This is an in depth assessment discussing the different types of chromatography techniques, applying chromatography and interpreting a chromatogram. Including paper chromatography and TLC (thin layer chromatography).
BTEC Level 3 Applied/Forensic Science
Unit 2: Practical Scientific Procedures and Techniques
Learning Aim C: Undertake chromatographic techniques to identify
components in mixtures
Introduction:
Chromatography is the process for separating components of a mixture (ThermoFisher,
2019). Chromatography has many uses in medicine and industry, for example to create
vaccines, food testing, drug testing and forensic testing. The process of chromatography
separates the molecules because they all have different solubilities in the solvent. We will
be carrying out three experiments, the first two using paper chromatography and the other
using thin layer chromatography (TLC). The first experiment we will be carrying out is the
paper chromatography of extracted plant pigments, we will be using spinach. For the
second experiment we will be using paper chromatography to identify the amino acids
present in a mixture. For the final experiment we will be carrying out the TLC of extracted
plant pigments.
Paper chromatography:
In paper chromatography, the pigments will travel at different rates and distances as they
are not equally soluble, the most soluble will travel the furthest distance and a less soluble
pigment will travel the shortest. Paper chromatography uses a thin absorbent paper.
TLC (Thin Layer Chromatography):
Thin layer chromatography (TLC) is a thin, uniform layer of silica gel coated onto a piece of
glass, metal, or rigid plastic (Jim Clark, 2019). TLC uses the same techniques for paper
chromatography but instead of paper it is TLC.
, Part 1: Paper chromatography of plant pigments:
Equipment:
- Chromatography paper
- Beaker
- Measuring cylinder
- Running solvent
- Pencil
- Ruler
- Spinach
- Pestle and mortar
- Propanone
- Scissors
- Hairdryer
- Lid
- Capillary tube
- Pipette
- Container/tank for chromatography paper
Risk assessment:
Hazard Risk Control measures
Propanone - Irritant - Wear eye
- Flammable protection, goggles,
- Can cause eye and gloves
damage and - Use a fume
irritation cupboard
- Can cause skin - Keep away from
dryness naked flames
- Keep away from
mouth and eyes
- Avoid breathing in
fumes
Broken glassware - Can cause cuts and - Clean any broken
scratches glass immediately
- Can be dangerous - Keep glass on centre
of table
Running solvent - Can cause irritation - Wear goggles and
on the skin gloves
- Wash any off if you
get it on the skin
Spilt liquids - Can cause trips and - Clean/dry up
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