Semisolids, compounding

These are semisolid or solid substances formed in nature from crude oils after the volatile components have evaporated and the remainder has undergone oxidation and polymerization. They are also referred to as bitumens, waxes, and pitch. These materials are believed to consist of mixtures of complex organic molecules of high molecular weight. As with crude oils, which contain thousands of different chemical compounds, an exact chemical analysis for identification and composition is impractical to perform on the solid deposits of petroleum. 

Studies designed to improve the determination of environmental contaminants will continue to provide refinements and improvements in the determination of acrylonitrile. The current high level of activity in supercritical fluid extraction of solid and semisolid samples should yield improved recoveries and sensitivities for the determination of acrylonitrile in solid wastes, and the compound should be amenable to supercritical fluid chromatographic analysis. Immunoassay analysis is another area of intense current activity from which substantial advances in the determination of acrylonitrile in environmental samples can be anticipated (Vanderlaan et al. 1988). 

In order to prepare the samples for dielectric-constant measurements, etherdiacrylate 6 was mixed with a trace amount of AIBN at room temperature in a cylindrical donut mold made from General Electric RTV 11 silicon molding compound. The donuts had an outer diameter of 7.0mm, an inner diameter of 3.0 mm, and a thickness of 3.0 mm the semisolid triacrylate 3 was mixed with a... 

Electrophoresis Solid or semisolid in a buffer solution Electricity Compounds or ions must be ionized to be separated. 

The practicing pharmacists may be called upon to prepare a semisolid dosage form in large quantity. The formulae for such preparations, in general, indicate proportional parts (or relative quantities) of ingredients to be used in compounding the desired total quantity. 

Capsules are dosage forms in which unit doses of powder, semisolid, or liquid drugs are enclosed within a hard or a soft envelope, or shell. Examples of currently compounded capsules are given in Table 1 with the contents as powders, in oil, or in a semisolid-filled capsule, and modified strength capsules. 

These are areas where personnel could come into direct contact with open materials (starting materials, intermediate product, bulk product, and open primary packaging materials), for example, all operations (sampling, compounding, and producing) for manufacturing of solids, semisolids, and liquids for oral and topical use. 

Preservatives such as sodium benzoate, sorbic acid, and methyl and propyl parabens have been used in liquid and semisolid dosage forms. There have been reports that the parabens have been inactivated when used in the presence of various surfactants. This loss of activity was thought to be due to the formation of complexes between the preservative and the surfactant. The interaction between polysorbate (Tween) 80 and the parabens has been demonstrated by a dialysis technique (Ravin and Radebaugh, 1990). It has also been shown that molecular complexes form when the parabens are mixed with polyethylene glycol (PEG) and methylcellulose. The degree of binding was less than that observed with Tween 80. Sorbic acid also interacts with Tweens but does not interact with PEGs. The quaternary ammonium compounds are also bound by Tween 80, which reduces their preservative activity. 

Capabilities—solid dosage, sterile products, liquids/semisolids, potent compound, different licensure (DEA, etc.)... 

Semisolid petroleum jelly is a highly refined product commonly known as vaseline, a mixture of predominantly C16-C19 alkanes. Carefully controlled refining processes are used to remove nitrogen and sulfur compounds, resins, and unsaturated hydrocarbons. Paraffin wax is a similar product, behaving as a solid. Neither petroleum jelly nor paraffin is digested or absorbed by the body. 

Tetraphenylethane [21]. Diphenylmethane (4g) and p-benzoquinone (1.2g) in thiophene-free, sodium-dried benzene (20g) were exposed to sunlight for one month in Cairo. The reaction was carried out in a sealed glass tube filled with carbon dioxide. Quinhydrone began to separate out after only an hour after a month the complete precipitate was filtered off. The benzene was evaporated under vacuum and the oily residue steam-distilled, in order to remove diphenylmethane and p-benzoquinone, and then ether extracted. The extract was dried (sodium sulfate) and the ether removed under vacuum. The residue was extracted with petroleum ether. A semisolid mass was obtained which was recrystallized from petroleum (100-110°) to give colorless crystals of the title compound (m.p. 210°, yield 0.7 g). 

Gels are of central importance for most semisolid food products. A gel can contain more than 99% water and still retain the characteristics of a solid. The network structure will determine whether the water will be firmly held or whether the gel will behave more like a sponge, where water is easily squeezed out. The gel structure will also have a major impaet on the texture as well as diffusion of water and soluble compounds. Many food matrixes are based on colloidal gels such as yoghurts, cheeses, many desserts, sausages etc (see also Chapters 19 and 20). In whole foods, there is often a combination of colloidal structures and fragments of biological tissues or gel structures in combination with particles, emulsion and foam structures. This level of complexity of composite food structures will not be dealt with here. 

Compressed gas systems were originally developed simply to provide a means of expelling a product from its container when the valve was depressed. Semisolid products such as a cream, ointment, or caulking compound are dispensed as such. A liquid concentrate and a compressed gas propellant (Fig. 3) produce a spray when a mechanical breakup actuator is used. Nitrogen, insoluble in most materials, is generally used as the propellant. 

Petroleum depoeite are naturally occurring mixtures of organic compounds found within, the strata of the earth. Those that occur in the gaseous state are generally referred to as natural gas whereas those occurring as liquids are kndSi. as petroleum oil or crude oil. Solid deposits are known as tars and asphalts, but, smce many of these are actually semisolids or plastic solids, they should be classified as such. 

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