Provides holistic view and understanding of lab skills in unit 2. Fully referenced work explains multiple types of chromotography and lab reports.Distinction level work checked by mentors and professionals.
Separate to identify-Introduction to chromatography
As my job as a technical assistant at a chemical plant, many times the company is
often required to identify substances this is done by using the many types of
chromatography that help identify a substance and the pigments it's made from.
There are different types of chromatography and each one has it uses these types
include paper chromatography, TLC chromatography (Thin layer
chromatography), Gas chromatography and Ion exchange chromatography.
All(source2) these different types of chromatography have specific uses as paper
chromatography is used in pharmaceutical companies to determine their purity it
is also used in food and drinks in a lab chromatography is mainly used to analyse
reaction mixtures. Gas Chromatography is the process known for dividing the
chemical parts of a substance to determine the presence or absence of each
substance present and measuring the quantity of each substance. Gas
chromatography is used in industry for various reasons the main being to detect
any contaminants or additives in food products if this requirement is not met the
companies will no longer be able to meet their high standards. Ion exchange
chromatography is used to separate molecules such as proteins, amino acids and
nucleotides. Ion chromatography (source 3) is known to be used in water
chemistry analysis, ion chromatograms can measure the concentrations of ions
present such as sodium, potassium, magnesium and calcium. Ion chromatography
has many uses in industry from cleaning products to laboratory analysis to detect
different ions present. The different types of chromatography have many
advantages and disadvantages when compared to one another such as thin layer
chromatography is much quicker and more efficient than paper chromatograph
because it can give semi-quantitative results, its quicker than using paper
stationary phases. There are many types of mobile phases that can be used, they
are commonly detected using UV ligth,chemical spray or iodine. As well as thin
layer chromatography can be used for more substances unlike paper
chromatography an advantage of paper chromatography is that it can be easily
detected by the naked eye when separating water soluble compounds like inks.
However, it does have limited types of mobile phases that can be used which are
more prone to smearing. Both gas chromatography and ion chromatography are
used for different things each specific to its situations as a whole chromatography
,in general has many uses and is used in many industries such as food, chemical,
medicine, criminal investigation and many more.
Chromatography of Plant Leaves
This method is used to separate a mixture of different solutes. (Source 1) The
plant leaves used have a green colour this colour comes from the chlorophyll in
the plant which is the main product in photosynthesis when harvesting energy
from the sun. Leaves contain a lot of chlorophyll and other pigments which are
also present in the leafe and are visible on a chromatogram such as carotene,
anthocyanins and flavonoids.
Hypothesis-When the chromatography paper is placed into the beaker with
solvent. The different types of pigments will start to separate depending on their
rf value. Many pigments will be present such as Chlorophyll A and Carotene and
Xanthophyll. The rf values obtained can be compared to the reference (source 5)
literature values to see accuracy.
Equipment
Beaker
Chromatography Paper
Pencil
Green leaves
Propanol (solvent)
Pestel and mortar
Sand
Pippett
Capillary tube
Method
1-Use a few leaves and cut them up into small pieces, place them in the mortar at
about 2cm depth.
, 2-Add 6 drops of propanol using a pippet into the pestle and mortar and grind the
mixture properly, also add a pinch of sand.
3-Grind the leaves for 3 minutes.
4-On the chromatography paper draw a baseline using pencil 3cm from the
bottom of the paper.
5-Extract the liquid produced in the pestle and mortar using a capillary tube and
place a dot in the center of the baseline drawn. (Make sure to keep the spots
small as possible)
6-Alow the spot to dry and keep placing another spot repeat this five times, this
makes sure that one spot is heavily concentrated.
7-Add some propanol to the beaker and dip in the chromatogram make sure the
solvent is below the baseline drawn.
8- Leave the chromatogram in the beaker of solvent until it has travelled to the
top of the chromatogram
9- With a pencil mark how high the solvent has travelled and let the
chromatogram dry.
Risk Assessment
Scale for severity = 1 to 5
1-None
2- Negligible
3-Minor
4-Major
5-Fatal
Scale for likeyhood
1-Improbable
2-Remote
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