The present invention provides a process for purifying a monoterpene or sesquiterpene having a purity greater than about 98.5% (w/w) The process comprises the steps of derivatizing the monoterpene (or sesquiterpene) to produce a monoterpene (or sesquiterpene) derivative separating the monoterpene (or sesquiterpene) derivative and releasing the monoterpene (or sesquiterpene) from the derivative Also encompassed by the scope of the present invention is a pharmaceutical composition comprising a monoterpene (or sesquiterpene) having a purity greater than about 98.5% (w/w) The purified monoterpene can be used to treat a disease such as cancer The present monoterpene (or sesquiterpene) may be administered alone or may be co administered with radiation or other therapeutic agents such as chemotherapeutic agents.
