Extraction of caffeine from tea
Aim:To extract and determine caffine in various tea samples
Theory: Most popular drinks in India are “Tea and
Coffee” As is the popularity of these drinks so is the
contribution of India in their production. India has been the
leading producer of tea.
Tea grows indeed, fertile & well drained soil. It require
warm and moist climate throughout the year. Frequent
showers, well distributed over the year ensures continuous
growth of tender leaves. In India it grows mainly in low hills
of Assam, Hills of Darjeeling and Jalpaiguri, Northern West
Bengal and the hill of Nilgiri etc.
Tea also causes many harmful disease such as Diabetes,
problems in nervous system, decrease in ADN secretion
which causes increase in wine secretion and it has Nicotine
which is a Stimulant.
Components of Tea Leaves
► Cellulose – the major structural material of all plants
► Caffeine – one of the major water-soluble substances
present in tea leaves
► Tannins – high molecular weight, water-soluble compounds
that are responsible for the color of tea ► Flavonoid pigments
– a naturally occurring water-soluble phenolic compound
belonging to a large group that includes many plant pigments
► Chlorophyll – the green pigment in plants that captures the
light energy required for photosynthesis
Caffeine :
Systematic name: 1,3,7-trimethyl-1H- purine- 2,6(3H,7H)-dione
Other name: 1,3,7-trimethylxanthine 1,3,7-trimethyl-2,6-dioxopurine
Molecular formula: C8H10N4O2
Molecular mass: 194.19 g/mol
Melting point: 238°C
Solubility in water: slightly soluble
Highlighted Concepts Caffeine - increases the blood pressure
,stimulates the central nervous system ,promotes urine formation
,stimulates the action of the heart and lungs
Uses: - treats migraine ,increases the potency of analgesics ,relieves
asthma attacks
Percentage composition of solute caffeine = W1 / W2 x 100
Materials required: different tea samples(Double
Diamond ,Lipton Tiger, Red Label, Taj Mahal), distilled
water ,beaker, ,conical flask ,chloroform ,separating funnel,
Calcium Carbonate, HCl acid.
Procedure:
Extraction of Water Soluble Components from Tea
Sample - Step-I
1. Take about 100ml of distilled water in 250ml conical flask.
2. Add 5gm of tea and boil it for 4 to 5 minute. Then cool it
and filter.
3. Repeat this process again with 100ml of distilled water and
residual tea leave.
4. The filtrate in each case should be collected.
5. Now the wet tea samples may be dried in an over and
weighted.
Removal of Tannic Acid from Filtrate - Step-II
1. The filtrate obtained in the first step is now boiled with 2-3
grm. calcium carbonate to get tannic acid, present in tea
extract, frecipitated. On leaving it for ten minutes ppt. is
obtained.
2. Filter the solution without disturbing the ppt carefully. The
ppt should be transferred to filter paper only after all the
filtrate is removed.
3. Tannic acid has been extracted in the form of calcium
ternate which on treatment with hydrochloric acid give
tannic acid.
4. The filtrate is now free from tannic acid and can be used to
extract caffeine.
Extraction of Caffeine from Tannic Acid Free Filtrate -
Step-III
1. Take tannic acid filtrate obtained in step 2(ii) and add 100
ml of chloroform in it in a separating funnel and allow it to
stand for 10 minutes.
2. Again the same procedure as done in (i)
3. Mix if with the previous one.
4. From this chloroform extract, chloroform may be distilled
or evaporated.
The pale green residue obtained is crude caffeine. Repeat
this experiment with other brands of tea and record your
observation in a tabular form.
Weight of tea used = W1 grm.
Weight of Caffeine = W2 grm
Observation:
Sr.No. Name of Brand W1 W2 %age of
caffeine
1. Double 6gm 0.7 11.6
Diamond gm
2. Lipton Tiger 6gm 0.8 13.3
gm
3. Taj Mahal 6gm 0.7 11.6
gm
4. Red Label 6gm 0.72 12.0
gm
Experiment Results :
The tea sample of Double Diamond contain highest amount
of caffeine and hence :-
1. Gives better taste than others.
2. Is more harmful for our health.
Precautions and Expected Errors :
1. Chloroform should not be smelt directly for a long time as
it itself is toxic.
2. The measurement of weight of tea leaves and all extract
should be precise.
3. The measurement of weight of tea sample and all extract
should be precise.
4. The water used should be distilled.
5. Apparatus should be clean and dry.
6. No water should be added to any extract in between the
experiment as it may get errors in calculation.
7. No prolonged heating should be done as water may
evaporate in large quantity along with same volatile solutes.
Bibliography
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