formulation challenge.

A reactor charged with 4,4 -diphenylether-dicarboxylic acid, hydrazinesulfate, and polyphosphoric acid were mixed and reacted for 1 hour at 160°C and then further heated to 180°C. This mixture was then treated with 4-aminobenzenesulfonic acid and heated for an additional 2 hours. The molar solubility ratio of polyphosphoric acid/hydrazinesulfate and the molar monomer ratio ofhydrazinesulfatc/4,4 -dipheny-lether-dicarboxylic acid were kept constant at 10 and 1.2, respectively. The mixture was further treated with sufficient 4-aminobenzenesulfonic acid so that the molar ratio of in situ formed polyhydrazide was maintained at 1 1. After heating was stopped, the mixture was poured into warm water containing 5 wt% sodium hydroxide solution and a dark blue fiber obtained. The fiber was washed in distilled water and then dried in a vacuum furnace for 48 hours at 100°C. The dried material had a nitrogen/carbon ratio of 0.174 and a sulfur/carbon ratio of 0.058. The product had an Mw of... 

Rinaki E, Valsami G, Macheras P. Quantitative biophannaceutics classification system the central role of dose/solubility ratio. Pharm Res 2003 20(12) 1917-1925. 

As is to be expected with modifications showing tire mutual relationship described, the less stable form is more soluble in ordinary solvents above 95-5° C., therefore, the octahedral form is the more soluble, whilst below this temperature prismatic sulphur possesses the greater solubility. At the ordinary temperature the solubility ratio for most solvents is approximately 1-8 1. 

Solubility ratio s (dimensionless) The ratio of the equilibrium liquid concentration to the ozone concentration in the gas (function of 7) I - ll... 

The concept of equilibrium distribution is another area where names can cause much confusion. The equilibrium distribution of a compound between the gas and liquid phase has been expressed in various forms, i. e. Bunsen coefficientfi, solubility ratio s, Henry s Law constant expressed dimensionless Hc, or with dimensions H. These are summarized in along with equations showing the relationships between them. Another more general term to describe the equilibrium concentrations between two phases is the partition coefficient, denoted by K. It is often used to describe the partitioning of a compound between two liquid phases. 

Not only have various names been used for the same concept, Morris (1988) found a variety of values for the equilibrium concentration of ozone in water reported in the literature. Based on the data from more than nine authors, he suggested that a linear correlation between the solubility ratio of ozone,, 5 (which is the inverse of the dimensionless Henry s Law constant Hc), and the temperature can be used as a first estimate for the solubility of ozone in water ... 

Equilibrium properties also seem to show both types of anomalies illustrated in Figures 10A and 10E. As an example, we have discussed (31) the study by Klots and Benson (91) of the solubility ratio of nitrogen to argon. A solubility relation of the type shown in Figure 10A is observed in this case while other solubility data more frequently show the behavior indicated in Figure 10E. 

As indicated by equation 35, the vapor pressure—solubility ratio (eq. 34), only provides accurate results when (/) reliable vapor pressure and aqueous solubility data are employed, (2) the quantity x is small enough to be neglected, and (3) Henry s law applies for the dissolved substance in water up to the saturation limit. If water miscibility in the organic is expected to be significant, equation 35 is much preferred, assuming miscibility data are available (42). This correction can amount to several percent even when the aqueous solubility is low. For example, water solubility in /2-octanol is about 5% whereas the -octanol solubility in water is in the parts per thousand range. 

The magnitudes of the solubility of forms I and II of this drug varied signiLcantly in water, decyl alcohol, and dodecyl alcohol. However, their data showed that the solubility ratio was independent of solvent, but dependent on temperature. Figure 19.3 shows the data for these polymorphs in water The difference in slopes (indicating a difference in enthalpies of fusion) for the two polymorphs can be used to calculate a transition temperature, where both forms have the same physical stability The identity of the metastable form and the degree of solubility enhancement both depend on the temperature chosen for comparison. 

This constancy of solubility ratio between solvents for two polymorphs at a given temperature does not apply to solvated/nonsolvated pairs, where additional terms arising from the release of the solvate complicate the calculations. 

Behme and Brooke (1991) have derived an equation for estimating the solubility ratio of two polymorphs at a given temperature using DSC data on the enthalpy of fiMty) nd the melting temperature of each form. The free energy of the transition orthe natural logarithm of the solubility ratio multiplied byRT (Equation 19.6) was estimated by the difference between the solubility estimates for each form calculated by Equation 19.10 ... 

Pudipeddi and Serajuddin (2005) recently compiled 81 solubility ratios for 55 different drugs. Their results, which parallel those presented here, show most of the solubility ratios were between 1 and 2 (84%), however, 9% of them had ratios greaterthan 3. Although the relative increase in... 

Drug Solvent/Temperature Polymorphs and Solubilities Ratio Reference... 

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