EXTRACTION PROCEDURE:
1. Weigh out approximately 0.5 g of fresh spinach leaves (don’t use stems) and record the
mass. Tear the leaves into confetti-sized pieces and place them into a mortar. Add about
1.0 mL of acetone and grind the leaves with a pestle until the acetone turns a bright, deep
green. You may add more acetone as necessary.
2. Using a 5” Pasteur pipet, transfer the liquid to a centrifuge tube. Don’t be too concerned if
a small amount of sludgelike gunk is also transferred, it will be extracted later. Rinse your
mortar and pestle with another 1.0 mL of acetone and transfer this to the centrifuge tube also.
3. If you have more than 1.5 mL of acetone in the centrifuge tube at this point, it’s a good
idea to reduce the volume via evaporation in a warm sand bath. Don’t forget the boiling chip
or boiling stick or it will spatter. Allow the extract to cool to room temperature before the next
step.
4. Add 2.0 mL of hexane and 2.0 mL of distilled water to the extract in the centrifuge tube,
cork it and shake gently. Occasionally, DIRECT THE TUBE AWAY FROM YOURSELF AND
OTHERS, and vent. Soon, there should be a cloudy, light green lower water layer and a clear,
bright green top hexane layer. Be sure to identify which is the water and which is the hexane
Physiological Chemistry-Extraction of Chlorophyll from Spinach-4
layer. Allow the tube to stand a few minutes undisturbed to maximize separation of these
layers.
5. Using a 5” Pasteur pipet, carefully draw off the water layer and transfer it to a small waste
beaker. Remember to depress your pipet bulb before you insert the pipet into the centrifuge
tube.
6. Add another 2.0 mL of distilled water to the hexane layer in the centrifuge tube as a wash.
The new water layer should be very nearly colorless even after shaking and allowing the layers
to separate. Again, draw off the bottom water layer and combine it with the first one in the
waste beaker.
7. Although water and hexane ‘do not mix’…reality is that a little bit of the water will stay in
the hexane. You can tell there is water in the hexane layer; it may be a little cloudy. You
must ‘dry’ the hexane layer by adding some anhydrous Na2SO4. A few microspatula scoops is
usually sufficient. Na2SO4 soaks up the water as it becomes hydrated. However, you can be
sure you’ve added enough when additional Na2SO4 no longer clumps when swirled in the
extract and your extract is not at all cloudy. Ask your professor for help with this.
8. To remove the drying agent and filter your extract: prepare a filter pipet by inserting a small
cotton plug into a 5” Pasteur pipet. Using a micro clamp, secure the pipet on a ring stand and
place a clean collection vial below the stem of the pipet. Transfer your extract via
pipet to the filter pipet. The cotton plug will prevent any drying agent from contaminating
your extract as it drips into the vial. To complete the transfer, rinse the centrifuge tube
containing the drying agent with another 1.0 mL of hexane and filter this also.