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Transcript of Colloidal Dispersion
of colloids and small particles are fundamental to an understanding of the
behavior of pharmaceutical dispersions. COLLOIDAL DISPERSIONS Its physical and chemical properties Objectives To be able to prepare a dispersion medium using chalk, starch, sulfur and ferric hydroxide.
To determine the different characteristics and properties of colloidal dispersion. Concentrated
HCl 1 M Ferric chloride Copper sulfate solution Chalk Distilled water Cobalt nitrate solution 0.1 M Potassium ferricyanide 0.1 M Sodium thiosulfate Starch 3 M Sulfuric acid Sulfur powder Ethyl alcohol Reagents ? SO What are Colloidal Dispersions Dispersion consists of at least two phases with one or more dispersed (internal) phases contained in a single continuous (external) phase. There are 3 classifications of dispersed systems Molecular Coarse Colloidal Particle size Characteristic one colloidal Invisible in electron microscope
Pass through ultrafilter and semipermeable membrane
Undergo rapid dispersion 1 nm - 0.5 um Not resolved by ordinary microscope
Visible in electron microscope
Pass through filter paper
Do not pass through semipermeable membrane
Diffuse very slowly Compare <1 nm coarse molecular Examples >0.5 um Visible under microscope
Do not pass through normal filter paper
Do not dialyze through semipermeable membrane
Do not diffuse It is important to know that the only difference between molecular,
colloidal and coarse dispersions is the size of the dispersed phase and
not its composition. Types of
Dispersions Lyophilic Association Lyophobic Polysterene Interact to an appreciable extent Solvent-loving colloids Organic molecules obtained simply by dissolving the material in the solvent being used gelatin, acacia, insulin, albumin, rubber and polystyrene. inorganic particles Due to the absence of a solvent sheath around the particle Solvent-hating colloids little attraction gold, silver, sulfur, arsenous sulfide and silver iodide. Amphiphiles or surface-active agents Non-ionic have two distinct regions of opposing solution affinities within the same molecule or ion Anionic Cationic Micelles or aggregates may contain 50 or more monomers, occurring over a narrow concentration range as the concentration is increased. CMC and aggregation number Faraday-Tyndall
Effect When a strong beam of light is passed through a colloidal sol, a visible cone, resulting from the scattering of light by the colloidal particles is formed. Light source True solution Colloidal solution Procedure Chalk sol Sulfur sol Starch sol Ferric hydroxide sol Ergo, we conclude that there are different types of dispersion mediums. To mention some, we have chalk sol, starch sol, sulfur sol and ferric hydroxide sol. In addition, one way of determining whether a preparation is a colloid is by observing if it possesses Faraday-Tyndall effect, which is a dominant property of a colloidal dispersion. Basing on our results, all of the prepared sols exhibit Faraday-Tyndall effect except starch sol. chalk shake vigorously Transfer Allow to settle Decant Describe the sol 1/3 spatula of powdered sulfur 3 mL ethanol Stir vigorously 3 times at intervals of about 5 minutes Allow to settle Decant 1 mL of clear liquid Transfer in a test tube w/ 10 mL distilled H2O Mix well Describe the sol Let it stand for 1 hour Describe the sol 100 mL H2O 1 M Ferric chloride Continue boiling for 1 minute Cool at room
temperature 1 M FeCl3 100 mL H2O
at room temp 1 drop
0.1 M K3Fe(CN)6 Prussian blue
(+) free Fe3+ ions Filter 20 mL
each system 1 g of starch 10 mL Stir Describe the sol Compare the two systems Let it stand for at least an hour Describe the sol Tyndall Effect Equipments: Big flashlight Stirring rod Spatula Mortar and pestle Funnel Filter paper Dropper Cardboard Test tubes 250 mL beaker Liposomes Microparticles Nano
crystals Micelles Colloidal carriers Initial Result Final Result System Chalk sol Starch sol Sulfur hydroyl Ferric hydroxide sol Ferric colodail Solution Clear liquid solution with few particles dispersed in the test tube White particles dispersed in test tube Cloudy white solution Cloudy white solution which precipitates Clear bluish white solution No significant change observed Orange solution; with residue No significant change observed No significant change observed Yellow solution; without residues Light source True solution Colloidal solution Chalk sol
Ferric hydroxide sol
Ferric chloride solution
Hydrochloric acid solution
Copper Sulfate Prepared by: GROUP 8 Submitted to: MR. JC Lee therapeutic and diagnostic agents
drug delivery systems
recombinant human insulin
improve bioavailability or therapeutic activity. Importance in Pharmacy Practice