During chlorophyll extraction, a scientist must weaken the cell walls of a green leaf or plant, and then draw the chlorophyll out. Chlorophyll is housed inside each and every cell in green leaves, making it possible for plants to perform photosynthesis. As a liquid, chlorophyll will spill out of the leaves when treated with heat and placed in certain chemicals. This process generally destroys the leaves, so only a few leaves from any living plant should be used, in order to preserve the entire specimen.
Very green leaves typically respond better to chlorophyll extraction than pale green leaves. Spinach, kale, escarole, and any dark green leaves from trees generally work well. Pale lettuces and fuzzy lamb’s ear don’t usually work as well. The leaves should also be soft. Hard evergreen leaves, like holly leaves or pine needles, don’t usually break down enough to release their chlorophyll. Evergreens have developed many mechanisms for holding onto their resources and don’t generally give them up easily.
When performing chlorophyll extraction, the leaves must be heated and wilted. This may be done in one of two ways. The scientist may steam the leaves by placing them in a sieve over boiling water, or simply immerse them in the water. Steaming wilts and breaks down the leaves without turning them to mush. Some argue that this allows observers to see the extraction more clearly. Those using either cooking method should remove the leaves from heat when they’re very wilted, soft, and pliable.
The next step in chlorophyll extraction involves suspending the leaves in some kind of glass container. Empty baby food jars work well, as do clear glass drinking glasses. The container used for this experiment should not generally be used for food after the extraction is complete.
The scientist then usually bundles the stems of the wilted leaves together and gently knots them with cotton cord. When tied to the center of a pencil, the cord should allow the leaves to dangle in the glass container without touching bottom or the sides. Though this step isn’t necessary, it allows the scientist to remove the leaves from the container to show any color changes that take place after the chlorophyll has been removed.
Rubbing alcohol is the typical liquid of choice during chlorophyll extraction. It draws the chlorophyll out of the leaves and into the liquid. The scientist should simply fill the container to the brim with rubbing alcohol and let the assembly rest for about 20 minutes. The liquid should turn green. When the scientist lifts the leaves out of the liquid, they should be brown because there is no more chlorophyll in them.