Solutions and Suspensions

Ramsden W 1903 Separation of solids In the surface layers of solutions and suspensions Proo. R. Soo. 72 156-64... 

Azobisnittiles are efficient sources of free radicals for vinyl polymerizations and chain reactions, eg, chlorinations (see Initiators). These compounds decompose in a variety of solvents at nearly first-order rates to give free radicals with no evidence of induced chain decomposition. They can be used in bulk, solution, and suspension polymerizations, and because no oxygenated residues are produced, they are suitable for use in pigmented or dyed systems that may be susceptible to oxidative degradation. 

Physical Properties. The physical form and stabiUty of a fertilizer product is of an importance almost equal to that of its chemical content. Commercial fertilizers of importance include not only soHds, but also fluids, both solutions and suspensions, and even a gas (anhydrous ammonia). 

Because of the multiple conjugated olefinic stmcture in the molecule, pure crystalline carotenoids are very sensitive to light and air and must be stored in sealed containers under vacuum or inert gas to prevent degradation. Thus, commercial utilization as food colorings was initially limited however, stable forms were developed and marketed as emulsions, oil solutions and suspensions, and spray-dried forms. 

Annatto extract is sold ia several physical forms, including dry powders, propylene glycol/monoglyceride emulsions, oil solutions and suspensions, and alkaline aqueous solutions containing anywhere from 0.1—30% active colorant calculated as bixia, norhixin, as appropriate. It... 

Fig 3 Comparison of Homogeneous Solution and Suspension Counting of Tagged HMX Samples... 

The different salts, esters, ethers, isomers, mixtures of isomers, complexes or derivatives of an active substance shall be considered to be the same active substance, unless they differ significantly in properties with regard to safety and/or efficacy, in which case additional safety and efficacy data are required. The same qualitative and quantitative composition only applies to the active ingredients. Differences in excipients will be accepted unless there is concern that they may substantially alter the safety or efficacy. The same pharmaceutical form must take into account both the form in which it is presented and the form in which it is administered. Various immediate-release oral forms, which would include tablets, capsules, oral solutions and suspensions, shall be considered the same pharmaceutical form for this purpose. 

Profiles of pH versus solubility and pH versus stability are needed for solution and suspension formulations to help assure physical and chemical stability as well as to maximize or minimize solubility. This information is also valuable for predicting the compatibility of drugs with various infusion fluids. 

The therapeutically inactive ingredients in ophthalmic solution and suspension dosage forms are necessary to perform one or more of the following functions adjust concentration and tonicity, buffer and adjust pH, stabilize the active ingredients against decomposition, increase solubility, impart viscosity, and act as solvent. The use of unnecessary ingredients is to be avoided, and the use of ingredients solely to impart a color, odor, or flavor is prohibited. 

We can readily polymerize styrene by a variety of methods including solution, emulsion, suspension, and bulk processes. Historically, bulk polymerization was the first commercial process, but it has now largely been superseded by solution and suspension polymerization. 

The freezing of complex organic solutions and suspensions is often difficult to predict theoretically. The methods to analyze the freezing process and the formed structure are described in Section 1.1.5. The freezing is influenced by several factors, which often act in opposing directions ... 

For solutions and suspensions the solid content has to be recognized. This is reflected in Eq. (2)... 

An electrical potential develops at all interfaces. In soil, there are interfaces between solids and solution, solution and suspension, suspension and the electrode surface, and between the reference electrode and all these interfaces. 

Numerous types of electrodes are used for soil analysis. Simple elemental electrodes such as platinum, mercury, and carbon are the most frequently used, while other unreactive metals such as gold and silver and the more reactive copper and zinc and others have also been used. Both stirred and unstirred solutions and suspensions are used during analysis. In some cases, electrodes are rotated or, in the case of mercury, dropped into the solution being analyzed. 

Physiochemical properties of the test material should be a major consideration in selection of drinking water as a dosing matrix. Unlike diet preparation or preparation of gavage dose solutions and suspensions where a variety of solvents and physical processes can be utilized to prepare a dosable form, preparations of drinking water solutions are less flexible. Water solubility of the test chemical is the major governing factor and is dependent on factors such as pH, dissolved salts, and temperature. The animal model itself sets limitations for these factors (acceptability and suitability of pH and salt-adjusted water by the animals as well as animal environmental specifications such as room temperature). 

If you watch a glass of muddy water, you will see particles in the water settling out. This is a heterogeneous mixture where the particles are large (in excess of 1000 nm), and it is called a suspension. In contrast, dissolving sodium chloride in water results in a true homogeneous solution, with solute particles less than 1 nm in diameter. True solutions do not settle out because of the very small particle size. But there are mixtures whose solute diameters fall in between solutions and suspensions. These are called colloids and have solute particles in the range of 1 to 1000 nm diameter. Table 131 shows some representative colloids. 

Vand, V. J. Phys. Coll. Chem. 52 (1948) 277. Viscosity of solutions and suspensions. 

Oral solutions and suspensions Appearance, precipitation, pH, color, odor, redispersibility (suspensions), and clarity (solutions)... 

W. Ramsden Separation of Solids in the Surface-Layers of Solutions and Suspensions — Preliminary Account. Proc. R. Soc. 72, 156 (1903). 

The most important commercial processes for polyacrylonitrile (XLIII) are solution and suspension polymerizations. Almost all the products containing acrylonitrile are copolymers. Styrene-acrylonitrile (SAN) copolymers are useful as plastics (Sec. 6-8a). 

Regulatory expectations for microbial bioburden for nonsterile pharmaceutical products are reviewed using the FDA guide to inspections of microbiological quality control laboratories [2], purified water systems [27], topical products [28], and oral solutions and suspensions [29]. 

In the guide to inspection of oral solutions and suspensions [29], it is stated that in some oral liquids microbiological contamination can present significant health hazard. For instance, microbiological contamination with gram-negative... 

U.S. Food and Drug Administration (FDA) (1994), Guide to inspection of oral solutions and suspensions, FDA, Rockville, MD. 

Oral Solutions and Suspensions Formation of precipitate, clarity for solutions, pH, viscosity, microbial bioburden, extractables, and polymorphic conversion when applicable. Additional tests for suspensions include redispersability, rheological properties, mean size, and distribution of particles. 

Powders for Oral Solutions and Suspensions Water content, reconstitution time, and reconstituted solutions and suspensions should be tested as above for oral solutions and suspensions. 

Liquid medicines generally include oral liquids, suspensions, emulsions, inhalations, nasal solutions and suspensions, topical semisolids and topical liquids, ophthalmics, and parenterals. There are numerous excipients used for liquid... 

High ophthalmic solutions and suspensions, trans-dermal ointments and patches, nasal aerosols and sprays... 

Low topical solutions and topical powders oral tablets and oral suspensions topical oral powders (hard and soft and lingual aerosols gelatin), capsules, oral solutions, and suspensions... 

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