PLANT GRINDING AND EXTRACTION
Plant specimens, air dried in the field and averaging 700 GMS, are first finely ground into a powder resembling sawdust using a variety of mills including bandsaw, hammermill or knife mill. The powder is added to a 10cm diameter borosilicate column and covered with dichloromethane/methanol (1:1) and allowed to steep overnight at room temperature inside a chemical fume hood. The solvent is drained, and the column filled with 100% methanol. After 30 minutes the methanol is drained into the same flask and the combined organic solvent is concentrated by rotary evaporation, then transferred into a 120ml borosilicate bottle for final high vacuum drying and permanent storage. To the extracted plant material in the column high purity water is added, and this is allowed to steep overnight. We have determined that this solution contains typically 5 to 8% methanol, which improves extractability of molecules into the water. The aqueous extract is transferred into a borosilicate dish, frozen and lyophilized. The dry powder is transferred into a 120 ml borosilicate bottle for long term freezer storage. Though highly variable, we have observed that it is not unusual for 10% of the weight of a specimen is organic solvent soluble and an additional 10% is water soluble.
This graph shows the number of Plant organisms extracted per year between 1987-2011. 3118 plants were extracted in 2011.
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