Gel-forming polymers

The potential profile through the membrane that is placed between the sample and the internal reference solution was shown in Fig. 6.3. The composition of the internal solution can be optimized with respect to the membrane and the sample solution. In the interest of symmetry, it is advisable to use the same solvent inside the electrode as is in the sample. This solution also contains the analyte ion in the concentration, which is usually in the middle of the dynamic range of the response of the membrane. The ohmic contact with the internal reference electrode is provided by adding a salt that contains the appropriate ion that forms a fast reversible couple with the solid conductor. In recent designs, gel-forming polymers have been added into the internal compartment. They do not significantly alter the electrochemistry, but add mechanical stability and convenience of handling. 

Corn oil is used primarily in pharmaceutical formulations as a solvent for intramuscular injections or as a vehicle for topical preparations. Emulsions containing up to 67% corn oil are also used as oral nutritional supplements see also Section 18. When combined with surfactants and gel-forming polymers, it is used to formulate veterinary vaccines. 

Phase transfer catalysis is a significant advance in preparative organic chemistry, but there is a practical limitation—phase transfer agents sometimes stabilize emulsions, which make product recovery difficult. A variation of the technique, called triphase catalysis, involves bonding the phase transfer agent to a support, such as a gel-form polymer (see 14.2.4.1) . If the polymer has an affinity for boA liquid phases, the phase... 

Structure-Forming Excipient—Excipient that participates in the formation of the structural matrix that gives an ointment, cream, gel, etc., its semisolid character. Examples are gel-forming polymers, petrolatum, certain colloidal inorganic solids (e.g., bentonite), waxy solids (e.g., cetyl alcohol, stearic acid), and emulsifiers used in creams. 

Eggink, G., de Wolf, E.A. et al (2011) Secreted production of collagen-inspired gel-forming polymers with high thermal stabihty in Pichia pastoris. Biotechnol. Bioeng., 108, 2517—2525. 

Solis, F.J., Weiss-Malik, R. Vernon, B. 2005, Local monomer activation model for phase behavior and calorimetric properties of LCST gel-forming polymers . Macromolecules, vol. 38, no. 10, pp. 4456-4464. 

---