Caraway seed oil contains mainly limonene and (+)-carvone. The (+)-carvone can easily be separated from the lower-boiling limonene by micro scale chromatography, a smaller amount of limonene and the isomeric terpenes, - and -phellandrene. Spearmint oil contains mainly (-)-carvone, with a smaller amount of limonene and the isomeric terpenes, - and -phellandrene.
A short disposable Pasteur pipet makes an appropriate column for microscale column chromatography. To prepare the column put a small piece of Tygon tubing over the tip of the pipet. Clamp the tubing with a screw clamp. With the help of a notched stopper, clamp the column, in a vertical position, to a ringstand. Place a small cotton plug at the bottom of the column and cover the cotton with a thin layer of sand (2 mm). add hexanes to the column and let about 1 mL of the solvent run.
This will get rid of air bubbles trapped in the cotton. Recycle the solvent for the next step. Obtain about 1 g of silica gel (silica gel 60 for column chromatography, 0.2-0.5 mm, 35-70 mesh). Mix the measured amount of silica gel with enough hexanes to make a pourable slurry.
Label five 20-ml scintillation vials 1-5. These vials will be used to collect the column fractions.
Follow the instructions given in section 9.2 to pack micrcolumns. After the column has been packed ,open the column outlet until the solvent level comes down to the top of the sand (not lower) and load the column with 150 microliters of the oil. Use a pluringe to measure the volume. Open the screw clamp and start collecting the eluent in the vial labeled "Fraction 1". Without allowing the column to run dry and after the sample...