15-01-2013, 11:01 AM
DETERMINATION OF CAFFINE IN TEA
[attachment=46918]
Introduction
Tea is the most common and widely used soft beverage in the household. It acts as a stimulant for central nervous system and skeletal muscles. That is why tea removes fatigue and headache. It also increases the capacity of thinking. Tea is also used for the lowering of body temperature. The principal constituent of tea, which is responsible for all these properties is the ALKALOID CAFFEINE. The amount of caffeine in tea leaves varies from sample to sample.
Originally it was thought hat caffeine is responsible for the taste and flavour of tea. But pure caffeine is tasteless white substance.
The xanthene beverages also create a medical problem. They are dietary of a stimulant of the CNS. Often the children are more susceptible than adults to excitation by xanthenes.
Theory
The most methylated alkaloid that occurs naturally is caffeine. Its molecular formula is CsH10N4O2. its IUPAC name is 1,3,7- trimethlyxanthene and common name is 1-methlylated thiobromine.
Purely, it is white, crystalline solid in the form of needles. Its melting point is 1230C. it is the main active principle components of tea leaves. It is present in tea leaves upto 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.
USES OF CAFFEINE
1) In medicine, it is used to stimulate, central nervous system and to increase flow of urine.
2) Because of its stimulating effects, caffeine has been used to relieve fatigue. But it is dangerous and one may collapse I not consumed in certain limits.
3) Caffeine is also used in analgesic tablets, as it is believed to be a pain killer. It is also beneficial in migraines.
EFFECTS OF CAFFEINE
1) it is psycho stimulant.
2) It proves physical and mental ability.
3) It effects in learning but intellectual performance may improve where it ahs been used to reduce fatigue or boredom.
4) When administered internally, it stimulates heart and nervous system and also acts as diuretic.
5) On the contrary their excessive use is harmful to digestion and their long use leads to mental retardation.
PROCEDURE
First of all, 50gms of tea leaves were taken as sample and 150ml of water was added to it in a beaker.
Then the beaker was heated upto extreme boiling.
The solution was filtered and lead acetae was added to the filtrate, leading to the formation of brown coloursed curdy 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 became 50ml.
Then the solution was allowed to cool.
After that, 20ml 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 weigh the residue and recorded the observations.
[attachment=46918]
Introduction
Tea is the most common and widely used soft beverage in the household. It acts as a stimulant for central nervous system and skeletal muscles. That is why tea removes fatigue and headache. It also increases the capacity of thinking. Tea is also used for the lowering of body temperature. The principal constituent of tea, which is responsible for all these properties is the ALKALOID CAFFEINE. The amount of caffeine in tea leaves varies from sample to sample.
Originally it was thought hat caffeine is responsible for the taste and flavour of tea. But pure caffeine is tasteless white substance.
The xanthene beverages also create a medical problem. They are dietary of a stimulant of the CNS. Often the children are more susceptible than adults to excitation by xanthenes.
Theory
The most methylated alkaloid that occurs naturally is caffeine. Its molecular formula is CsH10N4O2. its IUPAC name is 1,3,7- trimethlyxanthene and common name is 1-methlylated thiobromine.
Purely, it is white, crystalline solid in the form of needles. Its melting point is 1230C. it is the main active principle components of tea leaves. It is present in tea leaves upto 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.
USES OF CAFFEINE
1) In medicine, it is used to stimulate, central nervous system and to increase flow of urine.
2) Because of its stimulating effects, caffeine has been used to relieve fatigue. But it is dangerous and one may collapse I not consumed in certain limits.
3) Caffeine is also used in analgesic tablets, as it is believed to be a pain killer. It is also beneficial in migraines.
EFFECTS OF CAFFEINE
1) it is psycho stimulant.
2) It proves physical and mental ability.
3) It effects in learning but intellectual performance may improve where it ahs been used to reduce fatigue or boredom.
4) When administered internally, it stimulates heart and nervous system and also acts as diuretic.
5) On the contrary their excessive use is harmful to digestion and their long use leads to mental retardation.
PROCEDURE
First of all, 50gms of tea leaves were taken as sample and 150ml of water was added to it in a beaker.
Then the beaker was heated upto extreme boiling.
The solution was filtered and lead acetae was added to the filtrate, leading to the formation of brown coloursed curdy 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 became 50ml.
Then the solution was allowed to cool.
After that, 20ml 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 weigh the residue and recorded the observations.