Experiment 2
Title
Evaluation of the
effects of different amount of material on the characteristic of a suspension
formulation.
DATE OF EXPERIMENT: 18 MARCH 2013
Objectives
To study the effects that was produced by using different amount of Tragacanth in different suspension formulation.
Introduction
A suspension is a two
phased system in which a finely divided solid is dispersed in a continuous
phase of solid, liquid, or gas. The undissolved solid exists in equilibrium
with a saturated solution of the solid in the continuous phase. A
pharmaceutical suspension is a coarse dispersion in which insoluble solid
particles are dispersed in a liquid medium. Suspension is a coarse dispersion
in which internal phase is dispersed uniformly throughout the external phase.
The internal phase consisting of insoluble solid particles having a specific
range of size which is maintained uniformly throughout the suspending vehicle
with aid of single or combination of suspending agent.
A good suspension will
be suspended homogenously when it is shaken, ease in pouring, have uniform
particle size and have pleasant taste and texture. Sedimentation that is formed must
be easily re-dispersed and the dispersion formed must be homogenous.
Apparatus
Weighing balance 1
1ml pipette and pipette bulb
1 weighing boat 1
15 ml centrifuge tube
1 set of mortar and pestle 1
100ml beaker
1 150ml plastic bottle Centrifugator
1 50ml measuring cylinder Viscometer
1 200ml measuring cylinder
Materials
Chalk
Syrup BP
Tragacanth Double-strength
chloroform water
Concentrated peppermint water Distilled
water
Procedure
1. A formulation of Pediatric Chalk Mixture Suspension (150mL) were prepared using formula given.
Chalk 3g
Tragacanth Refer to table 1
Concentrated peppermint water 0.6ml
Syrup Bp 15ml
Double strength chloroform water 75ml
Distilled water, q.s 150ml
Pediatric Chalk
mixture
|
Group
|
Tragacanth(g)
|
I
|
1, 5,
|
0.0
|
II
|
2, 6
|
0.1
|
III
|
3, 7
|
0.3
|
IV
|
4, 8
|
0.5
|
2. 5mL of the suspension
were poured into a weighing boat and labeled. The texture, clarity, and colour
of suspension formed were explained and compared.
3. 50mL of the suspension
formed were poured into a 50mL measuring cylinder and the height of suspended
solid formed in the cylinder were recorded in intervals of 0, 5, 10, 15, 20,
25, 30, 40, 50 and 60 minutes.
4. The remaining 95mL of
the suspension were poured into a 100mL beaker and the viscosity of the
suspension were determined using Viscometer.
5. 10mL of suspension
were poured into a Centrifuge tube and the height of suspended phase were
determined.
1. Compare the physical
characteristics of the suspension formed and give explanation.
Table 1: Physical appearance of suspension
formed
Amount of tragacanth
(g)
|
Physical appereance
of suspension formed
|
0.0
|
Texture : Less viscous, rough
texture,redisperse easily
Clarity : Less cloudy, has 2 layers
Colour : Less milky
|
0.1
|
Texture :
Viscous
Clarity :
Moderate cloudy
Colour :
Milky
|
0.3
|
Texture :
Viscous
Clarity :
Opaque, Moderate cloudy
Colour :
Milky white
|
0.5
|
Texture : More viscous
Clarity : More cloudy
Colour : Milky
|
In
this part of experiment, we are comparing 4 suspensions containing different
amount of tragacanth powder. As shown in Table 1, suspension containing 0.5g of
tragacanth is the most viscous and most cloudy. When there is no tragacanth
added, the suspension has the least viscosity and cloudiness as well as
consists of two layer. It can be seen from the table, in any amount of
tragacanth, the suspension has a milky colour, resulted mainly from the
combination of colour of chalk and tragacanth.
Gum
tragacanth consists of two fractions, one soluble in water and other fraction
is water-insoluble.Tragacathin is
the water-soluble portion of tragacanth whereas Bassorin is the water-insoluble portion of the
tragacanth.Tragacanth contains about 15% of methoxy group which swells in
water.Due to the presence of methoxy group as a constituent of the gum,
tragacanth gum has high viscosity.When added to water, the soluble tragacanthin
dissolves to give a colloidal hydrosol solution, while the insoluble bassorin
component swells to a gel-like state. When added to water, the insoluble
bassorinpart of tragacanthables to swell in water to give thick, viscous
dispersions or pastes that is essential for many of its uses in the
pharmaceutical and food industries. Viscosity is the most important property of
the gum tragacanth solution. Therefore, increasing the amount of tragacanth
caused an increased in the viscosity of the suspension.
Chalk
particles are insoluble in pure water and will not be easily wetted. So, in
order to ensure adequate wetting, the interfacial tension between the solid and
the liquid must be reduced. Tragacanth is added to the suspension to help the
particles to disperse readily throughout the liquid. Tragcanth function as both
wetting agent and flocculating agent. As wetting agent, tragacanth will behave
as protective colloids by coating the solid hydrophobic particles with a
multi-molecular layer. This will impart a hydrophilic character to the solid
and so promote wetting.Flocculating agents decreases zeta potential of the suspended charged
particle and thus cause aggregation of the particles or formation of flocs.As flocculating agent, the tragacanth will
form a gel-like network within the system and become adsorbed on to the
surfaces of the dispersed particles, thus holding them in a flocculated state
for a longer period.
Besides
that, as mentioned earlier, tragacanth has a viscosity property that will
thicken the suspending medium, thereby reducing the sedimentation rate of the
suspended particles. The time taken for the particlesto settle increases and they remain
dispersed for longer time. The dispersed chalk particles in the flocculated
state are the one that contributes to the cloudiness of the suspension medium.
Hence, increasing the amount of tragacanth
caused an increased in the cloudiness of the suspension. When there is no
tragacanth added to the suspension medium, the insoluble chalk particles settle
to the bottom very rapidly. This explained the presence of two layers in the
suspension medium containing 0 g of tragacanth.
2. Plot a graph of
height of sediment vs. time. Give explanation.
Table 2: Results for Group A3
Time (min)
|
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
Height (mm)
|
0
|
3
|
5
|
7
|
8
|
9
|
9
|
9
|
10
|
10
|
10
|
10
|
10
|
The graph above shows the relationship between the heights of suspension
with time. For the first 25 minutes, the height of sedimentation increase with
increases the time. But when the time reached 30 minutes and 40 minutes the
height of suspension start to maintain for about 9mm and 10 mm respectively.
This is because all of the Tragacanth that is contain in the suspension already
sediment.
3. Plot a graph of
height of sediment vs. time for the formulation of suspension that contain
varied amount of Tragacanth. Give explanation.
Table 3: Results combined for Groups A1, A2, A3 and
A4.
Time (minute)
|
Height of the sediment (millimetre)
|
|||||||||||||
0
|
5
|
10
|
15
|
20
|
25
|
30
|
35
|
40
|
45
|
50
|
55
|
60
|
||
Amount of tragacanth
(g)
|
0.0
|
0
|
1
|
3
|
3
|
3
|
3
|
3
|
3
|
3
|
3
|
3
|
3
|
3
|
0.1
|
0
|
1
|
2
|
2.5
|
3
|
3
|
3
|
4
|
4
|
4
|
4
|
4
|
4
|
|
0.3
|
0
|
3
|
5
|
7
|
8
|
9
|
9
|
9
|
10
|
10
|
10
|
10
|
10
|
|
0.5
|
0
|
3
|
4
|
8
|
8
|
9
|
9
|
10
|
12
|
12
|
15
|
15
|
15
|
|
The graph above shows the relationship of the height of sedimentation
with time for four different suspensions that contain different amounts of
tragacanth. Tragacanth is the suspending agentsthat make the suspension become
more stable by reduce the sedimentation. A good suspension is a suspension that
the sedimentation process does not happen quickly when the suspension is
shaken. This is to allow that all the material in the suspension can disperse
for a longer time to increase the efficiency of suspension administration.
Based on the graph, it shows that height of sedimentation is increase
with increase in the amount of tragacanth. This is due to experimental error.
The absence of tragacanth(0.0 g of tragacanth) results in quick sedimentation
of solid particles and cause flocculation in suspension. For the suspension
which is containing 0.5 g amount of tragacanth, the sedimentation gradually
formed with an increase of height.
4. Briefly explain the
mechanism of analysis of viscometer. Plot a graph of the viscosity of the
suspension versus the content of Tragacanth. Give explanation.
Table 4.1: Tragacanth : 0.0 g (GroupA1)
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
2.5
|
1.5
|
1.5
|
1.0
|
2.0
|
2.5
|
Average ± SD
|
1.833 ± 0.606
|
|||||
Table 4.2: Tragacanth : 0.1 g (GroupA2)
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
5.0
|
5.0
|
5.0
|
5.0
|
5.0
|
5.0
|
Average ± SD
|
5.0 ± 0
|
|||||
Table 4.3: Tragacanth : 0.3 g (GroupA3)
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
0
|
0
|
6.0
|
6.0
|
12.0
|
12.0
|
Average ± SD
|
6 ± 5.367
|
|||||
Table 4.4: Tragacanth : 0.5g (GroupA4)
Reading
|
1
|
2
|
3
|
4
|
5
|
6
|
Viscosity (cP)
|
20
|
18.5
|
17.5
|
16.5
|
16.5
|
17
|
Average ± SD
|
17.667 ± 1.366
|
|||||
Table 4.5: Viscosity of the suspensions with
varying amount of tragacanth.
Amount of Tragacanth (g)
|
0.0
|
0.1
|
0.3
|
0.5
|
Viscosity (cP)
(average±SD)
|
1.833 ± 0.606
|
5.0 ± 0
|
6 ± 5.367
|
17.667 ± 1.366
|
Viscometer is used to measure and determine the viscosity of the fluid.
In this experiment, a rotational viscometer is used. When the rotating spindle
immersed in a sample fluid, the rotational viscometer uses the principle that the torque required to rotate a spindle at constant speed as a function of the
viscosity of that fluid. There are different types
of the spindle for different viscosity of sample fluid in order to gain an
accurate measurement. A thinner spindle is preferred for the analysis of a more
viscous suspension and vice versa.
A rotational viscometer typically consists of
one cylinder rotating inside another stationary cylinder. The gap in between
the two cylinders will be filled by the sample fluid in which it will resist
the rotation. Then the torque required to overcome the viscous resistance and
also to maintain the constant rotational rate is correlated with viscosity of
the sample. This measured data is then converted to a viscosity value and
output to the user. Thus it can be considered that the dynamic viscosity is proportional to
the measured torque. The standard rotational viscometer is common used for
measuring the viscosity of non-Newtonian fluids either in chemical or food
industries.
Tragacanth is a suspending agent, used to suspend the chalk powder in
suspension. It is also a thickener that can increase the viscosity of a suspension. In this experiment, the viscosity
of the suspension increases when the amount of
tragacanth incorporated increases. A more viscous suspension is considered a
more stable suspension. Formulation IV with the highest amount of
tragacanth(0.5g) recorded the highest reading of viscosity, which is 17.667cP.
Formulation I is the least viscous suspension with no tragacanth in the system
and a reading of 1.833cP. We can conclude that the viscosity of the suspension
prepared is proportional to the amount of suspending agent added.
In the experiment, some errors had been done and result in a high
standard derivation in the analysis. The curve shape of the graph of viscosity of
the suspension (cP) against amount of tragacanth (g) should be in a more gradual manner. This kind of errors maybe due to the
incorrect preparation of the susupension during the experiment. The amount of
the tragacanth should be accurately weighed. The operational procedure of the
viscometer shall be well understood before using it. The other manipulation of
the viscometer such as the speed of rotation should be constant for all the
four formulations as the speed may result in different measurement of the
viscosity.
5. Plot a graph of ratio of sediment height as a result of centrifugation vs.
weight of Tragacanth. Give explanation.
Tragacanth
content (g)
|
Height (mm)
|
|||
Before Centrifugation
|
After Centrifugation
|
Ratio of Height
|
||
0.0
|
Group 1
|
80
|
7
|
0.0875
|
0.1
|
Group 2
|
80
|
12
|
0.1500
|
0.3
|
Group 3
|
80
|
15
|
0.1923
|
0.5
|
Group 4
|
80
|
20
|
0.2500
|
Table 5: Ratio of sediment
height of the suspensions.
Tragacanth content (g)
|
0.0
|
0.1
|
0.3
|
0.5
|
Ratio of Height
|
0.0875
|
0.1500
|
0.1923
|
0.2500
|
Based
on the graph . ratio of height increased with the weight of the tragacanth.
This is because Height of sediment decrease slowly with weight of Tragacanth as
suspensions contain more Tragacanth is more stable.
6. What is the function of each material that is
used in the suspension formulation? How is the use of different amount of Tragacanth
affect the physical characteristic and stability of a suspension formulation?
- Chalk is used as an adsorbent. It also an active ingredient used in the treatment of diarrhea.
- Tragacanth is used as a suspending agent which form film around particle and decrease interparticle attraction. It also can acts as viscositing agent to increase in viscosity of the solution to prevent sedimentation.
- Concentrated Cinnamon Water is used as flavoring agent. Syrup BP is used as diluents and also sweetening agent.
- Double Strength Chloroform Water is used as preservative.
- Distilled water is used as vehicle.
The amount of
Tragacanth used will affect the physical properties of the suspension. Higher
amount of Tragacanth will produce smooth suspension. Suspension contain
Tragacanth is stable but on prolonged storage it is hard to redisperse. While
suspension without Tragacanth has low stability hence it will form
sedimentation rapidly but it is redisperse easily.
Conclusion
From this experiment , we know that the
stability and the physical characteristic of the suspension is affected by the
different amount of Tragacanth.
References
- Aulton, M.E. 2002. Pharmaceutics: The science of dosage form design. Edinburgh: Churchill Livingstone
- Banker, G.S. & Rhodes, C.T. 1990.Modern pharmaceutics.2nd Ed. New York: Marcel Dekker.
- Florence, A.T. & Attwood, D. 1998.Physico-chemical principles of pharmacy.3rd Ed. New York: Macmillan.
- http://www.kachabogums.com/gum-tragacanth.html
- http://naturalmedicines.hubpages.com/hub/gum-tragacanth
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