Caffeine Extraction Lab.docx

Caffeine Extraction Lab BE 3340 Dr. Sabliov Jonathan Thomas 26 March 2019

Introduction Caffeine is an alkaloid (shown in Figure 1) that is used recreationally to stimulate the central nervous system to provide energy in beverages such as coffee, tea, and soda, and in pharmaceuticals, to treat headaches and drowsiness. Primary sources of caffeine are leaves, nuts, and seeds found from plants in South America and East Asia. Solvent extraction is primarily used to extract the caffeine from the plants in the manufacturing industry.

Figure 1. Chemical structure of caffeine

Objective The objective of this lab was to extract 85% of 111 mg/packet of caffeine from coffee inside of a 8 oz. Folger’s Classic Roast within an 1 hour and 30 minutes.

Materials Materials for this lab included: safety goggles, Folger’s Classic Roast coffee bag, 50 mL and 100 mL glass beakers, distilled water, aluminum foil, 15 mL centrifuge tubes, beaker tongs, Pasteur pipet, hot plate, analytical balance, centrifuge, Dichloromethane (DCM), 1 M Na2CO3, Na2SO4 crystals, ice bath, and a hot water bath.

Methods First, all personal protective equipment was put on. The mass of the coffee bag was recorded and the mass of the empty coffee bag was provided. 20 mL of the 1 M Na2CO3 solution was poured into a 100 mL beaker. The coffee bag was added and covered with foil and heated on the hot plate till reached boiling point. As the solution was allowed to boil for five minutes, distilled water was added as needed to maintain 10 mL of solution. After having been boiled for 5 minutes, the beaker containing the solution was removed from the hot plate and allowed to cool, and the coffee bag was squeezed to get as much liquid out

as possible. Once cooled, the coffee bag was removed and discarded, ideally leaving behind 8 mL. The cooled extract was then transferred to a centrifuge tube where 3 mL of DCM was added, and the tube was screwed closed. The tube was then shaken for 30 seconds, relieving the pressure after shaking by unscrewing the cap partially every 10 seconds. The mixture in the centrifuge tube was then centrifuged for 4 minutes. After retrieving the mixture from the centrifuge, the clear bottom layer of liquid was removed from the tube using a Pasteur pipette and transferred to an empty vial. The dark upper layer was left in the tube. The centrifuging/pipetting process was then repeated two more times, each time transferring the clear liquid into the appropriate collection tube. After the last extraction was completed, the dark liquid was discarded appropriately in a designated waster container under the fume hood. Then, a pea-sized amount of Na2SO4 crystals was added to the collection tube containing the clear liquid. This mixture was then sealed by the cap and swirled gently. This was repeated until no more clumping of crystals occurred. Finally, the clear liquid in the collection tube was decanted into a 50 mL beaker, this was then placed into a hot water bath at 45 oC under the fume hood to evaporate the DCM and leave only the caffeine. Once all the solvent was evaporated, the beaker was removed leaving only the crude caffeine in the beaker. These steps can be viewed in Figure 2.

Figure 2. Detailed flowchart for caffeine extraction

Figure 3. Equilibrium Stage diagram of caffiene extraction

Discussion The expected extraction of caffeine for one 8 oz. coffee bag is theoretically 111 mg of caffeine per cup, if 100% extraction is achieved. Mass of the beaker with caffeine was 29.1545 g, the mass of the clean, dry beaker was 29.1228 g and the caffeine extracted was calculated to be 31.7 mg/cup, with an expected percentage of 85%. Error could have been achieved as not enough Na2SO4 crystals could have been added. Na2CO3 was used in this experiment as it used to help

extract all the other insolubles that is not caffeine, and the DCM was used for the caffeine extraction.