The PROTEAN® i12™ IEF system is used for isoelectric focusing (IEF) on immobilized pH gradient (IPG) strips for the first dimension of two-dimensional (2-D) electrophoretic protein analysis. The PROTEAN i12 IEF cell can run 1 to 12 IPG strips in 7, 11, 13, 17, 18, and 24 cm focusing trays. Each channel in the i12 focusing tray is powered by its own power supply, enabling precise control over each IPG strip. This makes it possible to run different sample types, different pH gradients, and multiple protocols all at the same time.       
       
The i12 focusing trays and electrode assemblies accommodate all possible gel configurations (gel-side up or down, with or without electrode wicks). The trays also allow sample loading either by inclusion in the rehydration solution (in-gel loading) or with sample cups (sample cup loading).       
       
It is easy to set up runs and to create and edit protocols from the user interface; connection to an external computer is not required. Each protocol can contain up to ten steps in which the voltage, manner of voltage ramping, current, and duration (hr or Vhr) are defined.       
       
Preprogrammed protocols stored in the internal memory serve as a convenient starting point for developing optimized sample-specific IEF conditions. A USB flash drive can also be used as an alternative storage location or method of transfer for protocols and run data files.