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40 Cards in this Set
- Front
- Back
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oil
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lipid or nonaq
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w/0
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internal phase - h20
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o/w
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external phase - h2o
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type of emulsion formed is determined by - Ideal Emulsion
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- relative phse volumes emulsifying agt
max conx of internal phase is 74% -> < or eq 74% oil |
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choice of emulsifying agt
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more impt than the relative phase volumes in determining final emulsion type
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emulsifying agt
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any compd that lowers the interfacial tension and forms a film at the interface
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effectiveness of emulsifying agt
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depends on
chemical structure conc solubility pH physical prop electrostatic eff |
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true emulsifying agt ( primary agts)
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form and stabilize emulsions by themselves
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stabilizers(auxilliary agts)
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do not form acceptable emulsions when used alone but assist primary agts in stabilizing the prodt
ex: inc viscosity |
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emulsifying agts
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natural
synthetic |
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natural emulsifying agts
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acacia
tragacanth agar pectin gelatin methylcellulose carboxymethylcellulose |
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synthetic emulsifying agts
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anionic
cationic nonionic |
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acacia
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good
stable emulsion of low viscosity cream easily incompatible w/ peruvian balsam, salts and carbonates acidic stable at pH 2-10 negatively charged dehydrates easily requires preservative |
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tragacanth
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stable smulsion
coarser than acacia ionic and difficult to hydrate used for eff on viscosity less than or eq to 1/10 of amt used for acacia needed |
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agar
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anionic gum
inc viscosity stability affected by heating, dehydration and destruction of charge susceptible to miscrobial degradation |
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pectin
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quasi-emulsifier
used in the same proportion as tragacanth |
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gelatin
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provides good emulsion stabilization in a conc of 0.5%-1%
depends on isoelectric pt could be anionic or cationic |
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type a gelatin(+)
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prepared from acid treated precursor
used in acidic media |
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type B gelatin (+)
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prepared fr alkai treated precursor : used in basic med
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methylcellulose
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nonionic
induces viscosity used as 1 degree emulsion w/ mineral oil and cod liver oil yields o/w emulsion used in 2% conc |
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carboxymethylcellulose
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anionic
used to inc viscosity tolerates alc up to 40% forms basic soln precipitates in presence of free acids |
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surfactants
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amphiphilic molecules
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HLB balance
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imbalance of surfactants
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0-3
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antifoaming agt
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4-6
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w/o emulsifying agt
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7-9
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wetting agt
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8-18
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o/w emulsifying agt
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13-15
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detergents
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10-18
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solubilizing agts
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anionic synthetic agts
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sulfuric acid esters (sod lauryl sulfate)
sulfuric acid deriv (dioctyl sod sulfosuccinate) soaps |
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soaps
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externaluse
inc pH sensitive to the addition of acids and electrolytes |
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alkali soaps
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hydrophilic
form o/w emulsion |
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metallic soaps
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o/w emulsion
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monovalents soaps
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o/w emulsion
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polyvalent soaps
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w/o emulsion
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cationic synthetic agts
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benzalkonium cl
used as surface active ing in 1% conc incompatible with soaps |
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nonionic syn agts
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resistant to the addition of acid and electrolytes
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sorbitan esters
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spans
low HLB value (1-9) hydrophilic form w/o emulsion |
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tweens
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polysorbates
hydrophilic o/w emulsion form complexes w/ phenolic compd inc hlb calue (11-20) |
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prepare emulsion
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wet gum (english) mtd
dry gum (continental) mtd bottle mtd nascent soap mtd |
