Water-miscible cosolvents

The sample plate is prepared as in the preceding method. But before the spectra are taken, a volume Y of a water-miscible cosolvent is added to a volume Z of sample... 

Sugano et al. [562] also studied the effect of PEG400, DMSO, and ethanol, up to 30%, in their PAMPA assays. In general, water-miscible cosolvents are expected to... 

The charge-state section highlighted the value of Bjerrum plots, with applications to 6- and a 30-pKa molecules. Water-miscible cosolvents were used to identify acids and bases by the slope in the apparent pKa/wt% cosolvent plots. It was suggested that extrapolation of the apparent constants to 100% methanol could indicate the pKa values of amphiphilic molecules embedded in phospholipid bilayers, a way to estimate pAi m using the dielectric effect. 

Spurlock, F. C., and J. W. Biggar, Thermodynamics of organic chemical partition in soils. 3. Nonlinear partition from water-miscible cosolvent solutions , Environ. Sci. Technol., 28,1002-1009 (1994b). 

Similar to ink-jet inks, aqueous drawing and writing inks contain water miscible cosolvents as humectants or moisturizers (e.g., glycols, glycerin, or sorbitol), which stabilize the ink in the pen and at the nib. Typically, biocides and tensides are added to the ink formulation. 

Some waterborne epoxy systems may contain a proportion of water-miscible cosolvent to aid in film coalescence. Its presence may allow the formulator greater latitude to control properties such as stability, drying, and particularly rheology and still meet VOC levels required by pollution legislation. 

Small-volume injectable liquids are primarily aqueous solutions. However, because many important therapeutic agents are poorly soluble or totally insoluble in water, oily solvents and water-miscible cosolvents are used to produce ready-to-use solutions. 

Antimicrobial preservative disinfectant humectant plasticizer solvent stabilizer for vitamins water-miscible cosolvent. 

The behavior of aminoacylase both from porcine kidney and Aspergillus sp. towards a wide range of water-miscible cosolvents was investigated by Iborra et al.1661. They found that enzymatic activity can be correlated with the denaturing capacity of the water-cosolvent system. 

An example is the recovery and purification of amino acids via crystallization. Here, the solubility of the amino acid can be influenced by a number of methods (1) lowering the temperature, (2) evaporating the solvent, (3) selective removal of the solvent by means of membranes techniques, and (4) by using a water-miscible cosolvent such as lower alcohols and acetone. In the last of these, which is close to industrial practice, work is lost at a large number of places. Unequal quality of heat input (at a high T level) and recovery (at a low T level) and incomplete solvent recovery from the mother liquor increase lost work and, less obviously, incomplete recovery contributes to lost work as well. This is shown schematically in Fig. 7. Considering option 3, work is lost to force the solvent (wa-... 

Fig. 7. a Locations for the large losses of exergy in crystallization of amino acids using a water-miscible cosolvent (shaded boxes), b Locations for the small losses of exergy in crystallization of amino acids using a selective (e.g., nano-filtration) membrane... 

Because of the water-solubility of HMMM resins, they can be used with water-reducible alkyds, polyesters or acrylics and with acrylic copolymer latices to produce water-based counterparts of the above stoving finishes. While the reduction in solvent is substantial, such coatings are not usually free of small proportions of water-miscible cosolvents, e.g. 2-butoxy ethanol, and ammonia or amines (pp. 119, 120). An example of a water-reducible polyester-MF stoving finish is given in Table 13.5. 

The variation of the refractive index, n, between that of water and that of the neat water-miscible cosolvents does not exceed 13% (Table 3.5). Hence for some purposes, linear interpolation according to the mole fractions provides a sufficiently good approximation for of the mixture. A better one is obtained when is back-calculated from the molar refraction, assumed to be independent of the arrangements and bonding of the atoms, according to ... 

Abstract The in vitro enzyme-mediated polymerization of vinyl monomers is reviewed with a scope covering enzymatic polymerization of vitamin C functionalized vinyl monomers, styrene, derivatives of styrene, acrylates, and acrylamide in water and water-miscible cosolvents. Vitamin C functionalized polymers were synthesized via a two-step biocatalytic approach where vitamin C was first regioselectively coupled to vinyl monomers and then subsequently polymerized. The analysis of this enzymatic cascade approach to functionalized vinyl polymers showed that the vitamin C in polymeric form retained its antioxidant property. Kinetic and mechanistic studies revealed that a ternary system (horseradish peroxidase, H2O2, initiator fS-diketone) was required for efficient polymerization and that the initiator controls the characteristics of the polymer. The main attributes of enzymatic approaches to vinyl polymerization when compared with more traditional synthetic approaches include facile ambient reaction environments of temperature and pressure, aqueous conditions, and direct control of selectivity to generate functionalized materials as described for the ascorbic acid modified polymers. 

Kaha et al. [29] reported that horseradish peroxidase type II gave the best yield, polydispersity, and tacticity in the enzyme-mediated free radical polymerization of methyl methacrylate in mixtures of water and water-miscible cosolvents, when compared with horseradish peroxidase type I, soybean peroxidase, and Arythomyces ramosus peroxidase. The polymerization of methyl methacrylate has predominantly shown the formation of syndiotactic polymers. Changing the enzyme concentration from 70 to 80 mg/mL in a given... 

---