Bio-Rad Rotofor® and Mini Rotofor Cells - Manual (Page 29)

9.6 Uneven Harvesting
1. Use a stronger vacuum. Use vacuum that pulls >5 inches mercury.
2. Remove both harvesting and loading port covers. Before puncturing the
sealing tape to aspirate the fractions, remove both upper and lower covers. Do
not cover loading port holes with your fingers or gloves.
3. Run the Rotofor cell completely full. Volumes will vary in compartments as
the result of protein concentrations in each.
4. Check the needles in the harvesting block, the tubing and the harvest
block lid. They should not be loose, kinked, plugged, or unequal in height.
5. Check the plastic harvest tubing. If necessary, soak the tubes in dilute
NaOH (0.1 M) to remove residual matter then rinse the tubes with water.
Caution: DO NOT insert all of the needles into a water bath at the same time
with the vacuum on, as the harvest box may implode! Dry the tubes one at a time.
9.7 Mechanical Problems
1. The cell doesn’t rotate. Make sure that the core is assembled tightly, and that the
gear teeth are meshing well. With each hand, grab the big black rings that hold the
halves of the electrolyte chambers together and tighten them simultaneously for
better leverage. (Also make sure that the switch is set to “run” and not “harvest”).
Refer to the manual for proper assembly.
2. The unit leaks. Leaks from different places indicate different problems:
A) Vent buttons may become wet under normal operation, but this is usually
attributable to condensation during the run, not to leaking. If they are old
(>4–5 runs), or the electrolyte chamber is more than 2/3 full, they may
actually leak. Replace the vent buttons if they are old. Make sure electrolyte
solutions are 0.1 Molar.
B) Check the ion exchange gaskets between the two halves of the electrolyte
chamber to make sure that there is a good seal between them. They
should not be wrinkled, pinched, or out of alignment.
C) Check the O-rings that seal the chamber from the cooling finger. If one or
more of them is twisted, cracked, or missing, the unit may leak. To keep
the O-rings from twisting as you put the unit together, lubricate them with a
small amount of silicone grease, or Cello-Seal.
D) The cell must be seated firmly in the electrodes with the screws tightened.
3. The focusing chamber is too long for the base. Push the assembled
components all completely together on the cooling finger. To properly seat the
pieces together may require some force.
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