1. SOLUBILIZATION Physical Pharmacy SOLUBILIZATION By Abdul-Wahhab Khedr Demonstrator of Pharmaceutics & Industrial Pharmacy

2. Definition: Solubilization Solubilization is the process of bringing into solution substances which are insoluble or sparingly soluble in water. Methods of Solubilization: 1)The use of mixed solvents (blending and Co-solvency). 2)The use of surface active agents (Micelle formation). 3)The use of hydrotropic salts e.g. iodine and potassium iodide. 4)Complex formation e.g. caffeine and barbiturate.

3. Determination of Solubility of Benzoic acid Procedure: Procedure: 1.In a glass bottle, add 0.5 gm benzoic acid & 20 ml distilled water. 2.Shake for 10 min and set aside for another 10 min. 3.Filter the contents of the bottle, take 10 ml of the filterate and titrate with 0.1 N NaOH using Ph.Ph. as indicator (3-5 dps). 4.The End Point is determined by the appearance of the first permanent faint pink colour. 5.Repeat the above steps using surfactant solutions (1%, 3%, 5%, 7%) instead of distilled water and determine the end points.

4. E.P = Volume of titrant used 0.5 gm benzoic acid 20 ml dist. Water or sample soln Shake for 10 minSet aside for 10 min 10 ml of filterate 3 dps Ph.Ph 0.1 N NaOH Procedure Filter

5. Calculation of Solubility Factor (F): is the amount of benzoic acid (in grams) neutralized by 1 ml of titrant (0.1 N NaOH). Calculation of Factor (F): + NaOH + H 2 O 1 mole benzoic acid ≡ 1 mole NaOH 122 gm ≡ 1000 ml 1 M NaOH 122 gm ≡ 1000 ml 1 N NaOH 122 /10 ≡ 1000 ml 0.1 N NaOH F ≡ 1 ml 0.1 N NaOH

6. Calculation of Solubility Results: Solubility (g/l)E.P Surfactant Conc n 1 % 3 % 5 % 7 % Then draw the relationship between surfactant conc n (on x-axis) and solubility (on y-axis).