Subject insoluble substrates

Color Additives. The FDA has created a unique classification and strict limitations on color additives (see also CoLORANTS FOR FOOD, DRUGS, COSMETICS, AND MEDICAL DEVICES). Certified color additives are synthetic organic dyes that ate described in an approved color additive petition. Each manufactured lot of a certified dye must be analyzed and certified by the EDA prior to usage. Color lakes are pigments (qv) that consist of an insoluble metallic salt of a certified color additive deposited on an inert substrate. Lakes are subject to the color additive regulations of the EDA and must be certified by EDA prior to use. Noncertifted color additives requite an approved color additive petition, but individual batches need not be EDA certified prior to use. 

Phenol, the simplest and industrially more important phenolic compound, is a multifunctional monomer when considered as a substrate for oxidative polymerizations, and hence conventional polymerization catalysts afford insoluble macromolecular products with non-controlled structure. Phenol was subjected to oxidative polymerization using HRP or soybean peroxidase (SBP) as catalyst in an aqueous-dioxane mixture, yielding a polymer consisting of phenylene and oxyphenylene units (Scheme 19). The polymer showed low solubility it was partly soluble in DMF and dimethyl sulfoxide (DMSO) and insoluble in other common organic solvents. 

In order to conduct research studies on this novel lipid mediator, it is necessary to have available a sufficient quantity of purified, well-defined material. This has not been an easy task, but an approach to preparation of sphingosine-l-P in milligram amounts was outlined by Van Veldhoven et al. (1989). In this procedure, a commercial preparation of sphingosylphospho-choline (which contains a free amine group due to removal of a fatty acyl residue from initial substrate, sphingomyelin) is incubated with phospholipase D in an ammonium acetate buffer at pH 8.0 for 1 hr. An insoluble reaction product is collected and subjected to purification by dissolution in water at room temperature followed by cooling to 4°C. A precipitate forms again and is collected and treated in a similar manner as above except that acetone is used as the solvent. 

Color lakes are pigments that generally consist of an insoluble metallic salt of a certified color additive deposited on an inert substrate. These lakes are subject to the color additive regulations of the FDA and must be certified by the agency prior to use. 

The most familiar transitions between surface phases in fluid interfaces are those in the so-called insoluble monomolecular films that some higher alcohols and fatty adds form at a water-air interface. Distinct surface phases and transitions between them are frequently observed also in monolayers of adsorbed gases on solid substrates, and are the subject of an exuberant modem literature. ... 

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