Edexcel A Level (IAL) Biology -1.14 Core Practical 2: Investigate the Vitamin C Content of Food & Drink- Study Notes- New Syllabus
Edexcel A Level (IAL) Biology -1.14 Core Practical 2: Investigate the Vitamin C Content of Food & Drink- Study Notes- New syllabus
Edexcel A Level (IAL) Biology -1.14 Core Practical 2: Investigate the Vitamin C Content of Food & Drink- Study Notes -Edexcel A level Biology – per latest Syllabus.
Key Concepts:
- 1.14 vestigate the vitamin C content of food and drink.
CORE PRACTICAL 2 – Investigating Vitamin C Content in Food and Drink
🌱 Aim
To determine and compare the vitamin C content of different foods and drinks.
⚡ Key Concept
Vitamin C is a water-soluble antioxidant that can be titrated with DCPIP (2,6-dichlorophenol-indophenol), a blue dye which is reduced and becomes colourless when it reacts with vitamin C.
🧬 Principle
- Vitamin C reduces DCPIP from blue → colourless.
- The amount of DCPIP used tells us how much vitamin C is present.
- Can be done by titration (quantitative) or visual comparison (semi-quantitative).
📝 Materials
- DCPIP solution (0.001 M)
- Food/drink samples (orange juice, lemon juice, kiwifruit, soft drinks, etc.)
- Distilled water
- Burette / pipette / conical flask
- Measuring cylinders, test tubes
- Protective gloves and goggles
🔹 Method (Titration)
- Prepare Samples: Extract juice from fruits or dilute drinks if needed. Filter to remove pulp.
- Set Up DCPIP: Fill a burette with DCPIP solution.
- Titration: Place a known volume of juice (e.g., 10 cm³) into a conical flask. Add DCPIP drop by drop while swirling until blue → colourless. Record volume used.
- Repeat: Do at least 3 repeats for accuracy.
- Calculate Vitamin C Content: Using known DCPIP concentration, calculate vitamin C in the sample.
🔹 Method (Semi-Quantitative/Visual)
- Prepare vitamin C standards with known concentrations.
- Add DCPIP dropwise to each standard until colour disappears.
- Compare drops needed for sample → estimate vitamin C content.
⚠️ Precautions
- DCPIP is light-sensitive → keep in dark bottles.
- Vitamin C destroyed by heat and light → handle samples quickly.
- Rinse glassware thoroughly to avoid contamination.
- Swirl constantly to prevent localised overreaction.
📊 Observations
| Sample | Volume of DCPIP used (cm³) | Vitamin C concentration (mg/100 cm³) |
|---|---|---|
| Orange juice | 8 | 50 |
| Lemon juice | 10 | 40 |
| Soft drink | 3 | 15 |
Values above are examples, actual values depend on the sample.
⚡ Results Interpretation
- More DCPIP needed → higher vitamin C content.
- Fresh juices usually have more vitamin C than soft drinks or processed juices.
- Helps compare nutritional value of foods/drinks.
🧠 Quick Recap
DCPIP test: Blue → colourless = vitamin C present.
More drops of DCPIP = more vitamin C.
Precautions: protect from light & heat, rinse glassware, swirl constantly.
Purpose: assess vitamin C levels for dietary evaluation.