PART
8. Repeat steps 5 through 7 using a second 5 ml portion of dichloromethane.
9. Add 0.5 g of anhydrous sodium sulfate to the combined dichloromethane extracts in the 25 ml Erlenmeyer flask. Swirl the contents of the flask. The anhydrous sodium sulfate will absorb the small amount of water that is dissolved in the dichloromethane and small amounts of water from the aqueous layer that may have gotten into the flask by accident.
10. Decant the liquid from the flask into a 25 ml beaker. Place one Boileezer into the beaker. Place the beaker on a hot plate and when the volume of material in the beaker is between 3 and 5 ml start adding petroleum ether by means of a Pasteur pipet. When the solution in the beaker begins to get cloudy remove the beaker from the heat and allow it to cool at your bench. With luck, crystals of caffeine will form in the solution.