deliquescence

Question 1

introduction

Answer 1

-it is derived from the latin word deliquecere literlly meaing “to start melting away”, from “liquere” that is “to be liquid”. So it mean, to dissolve gradually by absorbing moisture from the air
…….
-this process is reverse of efflorescence
-such substances are said to be deliquescent, and the process is termed is termed deliquescene.
-many pharmaceutical crystalline solid absrob water vapor readily from the enviroment and are considered to be hygroscopic
-uptake of unacceptable amount of water can cause effects on physical and chemical stability of the product:
phase transformation
chemical degradation
variation in disintegration
dissolution rate

Question 2

hygroscopic

Answer 2

a substance is hygroscopic if it reaily absorbs water from the atmosphere and forms a hydrate

Question 3

deliquescent

Answer 3

a substane is deliquescent if it abosrobs water from the air until it forms a solution

Question 4

definition

Answer 4

it is a phenomenon of taking up water vapor from the atmosphere when exposed to an atmosphere with higher partial pressure than the partial pressure of the substance to form a more hydrated liquid phase.

Question 5

deliquescent materials

Answer 5

-deliquescent materials are substances that have a strong affinity for moisture adn will abosrob relatively large amounts of water from the atmosphere if exposed to it forming a liquid solution
-calcium chloride
-magnesium chloride
-sodium hydroxide
-potassium hydroxie
-sodium lactate
-ferric ammonium citrate
-potassium bicarbonate

Question 6

process

Answer 6

-Water vapor from the air condenses on the surface of the solid and forms a very concentrated solution which has a vapor pressure much lower than the average vapor pressure of the water vapor in the air.
-The solution therefore continues to take up water until its vapor pressure equals the pressure of the water vapor in the air.
-CRH the deliquescent point is often termed as the critical relative humidity
-The critical relative humidity (CRH) of a salt is defined as the relative humidity of the surrounding atmosphere (at a certain temperature) at which the material begins to absorb moisture from the atmosphere and below which it will not absorb atmospheric moisture.
-below CRH, solids absorb minimal amounts of moisture at the surface
-above CRH, the solid starts dissolving in the condensate film
-The absorption process stops when vapor pressure of the resultant solution is equal to the vapor pressure of the atmosphere.
-If the vapor pressure is further increased, complete dissolution of the solid and solution dilution will ultimately occur

Question 7

disadvantages

Answer 7

-as in deliquescene water is picked up by the sample, unacceptable chanes in appearnce and performance occur
-chemical stabiity often changes dramatically
-physical impurites such as decrease in dissolution, variation in water content in the final product, crystallization of the formulation components and powder caking can occur
-chemical reaction such as hydrolysis and oxidation could also be accelerated by water sorption
-when excipients having relatively low CRH values are used they can affect the chemical and physical stability of a solid dosage form, even if the API’s CRH is not exceeded
-the liquid water can dissolve the API, making stability much worse
-Deliquescence lowering is independant of the ratio of the deliquescent components and therefore is of concern for any formulation containing two or more deliquescent compounds

Question 8

methods of prevent

Answer 8

-tight containers protect the contents from contamination by extraneous liquids, solid, or vapors, from loss from efflorescence, deliquescence or evaporation under ordinary and customary conditions of handling, shipment, storage, and distribution
-solid compounded frmulations, as inert powdered ingredient that will preferentially absorb water, maybe added to the formulation ex) light MgO

Question 9

storage precautions

Answer 9

-store the product is low humidity envormonet
-well closed containers should be used
-well filled container: limits the volume of the atmosphere in the container and therefore further reduces the uptake of moisture by the product
-a drying agent maybe placed inside the container ex) silica gel, often used in small packets

Question 10

application

Answer 10

-Owing to their very high affinity for water, these substances are often used as desiccants; these compounds are used in the chemical industry to remove the water produced by chemical reactions.
-Commonly used to protect against moisture damage.
-Used in hygroscopic cargo such as cocoa, coffee and various nuts and grains, that are particularly susceptible to mold and rot when exposed to condensation and humidity.
-These substances are used in the chemical industry to remove the water produced by chemical reactions to increase the yields.
-When spread in form of a powder or flakes, it absorbs more than its own weight of water and forms a liquid that keeps the road wet.
-Used in chemical industry to remove the water produced by chemical reactions to increase the yields.
-The property of deliquescence is utilized in the laboratory to dry substances; calcium chloride is often employed for this purpose