Caffeine Extraction Lab Report

Introduction

The purpose of this experiment was to practice the extraction technique to isolate a substance: caffeine was extracted from tea leaves. This was a technical experiment that used a solvent in combination with a separatory funnel apparatus and vacuum filtration to remove and isolate everything except pure caffeine from the solid mixture (tea).

Physical Data Table

Procedure

1. Dump and weigh the contents of teabags.
2. Place tea bags into a clean 150mL beaker.
3. Add 30 mL of DI water and 2.0g of anhydrous sodium carbonate.
4. Heat until it boils.
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5. Pour off the liquid into a 50 mL beaker.
6. Repeat steps 3-5 with an additional 20 mL of DI water.
7. Note: press tea bags gently without breaking to extract the greatest amount of liquid possible.
8. Transfer tea to a 125mL separatory funnel.
9. Add 10mL of Dichloromethane to the funnel.
10. Allow contents to settle; there should be two distinct layers.
    • If there is a cloudy layer, try to break it up by swirling contents or using a glass rod.
11. Drain the lower clear-yellowish (Dichloromethane) layer into a 25mL flask.
12. Repeat steps 9-11 with an additional 10mL Dichloromethane.
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13. Add 0.5 g of anhydrous sodium sulfate to the Dichloromethane extract in the 25mL flask.
14. Swirl contents.
15. Pour the liquid from the flask into a 25mL beaker.
16. Place it on a hot plate; when the volume in the beaker is about 10mL or lower, add petroleum ether by a Pasteur pipet.
17. When the solution gets cloudy, remove it and allow it to cool; crystals of caffeine will form.
18. Set up vacuum filtration; pour in crystals and solution and allow to dry.
19. Weigh the crystals.

Data Table and Observations

This experiment was a solid/liquid extraction. The procedure was carried out as planned. During separation of the mixture, the emulsion was broken by the use of a glass rod. A significant amount of caffeine was recovered during this extraction: in total, the percent recovery was 0.521%.

Discussion of Results

The amount of caffeine extracted was 0.521% recovery (0.0252g) from the original mass of 4.84g of tea leaves. Our solute was identified as pure caffeine by the extraction procedure, including the separation funnel and Vacuum filtration technique, that left pure caffeine crystals.

The total amount of caffeine extracted was 0.0252g. Typically, the amount of caffeine in one tea bag is (30-50mg). Using 0.05 g, we had extracted about 25% of our theoretical yield (( frac{0.0252}{0.1 text{g}} times 100 )), which shows the accuracy of our experiment.

Since the highest amount of total caffeine that could have possibly been extracted from the two tea bags was about 110 mg, this demonstrates that there may have been loss of product throughout the procedure. One loss of product could have occurred during separation due to the emulsion layer that we were careful to not include when decanting the aqueous layer.