Experiment #: 3
Title: Extraction – Isolation of Caffeine from Tea
Purpose:
The purpose of this experiment is to isolate and characterize caffeine from tea using both solid-
liquid and liquid-liquid extraction techniques. The process involves brewing tea to extract
caffeine into water, then using methylene chloride to separate it from the aqueous solution. This
experiment reinforces concepts such as solubility, phase separation, and purification, while
providing hands-on experience with extraction, drying, and melting point analysis.
Procedure:
1. Brewing the Tea (Solid-Liquid Extraction):
a. Shake tea to the bottom of two tea bags and tie them with the string.
b. Heat 15 mL of water in a beaker until boiling.
c. Add 2 g of sodium carbonate to the water and stir until dissolved.
d. Submerge one tea bag in the solution using a wooden stick and steep for
5 minutes, keeping the tea bag moist by adding water as needed.
e. Remove the tea bag carefully and squeeze out the liquid without breaking the bag.
f. Repeat the steeping process with the second tea bag in the same solution.
2. Liquid-Liquid Extraction with Methylene Chloride:
a. Cool the tea solution in an ice bath.
b. Transfer approximately 12 mL of tea solution into a centrifuge tube.
c. Add 2 mL of methylene chloride to the tube.
d. Cap the tube, gently mix by rocking, and periodically vent to release pressure.
e. Centrifuge the tube at ~50,000 RPM for 3 minutes to separate layers.
f. Use a pipette to remove the bottom methylene chloride layer and transfer to
a clean flask.
g. Repeat the extraction process two more times with fresh 2 mL portions
of methylene chloride, combining the organic layers.
3. Drying and Isolating Caffeine:
a. Add small portions of sodium sulfate to the combined methylene chloride
extract to remove water.
b. Swirl until clumping stops and free-flowing drying agent is visible.
c. Let sit for 5 minutes, then decant the dried solution into a clean, pre-washed flask.
d. Rinse the drying agent with a small volume of methylene chloride to
recover residual caffeine.
e. Heat the flask gently on a hot plate to evaporate the methylene chloride,
leaving behind solid caffeine.
4. Melting Point Analysis:
a. Scrape and grind the dried caffeine into a fine powder.
b. Load a small amount into a sealed melting point capillary tube.
c. Record the melting point range and compare to literature values.
Data/Results/Calculations:
• Mass of Caffeine Isolated: 28 mg
Title: Extraction – Isolation of Caffeine from Tea
Purpose:
The purpose of this experiment is to isolate and characterize caffeine from tea using both solid-
liquid and liquid-liquid extraction techniques. The process involves brewing tea to extract
caffeine into water, then using methylene chloride to separate it from the aqueous solution. This
experiment reinforces concepts such as solubility, phase separation, and purification, while
providing hands-on experience with extraction, drying, and melting point analysis.
Procedure:
1. Brewing the Tea (Solid-Liquid Extraction):
a. Shake tea to the bottom of two tea bags and tie them with the string.
b. Heat 15 mL of water in a beaker until boiling.
c. Add 2 g of sodium carbonate to the water and stir until dissolved.
d. Submerge one tea bag in the solution using a wooden stick and steep for
5 minutes, keeping the tea bag moist by adding water as needed.
e. Remove the tea bag carefully and squeeze out the liquid without breaking the bag.
f. Repeat the steeping process with the second tea bag in the same solution.
2. Liquid-Liquid Extraction with Methylene Chloride:
a. Cool the tea solution in an ice bath.
b. Transfer approximately 12 mL of tea solution into a centrifuge tube.
c. Add 2 mL of methylene chloride to the tube.
d. Cap the tube, gently mix by rocking, and periodically vent to release pressure.
e. Centrifuge the tube at ~50,000 RPM for 3 minutes to separate layers.
f. Use a pipette to remove the bottom methylene chloride layer and transfer to
a clean flask.
g. Repeat the extraction process two more times with fresh 2 mL portions
of methylene chloride, combining the organic layers.
3. Drying and Isolating Caffeine:
a. Add small portions of sodium sulfate to the combined methylene chloride
extract to remove water.
b. Swirl until clumping stops and free-flowing drying agent is visible.
c. Let sit for 5 minutes, then decant the dried solution into a clean, pre-washed flask.
d. Rinse the drying agent with a small volume of methylene chloride to
recover residual caffeine.
e. Heat the flask gently on a hot plate to evaporate the methylene chloride,
leaving behind solid caffeine.
4. Melting Point Analysis:
a. Scrape and grind the dried caffeine into a fine powder.
b. Load a small amount into a sealed melting point capillary tube.
c. Record the melting point range and compare to literature values.
Data/Results/Calculations:
• Mass of Caffeine Isolated: 28 mg
