The "equipment" is formulated from devices currently being marketed under the category of "solid phase extraction" (SPE). These are available from several sources and come in various sizes. We have used primarily 8.0mL sized items from Alltech Associates, Inc. Similar items are available from Millipore, Burdick and Jackson, Supelco, J.T. Baker, and most chromatographic supply houses. SPE "tubes" or "reservoirs" are essentially polypropylene syringe barrels. Frits made of 20 micron porous polyethylene are available to fit into the tubes. A frit is pressed into the bottom of a tube and the desired amount of supported material added. A second frit can be placed on top to hold the support, but this is not always necessary or desireable. In general, the frits and tubes can be reused several times.
Other useful items are adapters to stack two or more tubes in series, and caps for the ends of the tubes. With some supports, particularly ion exchange resins, reactants in solution can flow through by gravity, but in other cases, usually when silica, alumina, or clays are used, it is necessary to be able to apply a vacuum. Commercial vacuum manifolds are available and convenient, but expensive. A filter flask or side arm test tube fitted with a syringe needle through a stopper will serve the purpose.
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