Unit 2- Practical Scientific Procedures and Techniques
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BTEC Level 3 Applied Science Unit 2C
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Unit 2- Practical Scientific Procedures and Techniques
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PEARSON (PEARSON)
Hello, this is a D* (Distinction) grade on unit 2C . All criteria have been accomplished in this assignment. Various methods of chromatography have been explained. By reading this assignment you will understand what the assessor and examiner want to hear from you and what they are looking out for s...
Unit 2- Practical Scientific Procedures and Techniques
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I am a new technical assistant at a large chemical plant named Chemcalequip.
I am separating chlorophyll pigments with paper chromatography and amino acids with TLC.
Different types of chromatography:
Gas chromatography: Is the use of gas as the mobile phase; it has the ability to separate hundreds of compounds and measure organic
molecules and gases. A few uses of gas chromatography are: Pharmacies use gas chromatography to identify how much of a drug is in the
medicine to make sure it has the correct dosage and affectability, gas chromatography can also be used to monitor pollution levels in the air to
determine whether the air is clean or heavily polluted and gas chromatography can also be used to test for drugs in bodily fluids e.g., to check if
athletes are not using any performance enhancing supplements to aid them to the position they are at.
Ion exchange chromatography: Relies on the attraction between oppositely charged substances between the mobile and stationary phase. It is
used to separate ions and polar molecules based on their affinity to the ion exchanger; It works on almost any charged molecule. It is used for
water analysis to test for any contaminations and minerals, for the purification for proteins and other organic substances.
High performance liquid chromatography: HLPC can use it to analyse proteins, water quality, additives and contaminants in food.
Method:
1. The mobile phase is connected to a delivery pump which speeds up the whole process.
2. The liquid sample gets added through a different entrance.
3. It is then carried by the mobile phase through the column (stationary phase).
4. Next, the interaction happens and sample is separated.
5. After, a detector converts the amount of each component into an electrical signal.
, Paper chromatography- This is used to separate impure substances and identify the different compounds within the substance or to see if it is a
pure substance including only one element.
This is the step-by-step process of paper chromatography (testing for chlorophyll):
Make sure safety is priority #1:
• Wear gloves because skin can absorb harmful chemicals
• Wear safety goggles and move chairs or tripping hazards out of pathways
•Tie long hair back, roll up sleeves
• Make sure to take off unnecessary accessories such as jewellery or lanyards etc.
Additional information/ common mistakes:
• Make sure experiment in at room temperature for results not to be altered
• Do not use ink (e.g., for the origin) unless being tested
• Place chromatography paper vertically straight in beaker
• Mark solvent front and distance travelled by substance to later calculate Rf value
Method:
1: Gather your equipment: Pestle & motar, few leaves of spinach, distilled water, solvent mixture (90% petroleum ether,10% acetone), splint,
paperclip, capillary tube, tube stand, test tube, measuring tube, sand and 2 chromatography papers.
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