PowderPicking: An inexpensive, manual, medium-throughput method for powder dispensing

Many applications in late discovery/early stage formulation require repetitive accurate dispensing of solid powders. This is often performed manually using spatula and micro balance since existing automated dispensing systems are too expensive or the required starting mass is not available. In this study, commercially available Gilson MICROMAN® positive displacement pipettes with disposable capillary piston tips were used for manual, volumetric dispensing of solid powders. Tips were filled with powder by pushing them several times into the powder (PowderPicking) and powder was expelled with the push button into target vessels. Results obtained with 10 solid drug and excipient powders with largely different size and shape indicate that the technique can be employed for repetitive powder dispensing in the 0.6 mg to 25 mg range with acceptable accuracy (average %CV in delivered mass for all dispenses was 6%). The technique is easy to calibrate and perform, rapid, inexpensive, and compound-saving, adapted to the daily demands in laboratories, and can help to close the gap for powder dispensing between labor-intense, manual weighing and expensive, high-end automated systems.