This keeps happening to my bis-tris gel during running. Bubbles form in the gel near the cathode wire, and the proteins/dye front stops running at the bubbles. This never happened with the tris-glycine gels that I used to use, but our lab has recently purchased an mPAGE Lux casting system.

The gel was made using the mPAGE Lux casting system, and the buffer is a homemade MOPS buffer (20 mM MOPS, 5 mM sodium acetate, 1 mM EDTA, pH adjusted to 7). It's run at 130 V. My first thought was overheating near the cathode, but pre-chilling the buffer, adding an ice pack in the tank, and running in the cold room still did not prevent it.

Has anyone experienced this, and how were you able to fix this issue? Thank you!