Objective
To
identify the content of ibuprofen whether it tally to the value stated
Apparatus
i)
Beaker 50 ml and 100 ml
ii)
Burette
iii)
Conical flask
iv)
Glass rod
v)
Hair dryer
vi)
Measuring cyclinder 100
ml and 10 ml
vii)
Electronic balance
viii)
Weighing boat
ix)
Filter funnel
Materials
i)
Ibuprofen tablets
ii)
Chloroform
iii)
Ethanol(96%)
iv)
0.1 M sodium hydroxide
v)
Phenolphthalein
Experimental Procedure
1.20
Ibuprofen tablets are previously
selected at random and weighed and are crushed into powder.
2. A quantity of powder containing 0.5g ibuprofen is extracted and mixed with 20ml
chloroform for 15 minutes.Then, it is filtered through a sintered glass crucible (BS Porosity No.1).
3. The residue is washed with 3 x 10ml chloroform and the combined filtrate is gently evaporated just to dryness in a current of air. The residue is dissolved in 100ml with ethanol (96%) that is previously neutralized to phenolphthalein solution.
4. The solution is then titrated with 0.1M sodium hydroxide to end point with phenolphthalein solution as the indicator. The content of ibuprofen is calculated if each ml of 0.1M sodium hydroxide is equivalent to 0.02063g of C13H18O2.
2. A quantity of powder containing 0.5g ibuprofen is extracted and mixed with 20ml
chloroform for 15 minutes.Then, it is filtered through a sintered glass crucible (BS Porosity No.1).
3. The residue is washed with 3 x 10ml chloroform and the combined filtrate is gently evaporated just to dryness in a current of air. The residue is dissolved in 100ml with ethanol (96%) that is previously neutralized to phenolphthalein solution.
4. The solution is then titrated with 0.1M sodium hydroxide to end point with phenolphthalein solution as the indicator. The content of ibuprofen is calculated if each ml of 0.1M sodium hydroxide is equivalent to 0.02063g of C13H18O2.
Results And Calculations
i)
1 tablet of Ibuprofen = 200mg
20 tablets of Ibuprofen = 20 x 200mg
= 4000mg(4g)
Mass of ibuprofen powder = 7.84 g
with diluents(20 tablets)
ii)
To obtain 0.5 g
ibuprofen active ingredient,the equation of total mass needed:
X= 7.84 x 0.5/4.0
= 0.98g
iii)
Mass of ibuprofen
powder weighed = 0.9803 g
Volume of NaOH used to reach end point = 21.1 ml
Number of mole of NaOH used,n = 2.11 x 10-3 mole
Molar mass of ibuprofen = 206.3 gmol-1
iv)
NaOH
|
C13H18O2
|
|
Mole
|
1x10-4
|
1x 10-4
|
Mole Ratio
|
1
|
1
|
v)
Given n = 2.11 x 10-3
Mass of ibuprofen react = 0.435 g
Standard deviation = 0.435/0.5 X 100
= 87 %
Discussion
Based on the result, the standard
deviation of the experiment is calculated
by using the formula below:
Standard deviation = (Experimental
value )/(Theoretical value) ×100%
= 0.435/0.5 × 100%
= 87 %
From the calculation, standard
deviation obtained is 87%. The standard deviation is within 85% to 115% which
is based on the range of the British Pharmacopoeia. Thus, the experimental
value is considered comply the test. The resulted deviation may be due to
several errors which occurred when the experiment was carried out. These errors
affect the accuracy of the experiment data.
Some
of the errors are the ibuprofen that used for the experiment may have expired
which causing the loss of active ingredients in the tablets as the active
ingredients might have decomposed. In order to increase the accuracy of the
experiment, ibuprofen tablets that are
not expired should be used.
Besides,
there also may be loss of the active
ingredients through the crushing process. When the tablets was crushing into the powder form
using mortar and pestle, some of them would drop out of the pestle, causing the
loss of ingredients. Thus, to prevent this to happen, the tablet should be
crush gently so that the loss of the active ingredient can be reduced.In addition,
over-titration would have occurred when carrying out titration with the sodium
hydroxide. This is due to the titration is too fast that we missed the volume
of sodium hydroxide that caused the first change of colour in the solution.
Thus, it would better that if the titration carried out slowly drop by drop
which will prevent from missing the
first end point of the titration.
Conclusion
The ibuprofen content obtained from
the experiment is 0.435g, which contributes to the standard deviation of the
experiment is 87%, complying the test of uniformity of content which is within
85% to 115%.
References
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