Figure 2.

Characterization of osmotic pump rate in vitro. (A) Diagram of how osmotic pump activity was tested in vitro using trypan blue dye. Osmotic pumps were filled with trypan blue dye and placed in 50-ml conical tubes containing saline solution. Activity was determined by measuring the optical density (OD590) of trypan blue in saline over 4 weeks. (B) The levels of trypan blue effluxed into saline solution were plotted against OD590. (C) Volume of trypan blue pumped out was plotted over time.