Menthol by Polarized Light Microscopy


Menthol is an organic compound with the formula C10H20O. Is is commonly produced from corn mint, peppermint or other mint oils and is a waxy crystalline substance which has local anesthetic and counter-irritant properties. Interestingly it's ability to trigger cold-sensitive TRPM8 receptors on the skin is responsible for the cooling sensation when inhaled, eaten or applied to the skin.

It is used in many products as an anti-puretic, as a topical analgesic, to treat sunburns, as a pesticide, and even in perfume.


How it was done:

Since the melting point of Menthol is very low (~ 31 Degrees C) this is easily prepared by the Melt method. To prepare the sample a small amount of menthol crystals was placed on a concave microscope slide, and slowly passed across a Bunsen burner flame being careful not to boil the menthol of the slide or catch it on fire. Once the menthol had melted into liquid it was removed from the flame and left to recrystallize.

The image was then captured using my normal polarized microscopy setup, which included;

Because the depth of field is relatively small, some images did require focus stacking which is where Helicon Remote & Focus came into the picture (pardon the pun).


Images: (Click to enlarge)

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