|
SIGNATURE |
EXPERIMENT NAME |
S.NO |
|
|
PHARMACEUTICAL PRE-FORMULATION |
01 |
|
|
PREPARATION OF DICLOFENAC SODIUM MICROEMULSION |
02 |
|
|
MICROENCAPSULATION PREPARATION OF POLY-E-CAPROLACTONE MICROSPHERE BY
SOLVENT EVAORATION METHOD |
03 |
|
|
PRINCIPLES OF GENETIC ENGINEERING |
04 |
|
|
PREPARATION OF LIQUID PARAFFIN& MAGNESIUM
HYDROXIDE EMULSION |
05 |
|
|
PREPARATION OF AMMONIUM CHLORIDE COUGH SYRUP |
06 |
|
|
PREPARATION OF COMPOUND SODIUM CHLORIDE MOUTH
WASH |
07 |
|
|
EVALUATION OF EFFECT OF LUBRICANTS ON
CONCENTRATION OF FLOW OF GRANULAR SAMPLE |
08 |
|
|
PREPARATION OF ZINC SULPHATE EYE DROP |
09 |
|
|
DETERMINITAION OF HARSNERS RATIO OF PROVIDED
SAMPLE |
10 |
|
|
PREPARATION OF PEDIATRIC DISPERSIBLE ASPIRIN
TABLETS |
11 |
|
|
DETERMINITION OF POROSITY OF HYDROGELS |
12 |
LAB-1
Pharmaceutical
Pre-formulation
Almost all drugs are marketed
as tablets, capsules or both. Prior to the development of these major dosage
forms, it is essential that pertain fundamental physical and chemical
properties of the drug molecule and other divided properties of the drug powder
are determined. This information decides many of the subsequent events and
approaches in formation development. This first learning phase is known as
preformulation.
Preformulation involves the
application of bio-pharmaceutical principles to the physicochemical parameters
of drug substance are characterized with the goal of designing optimum drug
delivery system.
Before beginning the formal
preformulation programs the preformulation scientist must consider the
following factors:
1.
The amount of drug available.
2.
The physicochemical properties of the drug already known.
3.
Therapeutic category and anticipated dose of compound.
4.
The nature of information, a formulation should have or would like to
have.
UV Spectroscopy
The first requirement of any
preformulation study is the development of a simple analytical method for
quantitative estimation in subsequent steps. Most of drugs have aromatic rings
and/or double bonds as part of their structure and absorb light in UV range.UV
spectroscopy being a fairly accurate and simple method is a performed
estimation technique at early preformulation stages. The absorption
Co-efficient of the drug can be determined by the formula:-
E =
AF / X
Where, A = Absorbance
F=
dilution factor
X
= weight of drug (mg)
It
is now possible to determine concentration of drug in any solution by measuring
absorbance.
C
= AF / E mg/ ml
Characterization of drug
molecules is very important step at the preformulation phase of product
development. Following studies are conducted as basic preformulation studies;
special studies are conducted depending on the type of dosage form and the type
of drug molecules.
1)
Solubility determination
2)
pKa determination
3)
Partition co-efficient
4)
Crystal properties and polymorphism
5)
Practical size, shape and surface area.
6)
Chemical stability profile.
Solubility Determination:
The solubility of drug is an
important physicochemical property because it affects the bioavailability of
the drug, the rate of drug release into dissolution medium and consequently,
the therapeutic efficiency of the pharmaceutical product.
The solubility of the molecules
in various solvents is determined as a first step. This information is valuable
is developing a formulation. Solubility is usually determined in variety of
commonly used solvents and some oils if the molecules are lipophilic.
The solubility of material is
usually determined by the equilibrium solubility method, which employs a
saturated solution of the material, obtained by stirring an excess of material
in the solvent for a prolonged until equilibrium achieved :-
Common solvents used for solubility
determination are:
|
1) |
Water |
8) |
Benzyl Alcohol |
|
2) |
Polyethylene Glycols |
9) |
Isopropyl Alcohol |
|
3) |
Propylene Glycol |
10) |
Tweens |
|
4) |
Glycerin |
11) |
Polysorbates |
|
5) |
Sorbitol |
12) |
Castor Oil |
|
6) |
Ethyl Alcohol |
13) |
Peanut Oil |
|
7) |
Methanol |
14) |
Sesame Oil |
Determination of the dissociation
content for a drug capable of ionization within a pH rang of 1 to 10 is
important since solubility and consequently absorption, can be altered by
orders of magnitude with changing pH. The Henderson – Hasseslebach equation
provides an estimate of the ionized and un-ionized drug concentration at a
particular pH.
For acidic compounds
pH = pKa + log (un-ionized drug / ionized drug)
For basic compounds
pH=pKa + log (ionized drug/unionized drug)
Partition Coefficient
Partition Coefficient (oil/
water) is a measure of a drug’s lipophilicity and an indication of its ability
to cross cell membranes. It is defined as the ratio of unionized drug
distributed between the organic and aqueous phases at equilibrium.
P o/w = (C oil / C water) equilibrium.
Since biological membranes are lipid in
nature. The rate of drug transfer for passively absorbed drugs is directly
related to the lipophilicity of the molecule. The partition coefficient is
commonly determined using an oil phase of octanol or chloroform and water.
Drugs having values if P much
greater than 1 are classified as
lipophilic, whereas those with
partition coefficient much less than 1
are indicative of a hydrophilic
drug.
Although it appears that the
partition coefficient may be the best
predictor of absorption rate,
the effect of dissolution rate,
pKa and solubility on
absorption must not be neglected.
Dissolution
The dissolution rate of a drug
is only important where it is the rate limiting step in the absorption process.
Kaplan suggested that provided the solubility of a drug exceeded to mg/ ml at
pH, 7 no bio-availability or distinction related problems were to be expected.
Below / mg/ ml such problems were quite possible and salt formation could
improve absorption and solubility by controlling the pH of the micro
environment, independently of the drug and dosage forms position within the GI
tract.
Crystal
Properties and Polymorphism
Many drug substances can exit
in more than one crystalline from with different space lattice arrangements.
This property is known as polymorphism. Polymorphs generally have different
melting points, x-ray diffraction patterns and solubility even though they are
chemically identical.
Differences in the dissolution
rates and solubility of different polymorphic forms of a given drug are very
commonly observed. When the absorption of a drug is dissolution rate limited, a
more soluble and faster-dissolving form may be utilized to improve the rate and
extent of bioavailability.
Selection of a polymorph that
is chemically more stable is a solution in many cases. Although a drug
substance may exist in two or more polymorphic forms, only one form is
thermodynamically stable at a given temperature and pressure. The other forms
would convert to the stable form with time. In general, the stable polymorph
exhibits the highest melting point, the lowest solubility, and the maximum
chemical stability. Various techniques are available for the investigation of
the solid state. These include microscopy (including hot stage microcopy),
infrared spectrophotometry, single-crystal x-ray and x-ray power diffraction,
thermal analysis, and dilatometry.
Particle Size, Shape and
Surface Area
In general, each new drug candidate should be
tested during Preformulation with the smallest particle size as is practical to
facilitate preparation of homogeneous samples and maximize the drug’ s surface
area for interactions.
Various chemical and physical
properties of drug substances are affected by their particle size distribution
and shapes. The effect is not only on the physical properties of solid drugs
but also, in some instances, on their biopharmaceutical behavior. It is
generally recognized that poorly soluble drugs showing a dissolution- rate
limiting step in the absorption process will be more readily bio available when
administered in a finely subdivided state rather than as a coarse material.
In case of tablets, size and
shape influence the flow and the mixing efficiency of powders and granules.
Size can also be a factor in stability: fine materials are relatively more open
to attack from atmospheric oxygen, the humidity, and interacting excipients
than are coarse materials.
-
Determination of particle size
-
Determination of surface area.
Particle size Determination
Though microscopy is the simplest
technique of estimating size ranges and shapes, it is to slow for quantitative
determination the material is best observed as a suspension in non-dissolving
fluid. Sieving
is
less useful technique at preformulation storage due to lack of bulk material.
But techniques like this are seldom used due to their tedious nature
instruments based on light scattering, (Royco), light blockage (HIAC) and
blockage of electrical conductivity path (coulter counter) are available.
Surface Area Determination
Surface area is most commonly
determined based on brunaver emette teller (BET) theory of adsorption. Most
substances adsorb a mono molecular layer of gas under certain conditions of
partial pressure of gas and temperature. Knowing the monolayer capacity of
adsorbent and the area of absorbable molecule, the surface area can be
calculated the adsorption process is carried out with nitrogen at-195 degree
Celsius at a partial pressure attainable when nitrogen is in a 30% temperature
with an inert gas (helium). The adsorption takes place by virtue of Vander
wal’s forces.
Power Flow Properties
When limited amounts of drugs
are available Power flow properties can be evaluated by measurements of bulk
density and angle of repose. Changes in particles size and shape are generally
very important an increase in crystal size or a more uniform shape will lead to
a small angle of repose and a smaller Carr’s index.
Chemical stability
profile
Preformulation stability
studies are usually the first quantitative assessment of chemical stability of
a new drug. These studies include both solution and solid state experiments
under condition typical for the handing, formulation, storage, and
administration of a drug candidate as well as stability in presence of other
recipients.
Factor effecting chemical
stability critical in rational dosage form design include temperature, pH and
dosage form diluents. The method of sterilization of potential product will be
largely dependent on the temperature stability of the drug. Drugs having
decreased stability at elevated temperatures cannot be sterilized by
autoclaving but must be sterilized by another means, e.g., filtration. The
effect of pH on drug stability is important in the development of both oral
administration & must be protected from the highly acidic environment of
the stomach. Buffer selection for potential dosage forms will be largely based
on the stability characteristic of the drug.
LAB-2
Preparation of Diclofenac Sodium Micro-emulsion
Theory:
Micro-emulsions are
specifically, optically, clear, isotropic and thermodynamically stable mixtures
of water, oil, surfactant with or without co-surfactants.
Unlike ordinary emulsions the particle
size of micro-emulsion is in the range nanometers, thus increasing the
absorption and bio-availability.
Formulation:
Castor
oil ______________________ 3.75 g
Propylene
glycol_________________ 5.65 g
Tween 80_______________________ 17.15g
Diclofenac sodium________________0.25 g
Phosphate buffer (pH 5.5)__________ 50 mL (q.s)
Preparation
of Phosphate buffer:
a)
Solution A:
Dissolve 13.16g of sodium dihydrogen
phosphate in water and make up the volume to 1000 mL.
b)
Solution B:
Dissolve 35.81 g of disodium hydrogen
phosphate in water and make up the volume upto 1000mL. Mix 94.6mL of Solution A
and 3.6mL of Solution B.
Preparation of Micro emulsion:
1. Dissolve diclofenac sodium in castor oil.
2. Dissolve PG and tween 80 in 23.15mL of phosphate buffer.
3. Heat oil aqueous phase separately to 50ͦ C.
4. Then add aqueous phase to oil
phase with stirring.
5. The homogeneous and stable
liquid emulsion will be formed spontaneously.
Now
make up the volume up-to 500mL with phosphate buffer.
LAB-3
MICROENCAPSULATION
INTRODUCTION
Micro-encapsulation is a process by which solids, liquids or
even gases may be
enclosed in microscopic particles formation of thin coatings
of wall material
around the substances''.
MATERIALS INVOLVED
IN MICROENCAPSULATION:
CORE MATERIAL:
The material to be coated .It may be liquid or solid .
Liquid core may be dissolved or dispersed material.
Composition of core
material:
Drug or active
constituent
Additive like
diluents
Stabilizers
Release rate
enhancers
COATING MATERIAL:
Inert substance which coats on core with desired thickness
E.g.
Gums: Gum arabic, sodium alginate,
Carbohydrates: Starch, dextran, sucrose
Celluloses: Carboxymethylcellulose,
methycellulose.
Lipids: Bees wax, stearic acid, phospholipids.
Proteins: Gelatin, albumin.
Microspheres are characteristically free flowing powders
consisting of protiens or
synthetic polymers which are biodegradable in nature and
ideally having
particle size less than 200 μm
The encapsulation efficiency of the microparticles or
micro-sphere or micro-capsule depends upon different factors like concentration
of the polymer, solubility of polymer in solvent, rate of solvent
removal,solubility of organic solvent in water.
MORPHOLOGY OF
MICROCAPSULES:
The morphology of microcapsules depends mainly on the core
material and the deposition
process of the shell.
1- Mononuclear (core-shell) microcapsules contain the shell
around the core.
2- Polynuclear capsules have many cores enclosed within the
shell.
3- Matrix encapsulation in which the core material is
distributed homogeneously into the
shell material.
In addition to these three basic morphologies, microcapsules
can also be mononuclear with
multiple shells, or they may form clusters of microcapsules.
Micro-encapsulation
techniques and the processes
1.Air suspension
2. Coacervation phase separation
3.Multiorifice-centrifugal process
4. Spray drying and congealing
5. Pan coating
6.Solvent evaporation techniques
7. Polymerization
1.Dispersing of solid, particulate core materials in a
supporting air stream 2.Spray coating on the air suspended particles. 3.Cyclic process is repeated, perhaps several hundred
times during processing, depending on the purpose of micro-encapsulation
the coating thickness. a. Formation of a three-immiscible chemical phases (a
liquid manufacturing phase, a core material phase and a coating material
phase). b. Deposition of the coating. c.Solidification of the coating
AIR SUSPENSION
COACERVATION & PHASE SEPARATIO
MULTIORIFICE-CENTRIFUGAL
PROCESS PAN
COATING
The coating is applied as a solution or as an atomized
spray to the desired solid core material in the coating pan. To remove the coating solvent, warm air is passed over
the coated materials as the coatings are being applied in the coating pans. A mechanical process for producing microcapsules that
utilizes centrifugal forces to hurl a core material particle through an
enveloping microencapsulation membrane thereby effecting mechanical
microencapsulation.
SPRAY DRYING AND
CONGEALING
Spray-drying Spray-chilling
a. Preparation of the dispersion a.
Preparation of the dispersion
b. Homogenization of the dispersion b. Homogenization
of the dispersion
c. Atomization of the infeed dispersiond. c. Atomization of the
infeed dispersion
d. Dehydration of the
atomized particles
SOLVENT
EVAPORATION
Solvent evaporation techniques are carried out in a liquid
manufacturing vehicle (O/W emulsion) which is prepared by agitation of two
immiscible liquids. The process involves dissolving microcapsule coating
(polymer) in a volatile solvent which is immiscible with the liquid
manufacturing vehicle phase. A core material (drug) to be microencapsulated is
dissolved or dispersed in the coating polymer solution. With agitation, the
core– coating material mixture is dispersed in the liquid manufacturing vehicle
phase to obtain appropriate size microcapsules.
POLYMERIZATION
A relatively new micro-encapsulation method utilizes
polymerization techniques to from protective micro-capsule coatings in situ.
The methods involve the reaction of monomeric units located at the interface
existing between a core material substance and a continuous phase in which the
core material is dispersed. The continuous or core material supporting phase is
usually a liquid or gas, and therefore the polymerization reaction occurs at a
liquid-liquid, liquid-gas, solid-liquid, or solid-gas interface.
PREPARATION OF PCL MICRO-SPHERES BY SOLVENT EVAPORATION
METHOD
Poly-ε-caprolactone (PCL) is a biodegradable, biocompatible and
semi crystalline,water insoluble
polymer having a very low glass transition
temperature.
Due to its slow degradation, PCL is
ideally suitable for extended drug
delivery system over a period time.
APPARATUS:
Beakers, Stirrer, Electronic/ magnetic
stirrer, Pipette, Funnel, Filter paper, Petri dish,Microscope
CHEMICALS:
Dichloromethane, Poly-ε-Caprolactone, Distilled water, Tween
80, n-hexane.
PRINCIPLE:
It is based on principle of solvent
evaporation.
PROCEDURE:
Beaker 1: Dissolve 4-5 crystals of
Poly- ε-Caprolactone in 5 ml
Dichloromethane and mix it well.
Beaker 2: Add 1gm of tween 80 in 50ml
distilled water and stir it for 15 min in stirrer.
·
Add drop wise Beaker
1 constituents into beaker 2 with continuous stirring.Stir for 1 hr.
·
After 1 hr filter the
turbid solution, add small amount of n-hexane & discard the filtrate and
dry the residue at room temperature (air dry).
·
Very fine
micro-spheres are obtained.
·
Store them in well
closed container.
·
Examine micro-spheres
under microscope to
determine their spherical shape.
ROLE OF INGREIDENTS:
l Dichloromethane: Organic solvent
l Poly-ε-Caprolactone:
Polymer
l Tween 80 : Surfactant
l n-hexane: For washing purpose
LAB-4
PRINCIPLES OF
GENETIC ENGINEERING
What is genetic engineering?
Genetic
engineering, also known as recombinant DNA technology, means altering the genes
in a living organism to produce a Genetically Modified Organism (GMO) with a
new genotype.
Various kinds
of genetic modification are possible:
1.inserting a
foreign gene from one species into another, forming a transgenic organism;
2.altering an
existing gene so that its product is changed; or
3.Changing gene
expression so that it is translated more often or not at all.
Basic steps in genetic engineering
^ Isolate the gene
^ Insert it in a host using a vector
^ Produce as many copies of the host
as possible
^ Separate and purify the product of
the gene
Step 1: Isolating the gene
Gene is cut out using restriction endonucleases (Molecular scissors)
Cut DNA at specific base sequence
DNA cut at exactly the right place to isolate the gene
Make a staggered cut, forming sticky ends
The cut ends are "sticky" because they have short stretches of
single-stranded DNA. These sticky ends will stick (or anneal) to another piece
of DNA by complementary base pairing, but only if they have both been cut with
the same restriction enzyme. Restriction enzymes are highly specific, and will
only cut DNA at specific base sequences, 4-8 base pairs long.
There are thousands of different restriction enzymes known, with over a
hundred different recognition sequences. Restriction enzymes are named after
the bacteria species they came from, so EcoR1 is from E. coli
strain R.
Step 2: Inserting gene into vector
•
Vector – molecule of
DNA which is used to carry a foreign gene into a host cell
Most common vectors are bacterial plasmids and phage viruses
– Plasmids – circular DNA
that present in bacteria, double stranded
A vector is needed because a length of DNA containing a gene on its own
won’t actually do
anything inside a host cell. Since it is not part of the cell’s normal genome
it won’t be replicated
when the cell divides, it won’t be expressed, and in fact it will
probably be broken down pretty quickly.
DNA fragments can be incorporated into a plasmid using restriction and
ligase enzymes. The restriction enzyme used here (PstI) cuts the plasmid
in the middle of one of the marker genes.
The foreign DNA anneals with the
plasmid and is joined covalently by DNA ligase to form a hybrid vector (in
other words a mixture or hybrid of bacterial and foreign DNA).
Step 3:
Inserting Vector Into Host
First of all, the host plasmids are removed for preparation for the
hosts to receive recombinant plasmids
Possible treatments that can help the hosts to take up the vectors
include; shocking, temperature shock, calcium ions – all help the
cells to uptake the plasmids
Not all bacteria will take up recombinant plasmids so they need to be
identified and isolated
These are needed to identify cells that have successfully taken up a
vector and so become transformed. With most of the techniques above less than
1% of the cells actually take up the vector, so a marker is needed to
distinguish these cells from all the others.
A common marker, used in plasmids, is a gene for resistance to an
antibiotic such as tetracycline. Bacterial cells taking up this plasmid are
resistant to this antibiotic. So if the cells are grown on a medium containing
tetracycline all the normal untransformed cells (99%) will die. Only the 1%
transformed cells will survive, and these can then be grown and cloned on
another plate.
Step 4:
Multiplication of the host cells by cloning
Large scale
fermenters by cloning
All genetically
identical because of asexual reproduction
Step 5:
Extraction of desired gene product
Cell lysis
Removal of debris
Purification
LAB-5
PREPARATION
OF LIQUID PARAFFIN& MAGNESIUM HYDROXIDE EMULSION
Official Formula:
Liquid paraffin =25ml
Chloroform spirit
=1.5ml
Magnesium Hydroxide Solution =Q.S
for 100 ml
Composition
of Magnesium Hydroxide Mixture :
Magnesium Sulfate =4.75gm
Sodium Hydroxide
=1.5gm
Light Magnesium Oxide
=5.25gm
Chloroform
=0.25ml
Distill Water =Q.S
100ml
Procedure:
1-Mix chloroform
spirit with 65 ml magnesium hydroxide mixture add liquid paraffin .
2-Mix thoroughly and then add remaining magnesium hydroxide mixture to
make the
volume up to 100 ml then pass this mixture through homogenizer to form
homogenize emulsion.
Uses:
Use
as Laxative &Antacid.
LAB-6
PREPARATION OF AMMONIUM CHLORIDE
COUGH SYRUP
Official Formula:
|
Ingredient |
Quantity |
|
Ammonium
Chloride |
28.3 gm |
|
Citric
Acid |
6.2 gm |
|
Chlorpheniramine |
0.4gm |
|
Sodium
benzoate |
2.2 gm |
|
Color
Raspberry Syrup |
0.91 ml |
|
Chloroform |
4.4ml |
|
Sugar |
6.67 gm |
|
Sodium
Sulphate |
0.5 ml |
|
Essence
raspberry |
6.5 gm |
|
Purified
Water |
1000 ml
(Q.S) |
|
Sodium
Citrate |
13.3 gm |
Procedure:
1. Dissolve
sugar in water by heating & then cool it at normal temperature
2. Add
ammonium chloride, Chlorpheniramine, Sodium citrate, Sodium Sulphate, Sodium
benzoate & Citric acid to it.
3. Dissolve
essence raspberry and color raspberry syrup separately and add to the aqueous
solution. Then make volume up to 1000ml with purified water.
Role Of Ingredients:
*Ammonium
Chloride as an active ingredient.
*Citric
Acid and Sodium Citrate as buffers.
*Chlorpheniramine
as an active ingredient.
*Sodium
benzoate as a preservative.
*Color
Raspberry Syrup as a coloring agent,
*Chloroform
as a solvent.
*Sugar as a
sweetener.
*Sodium
Sulphate as a stabilizing agent.
*Essence
raspberry as a flavoring agent.
LAB-7
PREPARATION OF COMPOUND SODIUM CHLORIDE MOUTH WASH
Official
formula:
Sodium bicarbonate 1gm
Sodium chloride 1.5gm
Conc. Peppermint oil emulsion 2.5ml
Double strength chloroform water 50ml
Water 100ml q.s
Procedure:
Dissolve sodium chloride and sodium bicarbonate in small
quantity of water. Then add peppermint oil emulsion with continuous stirring
after this add the double strength chloroform water and make the final volume
upto 100ml with distilled water.
Use:
Use as antiseptic.
LAB-8
EVALUATION OF THE EFFECT OF LUBRICANTS ON CONCENTRATION OF
FLOW OF GRANULAR SAMPLE
REQUIREMENTS:
Graduated cylinder
Power sample
Lubricants
PROCEDURE:
Prepare four samples of powders.
Use sample number one, a control having
no lubricant.
Sample number two contains 2%
lubricant.
In sample number three 4% lubricant is
added while in sample four 6% lubricant is added.
Then find compressibility index of
these samples.
FORMULA:
Compressibility index
= (1-V/V0)100
LAB-9
PREPARATION
OF ZINC SULPHATE EYE DROP
Requirements:
1) Zinc sulphate eye drop solution
2)Purified water etc
Official Formula :
Zinc sulphate =12.5
Sodium chloride =40mg
Solution for eye drop Q.S =5ML
Procedure :
1- Dissolve the weighed amount of zinc sulphate in purified water .
2-Then add eye drop solution to make the
volume 5 ml .
Formula For Eye Drop Solution:
Methyl Hdroxyl Benzoate =22mg
Proply Hydroxy Benzoate =11.4mg
Purified Water Q.S =100ml
Uses:
Antiseptic
Storage:
Store in close container.
Dosage:
1-2 drops
LAB-10
DETERMINATION OF
HARSNER’S RATIO OF PROVIDED POWDERED SAMPLE
Requirements:
*Powder sample
*Graduated cylinder
*Balance
Procedure:
*Take the powder and fill it up to the mark in
graduated cylinder.
*Then tap it gently on the table surface until the
volume is reduced to the constant level.
*Then take the powder of cylinder and then weigh it.
*Calculate the observations.
LAB-11
PREPARATION OF PEDIATRICS DISPERSIBLE
ASPIRIN TABLETS
Requirements:
75mg Aspirin
Citric Acid 7.5mg
Calcium Carbonate 25mg
Saccharin Sodium 0.75mg
Procedure:
Dry Granulation Method
Mix the weighed quantity of aspirin,
citric acid, calcium carbonate and saccharin sodium.
Then compress into slug using 13mm
flat punch
Grind the slung into small granules
Pass through the Mesh no.16 and then
compress it into tablet using tableting machine.
LAB-12
DETERMINATION OF POROSITY OF
HYDRO-GELS
Requirement:
Absolute ethanol, hydro gel disc and Petri dish.
Procedure:
Take the hydro gel and weigh it. Place it in the beaker containing
absolute ethanol for 24 hours. The disc will absorb the alcohol and swell up.
After 24 hours take out the disc, remove the extra alcohol by tissue paper.
Weigh it and measure the dimensions of swollen hydrogel and measure its
dimensions to determine the porosity by using the formula
Porosity = M2 –
M1 /ρV × 100
M1 = Initial weight
M2= Weight of swollen hydro gel
ρ= Density of absolute ethanol
V = Volume of swollen hydro gel
V= ρhr2
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