Bio-Rad PROTEAN® IEF Cell Accessories - Manual (Page 9)

Figure 6. Twelve-cup strip.
Note: When cutting the indent of the bridge between two cups, ensure that no burrs remain in
the cut that would prevent the bridge from sitting directly on the wall that divides two channels
in the focusing tray.
2. Place the sample cups on the gel surface near the anode for basic pH range IPG strips and
near the cathode for acidic pH range IPG strips. To position the sample cups properly, make
sure that the bridges connecting two cups are pushed down onto each wall that divides the
focusing tray channels.
Figure 7. Side view of Focusing tray with IPG strips, cups, and sample.
Note: Improper placement of the sample cup can result in sample leaking.
3. When the cups are securely positioned, add the protein sample to the sample cups. We
recommend a maximum of 100 µl for the smaller cups and a maximum of 150 µl for the large
volume cups. We have observed improved resolution with smaller volumes containing a higher
protein concentration, and recommend using the maximum protein concentration possible in
which proteins do not precipitate.
Tray
Tray well
IPG strip and gel
Cup
Pipet tip
Sample
Locking
tabs
Cut
7
Connecting bridge