Standardized Extract
Short story: Dissolve a measured quantity of Salvinorin A in a solvent, and then absorb it onto a measured quantity of crumbled salvia leaves. Evaporate off the solvent, and it is done.

Thorough explanation: To make salvinorin A enhanced leaf that contains 15 mg salvinorin A per gram of leaf, dissolve 12.5 mg pure salvinorin A in 1 ml of warm acetone, and then add 1 gram of crumbled salvia leaves and stir. The leaves will absorb the salvinorin A-containing acetone. Place the container in a well-ventilated location and wait for the acetone to evaporate off. Stir the leaves occasionally during the evaporation period. Make sure that the acetone has evaporated completely--there should be absolutely no smell of acetone left on the leaves. This presumes that an average of 2.5 mg of salvinorin A per gram is already present in the leaf.

The amount of salvinorin A to use will vary depending on the salvinorin A content of the leaves that it is being absorbed onto. If the leaves are of average potency, containing 2.5 mg salvinorin A per gram, then you would deposit 12.5 mg salvinorin A onto them to bring the concentration to 15 mg per gram (as in the above example). Of course, one can standardize the leaves to other concentrations as well. The more precisely you know the salvinorin A content of the leaves, the more accurately you can standardize them. I use very pure salvinorin A for this procedure. If you are using salvinorin A that is not perfectly crystallized due to remaining impurities, you will need to take into consideration the percentage of impurities when calculating the amount of material to use. The same technique can be used to deposit salvinorin A onto other types of leaf.

For instance if deposited back onto salvia leaf that has had the salvinorin A removed, standardization becomes somewhat simpler. For each gram of leaf, deposit 15 mg of salvinorin A, and the leaf is standardized to 15 mg per gram, with no guess work as to what the leaf contained in the first place. The same holds true for garden sage (S. officinalis) which has no salvinorin A by default.

Smoking leaf that contains more than 15 mg salvinorin A per gram is strongly discouraged unless the individual doses can be accurately weighed. At this concentration, the amount of smoke produced provides a certain amount of safety because it makes it difficult for a person to accidentally inhale too large a dose in a single inhalation.