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10 Cards in this Set
- Front
- Back
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water of imbibition
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held in fissures and pores
may promote chem reaction |
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types of dispersed systems
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molecular dispersion-homogenous solution; invisible under EM
colloidal dispersion: slow particle diffusion...polymer sol'ns coarse dispersion: susp, emulsion |
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formulation consideration for orally administered suspensions
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active
wetting agent flocculating agent suspending agent (v enhancing) colorant sweetener acidifier purified water |
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contact angle measurement
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high=insignificant or no wetting
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nonionic surfactants
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pluronics/poloxamers: linear block copolymer
spans: partial esters of fatty acids and hexitol anhydride tweens/polysorbates: derived from spans..more alkyl gps |
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ionic surfactants
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anionic: sodium lauryl sulfate: topical eg soaps
Cationic: Hexadecyltrimethyl ammonium bromide |
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HLB value for surfactants
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hydrophilic-lipophilic balance: how decide which to use
value of 1-9 good for just wetting value of 10-18 can solubilize |
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HLB equation
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Say Sodium Lauryl sulfate has a +38.7 value for hydrophilic group contribution to HLB,
HLB=7+ sum of hydrophilic group # + sum of lipophilic group # =7 + 38.7 + (12*-.475) |
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a flocculating agent is used for controlled flocculation. What is the affect on zeta potential?
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since you are adding a cationic adsorbent and anionic flocculant (or vice versa-either way, are increasing electrolyte concentration), the zeta potential is decreased.
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type of flocculating agent to use
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multivalent is most effective, but compatibility problems arise
combo of ionic or nonionic surfactants used with lipophilic polymers |
