Abstract
Afully automated, solid-to-solidweighingworkstation (patent pending) is described in this article. The core of this automated process is the use of an electrostatically charged pipette tip to attract solid particles on its outside surface. The particles were then dislodged into a 1.2-mL destination vial in a microbalance by spinning the pipette tip. Textures of solid that could be weighed included powder, crystalline, liquid, and semi-solid substances. Theworkstation can pick up submilligramquantities of sample (= 0.3mg) fromsource vials containing as little as 1mg. The destination vials containing the samples were stored in a 96-well rack to enable subsequent automated liquid handling. Using bovine serum albumin as test solid, the coefficient of variation of the protein concentration for 48 samples is less than 6%. The workstation was used successfully to weigh out 48 different synthetic compounds. Time required for automatedweighingwas similar tomanualweighing. The use of thisworkstation reduced 90% hands-on time and thus exposure to potentially toxic compounds. In addition, itminimized samplewaste and reduced artifacts due to the poor solubility of compound in solvents. Moreover, it enabled compounds synthesized in milligramquantities to beweighed out and tested in biological assays.