Emulsion stability index

Accelerated stability tests using the emulsion volume index (EVI) Accelerated aging procedure in which an emulsion in a microhematocrit tube is subjected to centrifugal force EVI = (length of emulsion phase/lolul length of column) (% fal/0.9) x 100. A higher EVI indicates a more stable emulsion under the conditions of the test. 

The degree of emulsion stability may be taken as the volume of the opaque phase remaining after time t. Alternatively, the volume of oil separated at infinite time may be used as an index of stability. 

Uses Surfactant, emulsifier, emulsion stabilizer for cosmetics and pharmaceuticals Trade Name Synonyms Atlas G-1702 [Uniqema Uniqema Am. http //www.uniqema.com], G-1702 t[Uniqema Uniqema Am. http //www.uniqema.com], Nikkol GBW-25 [Nikko Chems. Co. Ltd http //www.nikkoi.co.jp/index.htmi]... 

Properties Yel. brittle amorphous lumps or powd. turpentine-like fresh resinous odor sol. in alcohol, acetone insol. in benzene, aryl and aliphatic hydrocarbons, water sp.gr. 1.05-1.09 m.p. 135-150 C soften, pt. 100-130 C iodine no. 112-141 sapon. no. 145-157 ref. index 1.545 Uses Binder in lacquers and paper/picture varnishes emulsion stabilizer in cosmetics natural flavoring agent in alcoholic beverages in food-pkg. adhesives in food-contact coatings... 

Modern analytical ultracentrifuges allow one to follow the separation of emulsions in a quantitative manner. With typical 0/W emulsions, three layers are generally observed A clear aqueous phase an opaque phase consisting of distorted polyhedral oil droplets and a clear separated oil phase, resulting from coalescence of the poly-hedra. The degree of emulsion stability may be taken as the volume of the opaque phase remaining after time t. Alternatively, one may use the volume of oil separated at infinite time as an index for stability. 

The apparent inability to effect larger or demonstrable increases in emulsion stability by the addition of substances which raise the cloud point of the stabilizing molecules may be due to several factors. Increase in aqueous solubility may decrease the concentration of emulsifier at the interface, although interfacial tension measurements do not indicate that this is so as there is an optimal HLB for each oil to achieve stability, any change in HLB by addition of agents which salt-in or salt-out the stabilizing molecules will shift the stability index from the optimum position. 

Emulsions prepared with linear alkanes, n-decane, n-dodecane, and n-tet-radecane yielded stable multiple emulsions with a stability index for 28 days (ESl2s) in the 0.85 to 1.10 range at 25°C. Creaming (sedimentation) was quickly detected (2 hours) at all tested storage temperatures (4°C, 25°C, and 40°C). When the external oil phase (O2) consisted of silicone oils, flumethrin releases were significantly slowed and the drug concentration in the external oil phase remained at very low levels (below 2000 ppm) after 28 days of storage at 25°C. 

The emulsification stability index (ESI) reflects the stability of the emulsion to coalescence. An ESI value is the percent by volume of droplets in the range of 2-20 pm immediately after preparation and after 7 days of storage at room temperature (Fig. 59). A high ESI value indicates better stability to coalesce. It should also be stated that all the emulsions stabilized with >0.5 wt% gum are stable to coalescence. No significant change in droplet size was observed after 15 days of aging. 

Figure 59 Emulsification stability index (ESI) vs. POG concentration in emulsions of 5 wt% tetradecane in water measured 7 days after preparation.

Stability index (ESI) values (Fig. 61). It was shown clearly that the ESI values are lower at elevated pH, both in the presence and in the absence of electrolytes. The absence of electrolytes at pH <6.6 does not seem to improve the stability of the emulsions. Microscopic observations carried out on these emulsions confirmed that the best emulsions are formed at pH 3. Emulsions show no flocculation and are very stable for months. 

Features When used with anionics such as corrosion inhibitors and coemulsifiers, provides emulsion stability with low foaming and good hard water stability Properties Amber cl. oily liq. forms cl. sol n. in min. oils disp. in water sp.gr. 0.96 pH 6 (1% aq.) HLB 10 ref. index 1.44 100% cone. 

Uses Chemical intermediate, raw material for surfactants emulsifier, antistaL emulsion stabilizer in cosmetics in textiles acid scavenger in petrol, prods. epoxy hardener catalyst in mfg. of flexible PU foams vise, index improver for... 

Effective Hamaker constant, 234 Emulsifying activity index, 186,188/ Emulsions, concentrated oil-in-water, effea of interdroplet forces on centrifugal stability, 229-245 Enhancers of taste. See Taste enhancers Enzymatic modification of soy proteins, 181-190... 

Amphotericin deoxycholate in glucose versus amphotericin in nutritional fat emulsion The safety of DAMB prepared in nutritional fat emulsion (a non-approved mode of amphotericin administration) has been reviewed (SEDA-21, 282) (SEDA-22, 285). It is not clear whether it has a better therapeutic index than other formulations, and methods of preparing it have not been standardized. The adverse effects of amphotericin prepared in nutritional fat emulsion have been compared with those of amphotericin prepared in 5% dextrose in two studies. While one of the studies showed a significantly lower frequency of infusion-related reactions and hypokalemia in patients receiving the fat emulsion (49), there were no differences in safety and tolerance between the two formulations in the other study (50). The safety of amphotericin prepared in nutritional fat emulsions has been reviewed (SEDA-21, 282) (SEDA-22, 285). Because of stability concerns and lack of systematic safety data, this form of amphotericin cannot be recommended. 

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