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Essay Unit 2C
- Module
- Unit 2C
- Institution
- PEARSON (PEARSON)
Providing an in-depth and detailed coursework of applied science. Unit 2C describes the practical and procedure of TCL and Paper Chromatography
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Tanya HussainUNIT 2C: PRACTICAL SCIENTIFIC PROCEDURES AND TECHNIQUES
TLC AND PAPER CHROMATOGRAPHY
AIM:To undertake chromatographic techniques to identify components in mixtures
SCENARIO: I am a newly hired technical assistant at Chemcalequip, a large chemical facility. In order to move
forward in my work and as part of my induction phase, I must show that I am capable of a variety of practical
processes and approaches. I must be able to demonstrate that I can use various chromatographic techniques to
separate and identify components in mixtures because the company frequently needs to identify compounds.
INTRODUCTION: Using a thin stationary phase supported by an inert backing, thin layer chromatography (TLC) is
a chromatographic technique used to separate the components of a mixture. It can be carried out on an analytical
scale to track the development of a reaction or on a preparative scale to purify minute quantities of a chemical.
Because of its simplicity, comparatively low cost, great sensitivity, and rapid separation, TLC is an extensively
used analytical method. Similar to all chromatography, TLC works on the premise that a chemical will have
varying affinities for the mobile and stationary phases, which will influence how quickly it migrates. TLC aims to
produce well-defined, well-separated spots.
USES: Smaller investigations that call for examining liquid or solvent compounds, the quantity of components, or
the purity of compounds in a mixture are best suited for thin-layer chromatography. The most common industries
that use this method include: Food Chemistry, Agriculture (mostly for pesticide analysis), Toxicology,
Pharmaceuticals
WHAT IS THE PROCESS OF CHROMATOGRAPHY?
The mixture of different soluble liquids that we must separate is the solute. They could be polar or nonpolar
solutes. The bottom of the paper is placed into the solvent once the solute is on the chromatography paper or
plate. The individual components are separated along as the solvent passes through the paper. The stationary
phase is a substance that does not move, and the mobile phase is a solvent that moves through the paper. The
forces between the solute and solvent that pull the solute up the stationary phase are the principal
intermolecular forces at work throughout the chromatography process. The mixture's molecules or ions will
adsorb to the surface of the stationary phase due to the solute molecules' adsorption into the stationary phase.
The solvent will move higher if the intermolecular forces between the molecules of the solute and the solvent are
larger than the forces between the molecules of the solute and the stationary phase, causing the Rf value to
increase. The stationary phase will be absorbed by the solute. The size of the molecules is one of the variables
that affects chromatography.
The amount of solubility of the material depends on the size of the molecule. Temperature is a crucial factor in
solubility since it will make the molecules of the solute lose their ability to form strong bonds because they will
have more kinetic energy. This will make the substances more soluble.
,The size of the molecule is also a factor in mobility because they typically have less mass, smaller molecules will
move farther. The polarity of the components involved, including the solute, solvent, and maybe the stationary
phase, has an impact on chromatography as well. Because polar molecules have little electrical charge, they are
drawn to one another. Polar molecules will not absorb as much into a polar solvent and will instead be transported
further up the stationary phase by the solvent. The nonpolar mobile phase will move non-polar molecules higher
up the plate.
FACTORS AFFECTING CHROMATOGRAPHY: A factor that affects chromatography is the size of the particle in
the stationary phase. When the particle size is small, it increases the surface area. This is because more of the
particles that make up the substance will be exposed on the surface which improves the separation and the flow
rate of the mobile phase decreases. The smaller particles move up the plate more faster than bigger particles.
The polarity of the molecules can affect how far the spots travel. They are more strongly attracted to the polar
solvent rather than a non polar solvent. Another factor is temperature, as the temperature increases the elution is
sped up as the adsorption is reduced at higher temperatures. Solubility is another factor because the higher the
solubility in the mobile phase, the faster the components will elute out of the chromatography stationary phase.
THE USES OF CHROMATOGRAPHY WITHIN THE INDUSTRY
Chromatography is crucial to the security of medications. Chromatography is used by pharmaceutical businesses
to quantify and examine substances for impurities. For instance, chiral substances have two distinct forms as a
result of the large variations of their atoms. There is evidence that some chiral chemicals can be harmful. The
safe version of the chiral chemical can be distinguished from the harmful form using chromatography.
Chromatography is also used in the production of vaccines.
The most effective antibodies for battling and neutralising particular diseases can be identified through
chromatography. Liquid chromatography has completely changed clinical laboratory testing, working in
collaboration with mass spectrometry. Even though mass spectrometry can identify analytes by their precursor
and production masses. There are numerous ways to use chromatography within the industry, some common uses
are:
MEDICAL AND PHARMACEUTICAL INDUSTRIES: Chromatography is used in the pharmaceutical and medical
sectors to make vaccines. Which antibodies are most effective at warding off sickness and viruses can be
determined via chromatography.
FOOD PROCESSING AND TESTING: Food firms can identify the ingredients in food using chromatography.
Proteins, vitamins, preservatives, and other nutrients are all analysed by companies before being added to
products. They can check the nutritional value of their products utilising chromatography.
DRINK AND BEVERAGE TESTING: Chromatography can be used to implement quality control in the food and
beverage industry. Chromatography is a technique used in the food business to separate and analyse ingredients,
vitamins, proteins, amino acids, and other nutritional components in food products. Chromatography can also be
used to identify the quantity of organic acids present and to identify any potentially harmful toxins that may have
been added to the food object in order to determine expiration dates.
, PHARMACEUTICAL AND DRUG TESTING: In the field of drug testing, chromatography is regularly employed as
a practical instrument. Every drug you take has been precisely identified by testing the components of the drug
before it enters your system.
FORENSIC SCIENCE AND TESTING: Analysing ink is another typical application for paper chromatography.
Forensic experts, for instance, can check bank checks for forgeries. Using this chromatography technique, lab
professionals can separate the pen ink from the paper to check whether it corresponds to the ink the suspect had
on them.
WHAT IS Rf VALUE AND HOW IS IT CALCULATED?
The retention factor is shown by the Rf value. It is the solvent's distance from the
baseline (solvent front) divided by the solvents’ distance to the spot (on
chromatography paper or plate). Since each solute in a given solvent has a unique Rf
value, the solute can be identified by knowing the Rf value in the solvent that was
employed. Rf values can be discovered in books or specialised databases. Because the
solute cannot go beyond the solvent, the Rf value is always smaller than 1. The Rf
value for a substance will change if the solvent is altered.
EXPERIMENT 1, TLC OF AMINO ACIDS:
EQUIPMENT:
● 150ml beaker (x2) ● Scalpel
● Sheet of photocopy paper (x2) ● Amino acids ( leucine, lysine, aspartic acid
● Sheet of aluminium foil (x2) and mixture of all three ) each to be
● TCL plate (x2) labelled as A,B,C and M
● Rubber bands (x3) ● Chromatography solvent ( attached )
● Pencil ● 5 capillary tubes ( one with each of the
● Ruler amino acids )
● Scissors ● Ninhydrin spray
● Hair dryer
RISK ASSESSMENT:
HAZARD RISK PREVENTIVE MEASURE ACTION TO BE TAKEN
Glassware Can break and can Do not keep any glass near edges and Get first aid, let other people know to
cause cuts handle them with care prevent further harm, use a pan and
brush to clean up and into the glass
bin.
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