Index

!. Certification

2. Acknowledgement

3. Aim

4. Introduction

5. Theory

6. Apparatus & procedure

7. Observations

8. Conclusion

Certification

This is to certify that Sidrah Abbasi, a

student of class XII-B, has completed her

research successfully on the project title

“Determination of caffeine in different tea

samples” under the guidance of

Mrs.Bharti Ratan (Subject teacher) during

the year 2014-15 in partial fulfillment of

chemistry practical examination

conducted by AISSCE, New Delhi.

Signature of subject teacher

Acknowledgement

I would like take this opportunity to

thank my teacher, Mrs. Bharti Ratan,

whose support, guidance and

encouragement have enabled me to

complete this project. I would also like

to thank our lab assistant for his

cooperation.

Aim

“TO DETERMINE

THE AMOUNT OF

CAFFEINE

IN DIFFERENT TEA

SAMPLES”

Introduction

Caffeine is a central nervous system and

metabolic stimulant, and is used both

recreationally and medically to reduce physical

fatigue and to restore alertness when

drowsiness occurs. It produces increased

wakefulness, faster and clearer flow of

thought, increased focus, and better general

body coordination. The amount of caffeine

needed to produce effects varies from person

to person, depending on body size and degree

of tolerance. Effects begin less than an hour

after consumption, and a moderate dose

usually wears off in about five hours

Caffeine has a number of effects on sleep, but

does not affect all people in the same way. It

improves performance during sleep deprivation

but may lead to subsequent insomnia. In shift

workers it leads to fewer mistakes caused by

tiredness. In athletics, moderate doses of

caffeine can improve sprint, endurance, and

team sports performance, but the

improvements are usually not very large. Some

evidence suggests that coffee does not produce

the ergogenic effects observed in other caffeine

sources. High doses of caffeine, however, can

impair athletic performance by interfering

with coordination. There is also evidence that

caffeine may be helpful at high altitude.

Caffeine constitutes about 3% of tea's dry

weight.

Tea also contains small amounts

of theobromine and theophylline, which

are stimulants and xanthines similar to

caffeine.

Theory

The most important methylated alkaloid that

occurs naturally is caffeine. Its molecular

formula is CsH10N4O2. Its IUPAC name is 1, 3,

7-trimethylxanthene and common name is 1-

methylated thiobromine. Purely it is white,

crystalline solid in the form of needles. Its

melting point is 1230c. It is the main active

principle component of tea leaves. It is present

in tea leaves up to 3% and can be extracted by

first boiling the tea leaves with water which

dissolves many glycoside compounds in

addition to caffeine. The clear solution is then

treated with lead acetate to precipitate the

glycoside compounds in the form of lead

complex. The clear filtrate is then extracted

with extracts caffeine because it is more soluble

in it then water.

Effects of caffeine:

Positive effects

Acetylcholine is associated with attention,

concentration, learning, and memory but

there is no conclusive evidence yet that

caffeine has any effect on memory and

cognitive function.

Low doses of caffeine show increased

alertness and decreased fatigue.

Caffeine has been shown to increase the

metabolic rate.

Negative effects

Caffeine can increase blood pressure in

non-habitual consumers.

High blood pressure is associated with an

increase in strokes, and cerebral vascular

disease, which in turn increase the risk

of multi-infarct dementia.

Caffeine may reduce control of fine motor

movements (e.g. producing shaky hands)

Caffeine can increase cortisol secretion,

some tolerance is developed.

Caffeine can contribute to

increased insomnia and sleep latency.

Caffeine withdrawal can produce

headache, fatigue and decreased alertness.

High doses of caffeine (300 mg or higher)

can cause anxiety.

High caffeine consumption accelerates bone

loss at the spine in elderly postmenopausal

women.

Apparatus

Green label tea, yellow label tea, red

label tea, lead acetate, chloroform,

beakers, glass rod, filter paper, funnel,

water

Procedure

First of all, 50 grams of tea leaves

were taken as sample and 150 ml of

water was added to it in a beaker.

Then the beaker was heated up to

extreme boiling.

The solution was filtered and lead

acetate was added to the filtrater,

leading to the formation of a curdy

brown coloured precipitate.

We kept on adding lead acetate till no

more precipitate has been formed.

Again solution was filtered.

Now the filtrate so obtained was

heated until it had become 50 ml.

Then the solution left was allowed to

cool.

After that, 20 ml. of chloroform was

added to it.

Soon after, two layers appeared in the

separating funnel.

We separated the lower layer.

The solution then exposed to

atmosphere in order to allow

chloroform to get evaporated.

The residue left behind was caffeine.

Then we weighed it and recorded the

observations.

Similar procedure was performed with

different samples of tealeaves and

quantity of caffeine was observed in

them.

Observations

I. Red Label Tea (Brooke Bond)

Weight of china dish - 46.60gms

Weight of china dish with precipitate -

47.20gms.

Amount of caffeine - 0.60gms

2. Yellow Label Tea (Lipton)

Weight of china dish - 46.60gms

Weight of china dish with precipitate -

47.15gms.

Amount of caffeine - 0.55gms

3. Green Label Tea (Lipton)

Weight of china dish - 46.60gms.

Weight of china dish with precipitate -

47.05gms.

Amount of caffeine - 0.45gms.

Conclusion

Order of quantities of caffeine in different samples of

tea leaves:

Red label tea> Yellow label tea> Green label tea

600mg 550mg 450mg

Red label tea Yellow label tea Green label tea