Separate to identify-chromatography
It is a technique used for separating mixtures and isolate substances. There are diverse types of
chromatography since substances have different polarities but have the same aim but different
stationary and mobile phase. In my assigment I will be focusing on 3 types of chromatographic
techniques: paper chromatography with plant pigments. Thin layer chromatography of extracted
plant pigments and paper chromatography with amino acids
Paper chromatography with extracted plant pigments
We used this to decide if a substance is impure or pure and to see which chemicals are present
Equipment and materials:
lab coat and eye protection to protect my skin
gloves to prevent irritation
pestle and mortar
propanone and sand
spinach
chromatography paper strips
capillary tubes
hairdryer
test tube
toothpick
pencil
Method
1.chop a small amount of spinach and place in a pestle and mortar. Grind with a few drops of
propanone and sand
2.collect your chromatography paper strips using a pencil so it does not dissolve in the solvent
3.use the capillary tube to transfer tiny drops of the extract to the bottom of the strip of the
chromatography paper
4. keep the spot diameter less than 2mm by using a ruler and dry the spot with a
hairdryer and repeat until the spot is a shade of dark green
5. add 1-2mm of running solvent to the test tube and wrap the top of the
chromatography paper strip around a toothpick and lower the strip into the test tube
without touching the sides. (This will take several minutes
6 once the solvent has reached the top of the strip, remove, and immediately use a
pencil to mark the solvent front
7. use a ruler to measure the distance run by the solvent front and by each pigment
8. calculate the Rf value and use it in a table
SOLVENT PEP/ETHER propanone pet
ether/propanone
Rf green 0.82 0.82 6.4
Rf yellow 1.4 0.3 1.9
Rf orange 0.1 N/A N/A
How does the paper chromatographic work
It separates mixtures to determine the components of the substance. The paper acts as a
solid that has small water molecules in the pores. These acts as the stationary phase
(remains on the chromatography paper and doesn’t move towards the paper) while the
Pep/Ether, propanone and pet ether/propanone acts as the mobile phase(the solvent
that moves upwards the paper as it dissolves the components which allows them to
, separate and be visible).
Advantages and disadvantages of paper chromatography
+simple
+low cost
+doesn’t use too much space
+it not hard to use
-complex mixtures can't be separated
-not useful for testing a large amount of samples
-data is not fully accurate
Thin layer chromatography
This technique works in a similar way to paper chromatography but instead of using
chromatography paper for stationary phase, it uses a silica embedded on a unreactive
surface. This means the compounds that hydrogen bond with the surface will be
absorbed on the surface
How does TLC work
with the solid stationary phases being present, the solutes are absorbed on the surface
of the solid particles. The relative force of attraction between the stationary, mobile
phases and the shows the separation happening
equipment/materials:
gloves
safety eye wear
lab coat
pre prepared sample of plant pigments
capillary tube
TLC strip
pencil
hairdryer
running solvent
TLC bottle
Method
1. use a pre-prepared sample of plant pigments to prevent centrifuging
2. collect the TLC without touching the surface of the plates
3.use a capillary tube to transfer small drops of the sample to the bottom of the TLC
strip and use a hairdryer between each addition. I did a few repeats until the spot is
dark green
4. add running solvent to the TLC bottle so that only the end where the spot is located is
in the solvent. I made sure not to let it touch the bottle sides
It is a technique used for separating mixtures and isolate substances. There are diverse types of
chromatography since substances have different polarities but have the same aim but different
stationary and mobile phase. In my assigment I will be focusing on 3 types of chromatographic
techniques: paper chromatography with plant pigments. Thin layer chromatography of extracted
plant pigments and paper chromatography with amino acids
Paper chromatography with extracted plant pigments
We used this to decide if a substance is impure or pure and to see which chemicals are present
Equipment and materials:
lab coat and eye protection to protect my skin
gloves to prevent irritation
pestle and mortar
propanone and sand
spinach
chromatography paper strips
capillary tubes
hairdryer
test tube
toothpick
pencil
Method
1.chop a small amount of spinach and place in a pestle and mortar. Grind with a few drops of
propanone and sand
2.collect your chromatography paper strips using a pencil so it does not dissolve in the solvent
3.use the capillary tube to transfer tiny drops of the extract to the bottom of the strip of the
chromatography paper
4. keep the spot diameter less than 2mm by using a ruler and dry the spot with a
hairdryer and repeat until the spot is a shade of dark green
5. add 1-2mm of running solvent to the test tube and wrap the top of the
chromatography paper strip around a toothpick and lower the strip into the test tube
without touching the sides. (This will take several minutes
6 once the solvent has reached the top of the strip, remove, and immediately use a
pencil to mark the solvent front
7. use a ruler to measure the distance run by the solvent front and by each pigment
8. calculate the Rf value and use it in a table
SOLVENT PEP/ETHER propanone pet
ether/propanone
Rf green 0.82 0.82 6.4
Rf yellow 1.4 0.3 1.9
Rf orange 0.1 N/A N/A
How does the paper chromatographic work
It separates mixtures to determine the components of the substance. The paper acts as a
solid that has small water molecules in the pores. These acts as the stationary phase
(remains on the chromatography paper and doesn’t move towards the paper) while the
Pep/Ether, propanone and pet ether/propanone acts as the mobile phase(the solvent
that moves upwards the paper as it dissolves the components which allows them to
, separate and be visible).
Advantages and disadvantages of paper chromatography
+simple
+low cost
+doesn’t use too much space
+it not hard to use
-complex mixtures can't be separated
-not useful for testing a large amount of samples
-data is not fully accurate
Thin layer chromatography
This technique works in a similar way to paper chromatography but instead of using
chromatography paper for stationary phase, it uses a silica embedded on a unreactive
surface. This means the compounds that hydrogen bond with the surface will be
absorbed on the surface
How does TLC work
with the solid stationary phases being present, the solutes are absorbed on the surface
of the solid particles. The relative force of attraction between the stationary, mobile
phases and the shows the separation happening
equipment/materials:
gloves
safety eye wear
lab coat
pre prepared sample of plant pigments
capillary tube
TLC strip
pencil
hairdryer
running solvent
TLC bottle
Method
1. use a pre-prepared sample of plant pigments to prevent centrifuging
2. collect the TLC without touching the surface of the plates
3.use a capillary tube to transfer small drops of the sample to the bottom of the TLC
strip and use a hairdryer between each addition. I did a few repeats until the spot is
dark green
4. add running solvent to the TLC bottle so that only the end where the spot is located is
in the solvent. I made sure not to let it touch the bottle sides
