Automated Solid and Resin Dispensing

Aapptech s ACTEVAP (Fig. 12) is a low-cost alternative for parallel evaporation that can be used either in combination with a rotary evaporator or as a stand-alone solution with a pump. The body is made from graphitized Teflon to provide the required heat conductivity. To ensure smooth evaporation without bumping, the cap of each of the up to 35 individual vessels is equipped with a frit to restrict gas flow. Vial volumes range from 4 to 40 mL. 

Before or during any synthesis involving solid supports, the appropriate amount of solid support must be dispensed into each reaction vessel. With increasing numbers of reaction vessels, this becomes quite labor-intensive and tedious. While it is possible to use a manual pipette or a pipetting robot and suspensions of resin in isopycnic solvent mixtures, other methods and devices for dry dispensing have come to the fore. 

Argonaut-Biotage offer the ArgoScoop Resin Dispenser , a pre-calibrated scoop with variable volume. In addition, simple resin-dispensing plate-based devices are available in various sizes from Mettler Toledo, Radleys (Titan), SciGene, and aapptech. These devices allow simultaneous addition of pre-determined amounts of resin to up to 96 reaction vessels of a reaction block (Fig. 13). 

Zinsser market automated resin dispensers that employ powder dispensing technology borrowed from the pharmaceutical industry. As a stand-alone device (REDI) or integrated in a standard pipetting robot (LIFOS, Eig. 13), a vacuum pipette with adjustable tips is used that is available in various sizes. Typical reproducibility is specified at 2 % for 50 mg and 1 % for 150 mg of support With one tip, resin can be dispensed, for example, into the 96 wells of a microtiter plate within about 15 min. 

Part of Chemspeed s Accelerator platform is the VLT 100 dual-dispensing station, which permits dosing of both liquids and solids, also under inert conditions if 

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