1a)Explain what happens when a saturated salt solution is added to the methylcel
ID: 272769 • Letter: 1
Question
1a)Explain what happens when a saturated salt solution is added to the methylcellulose solution. 1b)What is this effect called?
4.) Name the compound that is responsible for swelling of Tragacanth in water.
Experiment II SUSPENSIONS A study of the Properties of Some Suspending Agents The purposes of these exercises are: (1) to learn the technique of preparation of some suspending agents (methylcellulose, tragacanth, and bentonite), and (2) to study some of the properties of the suspending agents. A suspension is a heterogeneous system containing dispersed solids of such size that they settle. Whether a pharmaceutical suspension is to be taken orally, applied topically, or injected, the dispersed phase should be uniformly distributed in order to insure the administration of a uniform dose. The rate of sedimentation or settling for a suspended phase depends on several factors, which may be controlled by the pharmacist. Suspending agents are physiologically inert substances, which increase viscosity when added to suspensions. On Prolonged standing suspensions tend to cake as some crystals knit together at points of contact. A second, important function of suspending agents is to facilitate redistribution of a suspension on shaking. QUESTIONS Explain what happens when a saturated salt solution is added to the methylcellulose solution. What is this effect called? 1. donvad 2. Define Methylcellulose , U.S.P. 0, Chemical compouho lase A adopl à cer viscous olom op gel. Used as hicko 3. Explain the purpose(s) of benzoic acid and glycerin in Tragacanth Mucilage formulation. nt a. Benzoic Acid:Flocculh b. Glycerin: Viseosty Enhancer Name the compound that is responsible for swelling of Tragacanth in water. ismoly Enhunter 4.Explanation / Answer
1.
a. Saturated salt solution induce sol-gel transition in the aqueous solution of methylcellulose. Cellulose is naturally insoluble in aqueous solutions due to its own intra-hydrogen bonding. However, substitution of certain hydroxyl groups of cellulose by methyl group leads to its solubility in water and such derivative is called methylcellulose. Methylcellulose can able to form gel upon heating and gets solubalized upon cooling. It is temperature dependent process. This process is accelerated by using salt solution (eg., NaCl). This salt solution induces sol-gel transition at lower temperature.
b. This effect is known as salting-out. Its because, salt ions (Na+ and Cl- ) at particular ionic strength start interacting ith water molecules which leads to lowering of interaction between methyl cellulose and water. This leads to precipitation of methyl cellulose in the form of gel. Hence the name salting--out.
4. Tragacanth is highly branched heteropolysaccharide present in plant which is exploited for drug delivery applications. Hydroxyl units present in tragacanth can be used for modification and cross linking of the product. This tragacanth consists of two units: water soluble fraction known as tragacanthin and water swellable fraction known as bassorin. Hence swelling behavoiur is because of bassorin.
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