1) Muhammad Syakir Bin Mohd Shahrizan (A162715)
2) Akmal Hadawiah Binti Ismail Yatim (A162694)
3) Koo Bao Yi (A162843)
Suspension is a mixture in which small particles of a
substance are dispersed throughout a gas or liquid. If a suspension is left
undisturbed, the particles are likely to settle to the bottom. It consists of
two phases in a heterogeneous system namely distribution phase and continuous
phase. Distribution phase is made up of particulate matter which is essentially
insoluble in, but dispersed throughout, the continuous phase while continuous
phase is generally the external phase that is made of a liquid or a semi-solid.
A good suspension should have the
following properties such as must be homogenously dispersed when shaken,
pourable, pleasant taste and texture and also uniform particle size. Besides,
they should also be ease of re-dispersion of settled solid particles,
physically and chemically stable and resistant against microbial contamination.
The dispersion of the solid particles is always associate with the disadvantage
of using suspension as it will contribute to the lack of uniformity of dose. In
order to overcome this problem, a careful formulation and other proper steps
need to be done such as shaking the formulation before used. This is where
wetting agents play an important role which act as a helper to decrease the rate
of settling and to permit easy re-suspension of any settled particulate matter.
Wetting agents such as tragacanth which is commonly used can assist in this
process by reducing the surface tension thus making it easier for the solid
particles in the suspension to redisperse. The amount of wetting agent used in
any given formulation depends on the volume of vehicle being thickened. It does
not vary with the amount of powder in the preparation. A wetting agent is
intended to increase the viscosity of the vehicle and therefore slow down
sedimentation rates.
OBJECTIVE
To
study the effect of different amount of tragacanth on the sedimentation rate of
suspensions.
APPARATUS
1
mL graduated pipette 100 mL beaker
Pipettle
bulb Parafilm
Weighing
boat
Weighing balance
Mortar
and pestle
Viscometer
50mL
graduated cylinder
200 mL graduated cylinder
MATERIALS
MATERIALS
Chalk
Double strength chloroform water
Tragacanth
Distilled water
Concentrated
peppermint water
Syrup BP
PROCEDURE
1. A suspension of Pediatric Chalk Mixture
(150 mL) is prepared according to the following formula
Ingredient
|
Suspension
|
|||
A
|
B
|
C
|
D
|
|
Chalk (g)
|
3
|
3
|
3
|
-
|
Tragacanth (g)
|
0.0
|
0.03
|
0.05
|
0.1
|
Concentrated peppermint water (mL)
|
0.5
|
0.5
|
0.5
|
0.5
|
Syrup BP (mL)
|
15
|
15
|
15
|
15
|
Double Strength Chloroform water (mL)
|
75
|
75
|
75
|
75
|
Distilled water q.s. (mL)
|
150
|
150
|
150
|
150
|
2. 5
mL of the suspension is poured into a weighing boat and each formulation is
labelled. The texture, clarity and colour of each suspension are observed and
compared.
3. The
sedimentation rate of each suspension is determined. The suspension is shaken
vigorously making sure all of the particles are uniformly suspended, and the
time is noted.
4. The
gradated cylinder is set down on the lab bench and the lab timer is started at
this point.
5. For
suspensions A to D, the sedimentation volume of the suspensions at t= 0, 2, 5,
10, 15 and 30 min are recorded.
6. The
sedimentation volume ratio is calculated using the following formula:
Sedimentation
volume ratio = Hu/ Ho
Hu: ultimate
height of the sediment, i.e the height of the sediment at a particular time
Ho: initial height
of the total suspension
7. The
ease of re-dispersibility of each formulation is examined after the last
measurement.
8. The
parafilm is snug on the mouth of the graduated cylinder and the seal is
re-enforced with gloved hand.
9. The
number of inversions it takes to completely re-disperse the drug is counted and
the observations are recorded.
10. 50
mL of suspension is poured into a 100 mL beaker and the viscosity of the suspension
is determined by using viscometer at 100 rpm for 30 seconds.
11. Each
suspension is poured into a plastic bottle. The ease of re-dispersion in each
system is determined after storing all the suspensions for a period of 4 days.
The most acceptable system is determined.
RESULT
Suspension
|
Distinct Boundary (Yes/No)
|
Sedimentation volume at pre-determined
time (min)
|
|||||
0
|
2
|
5
|
10
|
15
|
30
|
||
A
|
Yes
|
0
|
0.4
|
0.7
|
1.0
|
0.8
|
0.8
|
B
|
Yes
|
0
|
0.2
|
0.4
|
0.5
|
0.6
|
0.7
|
C
|
Yes
|
0
|
0.1
|
0.2
|
0.3
|
0.3
|
0.5
|
D
|
No
|
0
|
0
|
0
|
0
|
0
|
0
|
Sedimentation volume ratio = Hu/Ho
Suspension
|
Sedimentation volume ratio (Hu/Ho)
|
|||||
0
|
2
|
5
|
10
|
15
|
30
|
|
A
|
0
|
0.041
|
0.072
|
0.103
|
0.082
|
0.082
|
B
|
0
|
0.021
|
0.041
|
0.052
|
0.062
|
0.072
|
C
|
0
|
0.010
|
0.021
|
0.031
|
0.031
|
0.052
|
D
|
0
|
0
|
0
|
0
|
0
|
0
|
Table
1
Suspension
|
A
|
B
|
C
|
D
|
|
Viscosity
|
First
|
0.21
|
0.23
|
0.27
|
0.40
|
Second
|
0.23
|
0.22
|
0.32
|
0.42
|
|
Third
|
0.32
|
0.32
|
0.30
|
0.36
|
|
Mean
|
0.25
|
0.26
|
0.30
|
0.39
|
|
SD
|
0.048
|
0.045
|
0.021
|
0.025
|
|
Table 2
DISCUSSION
1. Compare and discuss physical appearances of all the
suspensions produced.
Suspension
|
Physical Appearances
|
||
Texture
|
Clarity
|
Color
|
|
A
|
Watery,
less viscous, easy to sediment
|
Moderate
cloudy
|
White
|
B
|
Viscous,
not easy to form sediment
|
More
cloudy
|
White
|
C
|
Viscous,
not easy to form sediment
|
Cloudiest
|
White
|
D
|
The
most viscous, no sedimentation
|
Clear
|
Clear
|
For the texture,
suspension D is the most viscous compared to other suspension since suspension
D contains the highest amount of tragacanth compared to others which is 0.1g. Adding
of tragacanth will increase the viscosity of the suspension. Thus, higher
amount of tracaganth added, the higher the viscosity of the suspension. The higher the viscosity, the harder for the
suspension to be disperse. For the clarity, suspension C appears to be the cloudiest
among all suspension because the solid chalk particles are fully dispersed. In
suspension D, it appears to be clear and no sedimentation because no chalk is
present.
2. Plot Hu/Ho vs. time for each of the suspensions
(Table 1). Discuss the findings.
Based on the graph, the
sedimentation volume ratio will increase as the time increase. Suspension A
shows high sedimentation volume ratio compare to other suspensions. This is
because suspension A does not contain tragacanth which acts as the suspending
agent to help the chalk to disperse throughout the suspension. Thus, a lot of
insoluble chalk powder sediment accumulated at the bottom of the suspension
over a period of time. In the beginning, chalk particles sediment quickly
because the suspension has less viscosity. However, after more and more chalk
particles sediment at the bottom, the particles begin to compress each other
and filled up the spaces in between. So, the height of the sediment reduced.
This can be seen from the graph, where the sedimentation volume ratio starts to
decrease after 10 minutes.
For
suspension B, the sedimentation volume ratio is lower than suspension A due to
the presence of tragacanth which helps the chalk particles to disperse
throughout the suspension. The chalk particles sediment slower because the
suspension more viscous. For suspension C, the sedimentation volume ratio is
even lower compared to A and B because the amount of tragacanth added is
higher. So, the viscosity of the suspension is higher. Therefore, the chalk
particles sedimentation is slower than others. The sedimentation in the
suspensions occurs due to gravitational force. However, the sedimentation rate
varies because of the different viscosity in each suspension where it affects
the times taken for the particles to sediment.
Suspension
D shows sedimentation volume ratio of 0 even though the amount of tracaganth
added is the highest. This is because there is no chalk is added to the
suspension hence no sediment is observed.
3.
Briefly explain the principle of analysis using viscometer. Plot the viscosity
vs tragacanth content. Discuss the findings.
Viscosity is measured in Pascal
seconds (Pa·s), in other words, the amount of pressure needed to achieve a
given rate of flow. Viscosity is commonly stated in centipoise (cP), which is
the standard unit used. It is measured using viscometer by physics’ principle.
A brief explanation of the principle of analysis using viscometer is a type of
force which is known as torque. Torque is a measure of the force that can cause
an object to rotate about an axis. By using a rotational viscometer, it allows a
torsion spring to measure the torque required to rotate a spindle in the
material. The spindle is immersed in the fluid or material that we want to
analyze. A correct type of spindle, the speed and time taken are important
aspects that are need to be considered. Changing rotor speed and size allows
for the measurement of different ranges of viscosity. In this experiment, the
type of spindle used was type 1 with the speed of 100 rpm in 30 seconds.
From the graph, it can be seen that
the viscosity is increasing when the amount of tragacanth increases. Tragacanth
is used as wetting agent in which it decreases the surface tension, allow it to
spread drops onto a surface and makes the suspension more viscous. Increasing
the viscosity will also help to reduce the sedimentation rate of the suspension
thus increasing the stability of the suspension. In conclusion, the viscosity
is directly proportional to the amount of tragacanth.
4.
After storing the suspensions for a period of 4 days, determine the ease of
redispersion of each.
The easiest suspension to be
redispersed is A is followed by B, C, and D. It is because the difference in
the viscosity. Suspension A is the easiest to be redispersed because it has low
viscosity. Only small amount of force is required to redisperse it. A simple
shaking can easily redisperse the suspension. On the other hand, suspension D
is the hardest to redisperse. This is because suspension D has the highest viscosity
due to the highest amount of tragacanth. Viscosity hinders the dispersion of
the insoluble particles. The suspension with higher amount of suspending agent
takes longer time to be redispersed. High viscosity is not totally beneficial
in suspension because of the difficulty in redispersing the suspension once it
sediments. This will cause unequal and inaccurate dosing when taking the
suspension.
5. Based on all the observations, which
products would be considered to be most acceptable? Explain.
Based on all observations, suspension C would be
considered to be the most acceptable. It is because it contains appropriate
amount of suspending agent which is tragacanth. In term of sedimentation rate,
suspension C gets to sediment slower, whereby the particle is uniformly
dispersed which makes it more stable. Suspension C is easier to be redisperse
and has suitable viscosity. Thus, suspension C is the most acceptable.
6.
Briefly explain all function of each excipients used in suspension formulation.
Explain the influence of tragacanth on the physical characteristic and
stability of suspension.
The active ingredient in this formulation is chalk.
Chalk function as an absorbent to absorb excessive fluids in watery feces, it
is used to treat diarrhea. Adding tragacanth will help the chalk to disperse
throughout the suspension by decreasing the interfacial tension between the
solid chalk particles and the external aqueous phase. Tragacanth is a wetting
agent and suspending agent, it also increases the viscosity of the medium and prevent
sedimentation of the suspended particle. Concentrated peppermint powder use as
flavouring agent which able to mask unpleasant taste of drug. Syrup BP act as
sweetening agent and also helps in increasing the viscosity of the suspension.
Double strength of chloroform water act as preservative and distilled water are
used to dilute the suspension.
Tragacanth influence physical characteristic of suspension
by increasing its viscosity and thus making it appears milky and cloudy. The
cloudiness of suspension although may not be appealing, but it indicates the
solid chalk particles are fully dispersed in the medium, and this is a good
suspension which will provide uniform dose. If no tragacanth is added, the
suspension will appears as two distinct layers, the chalk particles that
supposed to be dispersed is sediment at the bottom of the container. Stability
of suspension also depends on the amount of tragacanth used. Tragacanth act as
suspending agent and thickening agent in suspension formulation. When the
amount of tragacanth increase, suspension will become more viscous, rate of
sedimentation of particle become slow and remain disperse for a longer period
in suspension, hence, stability of suspension will increase.
CONCLUSION
Followed
by the result, we can conclude that the trend is less surfactant , easier to
redisperse . Viscosity of suspension is important in order to determine
sedimentation rate . The suspension easily got separate when we decrease amount
of tragacanth (suspending agent) .
REFERENCE
1.
Michael E.Aulton, Aulton’s Pharmaceutics The Design And Manufacture of
Medicines, third edition, 2007, Churchill Livingstone Elsevier
No comments:
Post a Comment