Chromatography- Assignment
Unit 2 Learning Aim C - Separate to identify assignment
Introduction
Chromatography is a technique for separating mixtures. This can be through the medium of
paper in paper chromatography or thin layer chromatography. This type of chromatography
uses a thin layer of cellulose or silica coated onto a plastic or glass sheet. Chromatography
works by different substances having different solubility is in different solvents.
Chromatography is an analytical technique because the substances are isolated, measured
and finally identified. The RF value or retention factor is calculated by the distance travelled
by the spot divided by the distance travelled by the solvent. (smallest/biggest) The RF value
cannot be higher than 1 this is because the spot cannot surpass the solvent front.
Chromatography allows us to separate mixtures into their individual substances. More
specifically, homogeneous mixtures can be separated by this method. Different solvents will
dissolve different substances. A polar solvent (water) will dissolve a polar substance (ink).
Chromatography is a form of purification, due to removing the impurities.
Paper chromatography- how it works
Paper chromatography works by passing the dissolved substance (amino acids, inks etc..)
through a filter paper, this is the stationary phase. Different substances have different
characteristics such as size and solubility. Solubility is a molecule’s ability to dissolve in a
particular solvent such as water and alcohol (ethanol). Because of these characteristics each
substance travels at a different speed, therefore, have different RF values. This is useful
because scientists can measure the RF value, and this can work out what a mixture is made
out off.
Principle of chromatography
Chromatography is based on the principle where molecules in mixture applied onto the surface or
into the solid, and fluid stationary phase is separating from each other while moving with the aid of a
mobile phase.
Positive Negative How it is useful to
scientists.
Paper Low cost Cannot Scientists can
chromatography Easy to separate study the RF value
complete the complex and identify what
experiment mixtures. component make-
Separation of Less accurate up it.
compounds in a Data cannot
short period of be saved for
time. a long period
Analysis of time.
requires a low The
amount of temperature
sample and humidity
, effect the
results.
Thin layer For accurate More It’s useful to
chromatography compared to expensive scientists to
paper Results from determine the
chromatography TLC are purity of the
More reliable difficult to substance.
Can separate reproduce.
more complex Temperature
mixtures. and humidity
can affect
the results.
(open
system)
Why are the techniques we used suitable for your experiments?
In our tests we used paper chromatography two test Spinach and kale. We used 4 ml of
propane for both substances to make it fair. Acetone was used to extract the leaf pigments
because propane is quite polar this is important plant pigments are usually quite polar
themselves so for example, they would not dissolve is Kerosene. Another reason why
Acetone was suitable for our experiments is that Acetone has a low boiling point (56
degrees C). This is useful for our experiments because it is easy to recover the plant
pigments. An alcohol such as propanol-2 would be a good solvent however it would be
harder to disinfect. The final reason of why Acetone is more suitable for our experiment is
that it is very cheap compared to other acids.
In our thin layer chromatography test, we used 2 ml of Butane. This is suitable for the
experiment due to it firstly being cheap another reason of why butene is suitable for our
experiment is because butane can be re-condensed without the use of extreme
temperatures, this is due to butane having a boiling point of -1 degrees This would make it
an effective solvent.
Aim
The objective of chromatography is to separate the various substances that make up a
mixture. Into individual substances. Once we have the individual substance, we can figure
out what the substances are that make up the mixer. We can do this by calculating the RF
value and compare the RF values to know RF values.
For our experiment, our aim was to find out how many types of chlorophyll a plant cell
contains. This is useful for a plant because they can absorb different types of wavelengths,
this is useful because the plant can maximise their photosynthesis capacity.
Method
Thin layer chromatography experiment
Products you would need to complete this experiment
, Pencil
Beaker cover
Stir rod
200ml Beaker
TLC Plate
Solvent(liquid)- acetone/propanone.
Sample (kale or spinach)
Method
1. Place 10ml of acetone solvent inside a 200ml beaker.
2. Cover the beaker so the solvent can saturate the air with vapour, this is to ensure
that it does not evaporate.
3. Draw a straight line on the TLC paper, so that is sits above the acetone solvent fill
line.
4. Using a stir rod, crush the kale sample to ensure that some sticks to the end of the
stir rod.
5. Apply the sample gathered on the end of the stir rod to the TLC pencil line
6. Place the TLC plate into the beaker and place the cover back on top to
prevent any evaporation.
7. Wait until the solvent has travelled up near to the top of the TLC plate edge, or a
sufficient distance (75%+).
8. Carefully take the TLC plate out and make sure you do not touch when the solvent
has been due to this would interfere with the results. Figure 1 shows TLC for
testing chloroplast
9. Mark the solvent front with a pencil.
10. Once removed, leave it to dry in a well-ventilated area or you could use a hair dryer
to speed up the progress.
11. After time this would hopefully revile one or more spots, which we can use to
calculate the RF values from them.
Paper Chromatography 2nd experiment
Products you will need to complete this experiment.
1. Paper chromatography (stationary phase)
2. paper clip
Unit 2 Learning Aim C - Separate to identify assignment
Introduction
Chromatography is a technique for separating mixtures. This can be through the medium of
paper in paper chromatography or thin layer chromatography. This type of chromatography
uses a thin layer of cellulose or silica coated onto a plastic or glass sheet. Chromatography
works by different substances having different solubility is in different solvents.
Chromatography is an analytical technique because the substances are isolated, measured
and finally identified. The RF value or retention factor is calculated by the distance travelled
by the spot divided by the distance travelled by the solvent. (smallest/biggest) The RF value
cannot be higher than 1 this is because the spot cannot surpass the solvent front.
Chromatography allows us to separate mixtures into their individual substances. More
specifically, homogeneous mixtures can be separated by this method. Different solvents will
dissolve different substances. A polar solvent (water) will dissolve a polar substance (ink).
Chromatography is a form of purification, due to removing the impurities.
Paper chromatography- how it works
Paper chromatography works by passing the dissolved substance (amino acids, inks etc..)
through a filter paper, this is the stationary phase. Different substances have different
characteristics such as size and solubility. Solubility is a molecule’s ability to dissolve in a
particular solvent such as water and alcohol (ethanol). Because of these characteristics each
substance travels at a different speed, therefore, have different RF values. This is useful
because scientists can measure the RF value, and this can work out what a mixture is made
out off.
Principle of chromatography
Chromatography is based on the principle where molecules in mixture applied onto the surface or
into the solid, and fluid stationary phase is separating from each other while moving with the aid of a
mobile phase.
Positive Negative How it is useful to
scientists.
Paper Low cost Cannot Scientists can
chromatography Easy to separate study the RF value
complete the complex and identify what
experiment mixtures. component make-
Separation of Less accurate up it.
compounds in a Data cannot
short period of be saved for
time. a long period
Analysis of time.
requires a low The
amount of temperature
sample and humidity
, effect the
results.
Thin layer For accurate More It’s useful to
chromatography compared to expensive scientists to
paper Results from determine the
chromatography TLC are purity of the
More reliable difficult to substance.
Can separate reproduce.
more complex Temperature
mixtures. and humidity
can affect
the results.
(open
system)
Why are the techniques we used suitable for your experiments?
In our tests we used paper chromatography two test Spinach and kale. We used 4 ml of
propane for both substances to make it fair. Acetone was used to extract the leaf pigments
because propane is quite polar this is important plant pigments are usually quite polar
themselves so for example, they would not dissolve is Kerosene. Another reason why
Acetone was suitable for our experiments is that Acetone has a low boiling point (56
degrees C). This is useful for our experiments because it is easy to recover the plant
pigments. An alcohol such as propanol-2 would be a good solvent however it would be
harder to disinfect. The final reason of why Acetone is more suitable for our experiment is
that it is very cheap compared to other acids.
In our thin layer chromatography test, we used 2 ml of Butane. This is suitable for the
experiment due to it firstly being cheap another reason of why butene is suitable for our
experiment is because butane can be re-condensed without the use of extreme
temperatures, this is due to butane having a boiling point of -1 degrees This would make it
an effective solvent.
Aim
The objective of chromatography is to separate the various substances that make up a
mixture. Into individual substances. Once we have the individual substance, we can figure
out what the substances are that make up the mixer. We can do this by calculating the RF
value and compare the RF values to know RF values.
For our experiment, our aim was to find out how many types of chlorophyll a plant cell
contains. This is useful for a plant because they can absorb different types of wavelengths,
this is useful because the plant can maximise their photosynthesis capacity.
Method
Thin layer chromatography experiment
Products you would need to complete this experiment
, Pencil
Beaker cover
Stir rod
200ml Beaker
TLC Plate
Solvent(liquid)- acetone/propanone.
Sample (kale or spinach)
Method
1. Place 10ml of acetone solvent inside a 200ml beaker.
2. Cover the beaker so the solvent can saturate the air with vapour, this is to ensure
that it does not evaporate.
3. Draw a straight line on the TLC paper, so that is sits above the acetone solvent fill
line.
4. Using a stir rod, crush the kale sample to ensure that some sticks to the end of the
stir rod.
5. Apply the sample gathered on the end of the stir rod to the TLC pencil line
6. Place the TLC plate into the beaker and place the cover back on top to
prevent any evaporation.
7. Wait until the solvent has travelled up near to the top of the TLC plate edge, or a
sufficient distance (75%+).
8. Carefully take the TLC plate out and make sure you do not touch when the solvent
has been due to this would interfere with the results. Figure 1 shows TLC for
testing chloroplast
9. Mark the solvent front with a pencil.
10. Once removed, leave it to dry in a well-ventilated area or you could use a hair dryer
to speed up the progress.
11. After time this would hopefully revile one or more spots, which we can use to
calculate the RF values from them.
Paper Chromatography 2nd experiment
Products you will need to complete this experiment.
1. Paper chromatography (stationary phase)
2. paper clip
