Physical Pharmacy SOLUBILIZATION

1. Physical PharmacySOLUBILIZATION By Abdul-WahhabKhedr Demonstrator of Pharmaceutics & Industrial Pharmacy

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

3. Determination of Solubility of Benzoic acid • Procedure: • In a glass bottle, add 0.5 gm benzoic acid & 20 ml distilled water. • Shake for 10 min and set aside for another 10 min. • 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). • The End Point is determined by the appearance of the first permanent faint pink colour. • Repeat the above steps using surfactant solutions (1%, 3%, 5%, 7%) instead of distilled water and determine the end points.

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

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 + H2O 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: Then draw the relationship between surfactant concn (on x-axis) and solubility (on y-axis).