The release of electrolytes from multiple emulsions can be a result of the instability of the multiple droplets or diffusion through the oil-layer membrane. It was confirmed exptl. that, in the multiple system examd., the diffusion mechanism is the detg. factor in the release pattern of these electrolytes. The release is affected by the hydrophobicity of the electrolyte and by its concn., but not by the viscosity of the internal phase. Therefore, from a practical point of view it is not enough to obtain stable multiple emulsions; limiting and controlling the diffusion has also to be considered. [on SciFinder(R)]

Multiple (water-in-oil-in water) emulsions were prepd. by homogenizing 30 parts 1% NaCl with 70 parts of light mineral oil contg. varying amts. of Brij 92 emulsifier and then adding 20 parts of this primary emulsion to 80 parts of 5% glucose contg. varying amts. of mixts. of Span 20 [1338-39-2] and Tween 80 [9005-65-6] to provide hydrophile-lipophile balance (HLB) values of 9-15. At Tween-Span emulsifier mixt. concns. of 0.7-1.5% the yield of multiple emulsion was not affected by HLB value; droplet size detd. the yield. At emulsifier concns. \textgreater1.5% the yield decreased with increasing concn. at any HLB, related to a continuous decrease in multiple emulsion droplet size. Yields and emulsion stability were max. with an HLB value of 11 at emulsifier concns. \textgreater1.5%; at emulsifier mixt. concns. of 0.7-3% stability increased with increasing HLB value. Multiple emulsions are promising pharmaceutical forms. [on SciFinder(R)]

The optimal HLB for multiple emulsions was investigated and found dependent on the concns. of emulsifiers I and II. The shift of the optimal HLB at different emulsifier concns. is a result of the free emulsifier I which exists in the oil phase of the primary emulsion. A linear correlation between the optimal HLB, the concn. of emulsifier II, and the reciprocal concn. of emulsifier I is obsd. Yields of prepn. of the multiple emulsions were detd. by a chloride titrn. and cond. measurement, without using a dialysis cell. [on SciFinder(R)]

Polymorphic transitions between the cryst. forms 4, 5, and 6 of coca butter (m. 27.5, 33.8, and 36.3°, resp.) were studied by differential scanning calorimetry and x-ray diffraction. The transitions were modified by surfactants of the Span and Tween type, mostly in favor of form 5. Expts. were also carried out on chocolate. There was little relation between polymorphic transition and bleaching. Bleaching seemed, however, related to the rate of cooling, and was due to the migration of a molten cocoa butter fraction to the surface. [on SciFinder(R)]

The exptl. conditions to maintain metastability in a soln. of Ca oxalate during 15 min were defined. Seed crystals of uric acid and Na urate were added, and the decrease in Ca ion concn. was measured by a Ca-selective electrode. Na urate crystals caused a decrease of ∼14%, while uric acid seeds were inactive. The growth of Ca oxalate on Na urate surface was confirmed by x-ray emission anal. When glutamic acid was added at 4-5 ppm concn. to the metastable soln. contg. uric acid seeds, a ∼28% Ca-concn. decrease was obsd. The pptn. of Ca oxalate on uric acid was confirmed by x-ray emission anal. A structural fit at an at. level between 2 solids, which is a necessary condition for epitaxy, is not sufficient for growth to occur. An addnl. factor, namely attraction at an ionic or mol. level, is also needed. It may be furnished by a mediating agent compatible with both solids. [on SciFinder(R)]

The effects of L-aspartic acid, alanine, and L-glutamic acid on the crystn. of Ca oxalate were followed by 2 methods. Glutamic acid (0-200 ppm) was added to solns. of CaCl2 which were subsequently mixed with solns. of Na2C2O4 to yield CaC2O4 pptn. At relatively high concns. of glutamic acid (20-200 ppm), the pptn. of Ca oxalate is retarded. However, at low concns., 2.5-20 ppm, oxalate pptn. is enhanced. The 2 independent methods yield well-correlated results. Both L-aspartic acid and alanine did not affect the pptn. of Ca oxalate. The results are discussed with respect to renal calculi formation. [on SciFinder(R)]

Brominated Span 80, brominated Tween 80, brominated oleic acid, and brominated linoleic acid function as emulsifiers and weighting agents in castor oil-in-water emulsions and increase the sp. gr. of oil droplets. Stable emulsions are obtained at appropriate concns. of emulsifiers, and downward creaming (sedimentation) occurs when larger concns. of weighting agents-emulsifier are used. The efficiency of the weighting agent-emulsifier depends on the sp. gr., HLB value, and water soly. Brominated oleic and linoleic acids (in presence of triethanolamine) are the most efficient because they are hydrotropic and are adsorbed in the oil-water interface or dissolved in the oil. [on SciFinder(R)]

Inversion of multiple W/O/W emulsions into O/W systems was studied as a function of the HLB of the external emulsifier, its concn., and droplet size. Inversion occurs only when droplet size is reduced under crit. size or if the HLB of the total emulsifiers present in the system (weighted HLB) approaches the required HLB of the oil phase. Inversion is independent of the HLB of the external emulsifier by itself (apparent HLB). [on SciFinder(R)]