Carboxymethyl cellulose insolubility

Sodium carboxymethyl cellulose [9004-32-4] (CMC) and hydroxyethyl cellulose [9004-62-0] (HEC) are the ceUulosics most widely used in drilling fluids (43). CMC is manufactured by carboxymethylation of cellulose which changes the water-insoluble cellulose into the water-soluble CMC (44). Hydroxyethyl cellulose and carboxymethyl hydroxyethyl cellulose (CMHEC) are made by a similar process. The viscosity grade of the material is determined by the degree of substitution and the molecular weight of the finished product. 

Fluid loss additives such as solid particles and water-thickening polymers may be added to the drilling mud to reduce fluid loss from the well bore to the formation. Insoluble and partially soluble fluid loss additives include bentonite and other clays, starch from various sources, crushed walnut hulls, lignite treated with caustic or amines, resins of various types, gilsonite, benzoic acid flakes, and carefully sized particles of calcium borate, sodium borate, and mica. Soluble fluid loss additives include carboxymethyl cellulose (CMC), low molecular weight hydroxyethyl cellulose (HEC), carboxy-methYlhydroxyethyl cellulose (CMHEC), and sodium acrylate. A large number of water-soluble vinyl copolymers and terpolymers have been described as fluid loss additives for drilling and completion fluids in the patent literature. However, relatively few appear to be used in field operations. 

Cellulose disintegrants have been studied as insoluble matrices for sustained release tablets. Anionically charged carboxymethyl cellulose (sodium salt) was found to be inferior to methyl cellulose and poly(vinyl pyrollidone) as a binding agent for oxyphenbutazone tablets [291], However sodium carboxymethyl cellulose has found application as a dispersing agent for ibuprofen microspheres... 

A combination of osmotic and swelling effects was used in the system developed by Amidon and Leesman. " The permeability-controlled systems consisted of a core, containing an osmotically active substance, a swelling substance, and the drug. NaCl and sorbitol were used as osmotic substances and Na carboxymethyl cellulose as the swelling material. These cores were coated with an insoluble, semipermeable polymer, such as cellulose acetate. The time Tp, when the insoluble film ruptured, was described by the following equation ... 

Carrot fiber, prepared as an alcohol-acetone insoluble residue of cell wall material, binds deoxycholate and chenodeoxycholate under physiological conditions with the release of protons. Removal of calcium pectate from this material by extraction with ammonium oxalate reduces the capacity of carrot fiber to bind bile acids. Calcium carboxymethyl cellulose exhibits similar binding activity, whereas free carboxymethyl cellulose shows no binding. Calcium pectate prepared from citrus pectin and dissolved in water was found to bind bile acids under conditions used with carrot fiber. These results suggest that binding occurs through formation of salt linkage between calcium pectate in the cell wall residue and a bile acid. 

Enzymes have been bound to insoluble cellulose derivatives by various methods such as (a) to insoluble carboxymethyl cellulose using the azide derivative, (b) to insoluble cellulose using the diimide reaction, etc. More recently H. Weetall described the covalent coupling of 1-amino-acid oxidase to porous silica glass particles. 

Carboxymethyl cellulose is an anionic water soluble polymer capable of forming very viscous solutions. Carboxymethyl cellulose is soluble in basic conditions and insoluble in acidic conditions. It is used as a thickener, stabilizer, and suspending agent Carboxymethyl cellulose inhibits ice crystal growth in frozen desserts and soft serve ice cream. It is also used to improve loaf volume during baking by stabilizing gas bubbles. 

The cellulose ethers constitute another important group of cellulose derivatives prepared from alkali cellulose by standard etherification reactions between the hydroxyl groups and an alkyl halide. The properties of the ethers depend on the extent of the reaction that is, the degree of etherification. In general, the ethyl celluloses are water-insoluble thermoplastic materials, whereas methyl ether, ethyl hydroxyethyl cellulose, and carboxymethyl cellulose are soluble in cold water and are used as viscoelastic thickeners and adhesives. 

Blinders are chemicals, usually polymers, which are used to adsorb onto undesired mineral components that would otherwise adsorb collectors. An example is the addition of carboxymethyl cellulose (CMC) to potash slurry. The CMC adsorbs onto insoluble minerals, preventing amine collector from being adsorbed and preventing flotation of the undesired minerals. This process is termed blinding. 

The presence of soluble impurities can also affect the induction period, (section 5.5), but it is virtually impossible to predict the effect. Ionic impurities, especially Fe + and Cr +, may increase the induction period in aqueous solutions of inorganic salts. Some substances, such as sodium carboxymethyl-cellulose or polyacrylamide, can also increase whereas others may have no effect at all. The effects of soluble impurities may be caused by changing the equilibrium solubility or the solution structure, by adsorption or chemisorption on nuclei or heteronuclei, by chemical reaction or complex formation in the solution, and so on. The effects of insoluble impurities are also unpredictable. 

The non-ionic cellulose ethers do not form irreversible, insoluble, complexes with metal ions (in contrast to sodium carboxymethyl cellulose), but may be precipitated by high concentrations of salts. CMC forms a gel when reacted with divalent ions like Ca (Clasen and Kulicke, 2001). CMC will react with iron, alu-... 

Since our crude material extracted from the intestinal mucosa for the preparation of secretin contained cholecystokinin and pancreozymin as well, the methanol-insoluble material left after extracting the secretin was fractionated with ethanol and chromatographed on carboxymethyl cellulose. The material obtained could be used in man (Werner and Mutt 1954, Werner 1956), 3-4 mg of substance being injected intravenously for the cholecysto-graphic test. The cholecystokinin activity was 22 Ivy dog imits/ mg and the pancreozymin activity 100-120 units/mg as defined by Grick, Harper and Raper (1949) (Jorpes and Mutt 1959, 1961 a). 

The key consideration in the analysis of any sustained release dosage form as previously discussed (see Sections II.A, II.B, II.C.l, and II.C.2rg) is to determine what solvent or solvent system will be most appropriate to assure the dissolution of the drug and its excipients to make it amenable to HPLC analysis. Aqueous solubility of weak acids and bases is governed by the pfCa of the compound and the pFI of the medium. In an acidic or low pFI medium, weak acids will be unionized and will be more soluble in organic solvents. The reverse is the case for basic compounds as previously discussed in Section II.B. Because the formulation of sustained release dosage forms tend to rely on the use of insoluble plastics (i.e., methyl acrylate-methyl methacrylate, polyvinyl chloride, and polyethylene), hydrophilic polymers (i.e., methylcellulose, hydroxypropyl-methylcellulose, sodium carboxymethyl cellulose, and carbopol 934), and fatty compounds (i.e., waxes such carnauba wax and glyceryl tristearate), similar hydro-organic solvents and sample preparation steps that have been discussed for tablets and capsules can also used for their analysis by HPLC (see Sections II.A, II.B, II.C.l, and II.C.2). 

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