Methods for making trans-(-)-” 9 -tetrahydrocannabinol and trans-(+)-” 9 -tetrahydrocannabinol are disclosed herein. In one embodiment, a trans-(-)-” 9 -tetrahydrocannabinol composition is prepared by allowing a composition comprising (±)-” 9 -tetrahydrocannabinol to separate on a chiral stationary phase to provide a trans-(-)-” 9 -tetrahydrocannabinol composition comprising at least about 99% by weight of trans-(-)-” 9 -tetrahydrocannabinol based on the total amount of trans-(-)-” 9 -tetrahydrocannabinol and trans-(+)-” 9 -tetrahydrocannabinol. The invention also relates to methods for treating or preventing a condition such as pain comprising administering to a patient in need thereof an effective amount of a trans-(-)-” 9 -tetrahydrocannabinol having a purity of at least about 98% based on the total weight of cannabinoids.
