Bio-Rad BioLogic LP System User Manual
Page 97
6.6 TROUBLESHOOTING
Listed below are some guidelines for troubleshooting the system:
Unstable baseline. This may be caused by any of the following:
•
Bubbles in Flow Cell: BioLogic LP Flow Cells are designed to clear bubbles. Confirm that the flow
cell tubes are connected properly. Note the flow direction arrows on top of the UV Optics module
case. Be sure that the UV Optics module is mounted upright on the rack, with the mounting posts
pointing down.
•
Dirty or Obstructed flow cell: Turn the UV lamp “off” , remove the flow cell, and look through the
sample window. If visible obstruction is seen, clean the flow cell (see section 6.3).
•
Light leaks: The optics module case is sealed against light by three O-rings- One each on the flow
cell and filter drawer, and one between the case halves. To check for light leaks, pump buffer
through the unit, and squeeze the optics module case halves together gently, using your thumb and
forefinger. Observe the chart recorder pen- if squeezing the optics module causes noticeable deflec-
tion of the UV (channel 1) pen, a light leak is probable.
If a light leak is suspected, turn the UV lamp off, remove the flow cell and filter drawer, and confirm
that the O-rings are in place. Remove the four screws holding the case halves together, separate
the case halves, and confirm that the sealing O-ring is in place. Reassemble the optics module and
repeat the test for light leaks.
•
Lamp exhausted: If the UV lamp is nearing the end of its service life, the base line may become
unstable. Replace lamp.
Flow rate is not as displayed.
•
Check for worn tubing, and confirm that platen pressure is adjusted properly. Refer to section 4.2.
•
Check pump calibration:
a.
If Nominal calibration is used, confirm that proper tubing size is selected. Consider performing
User calibration. Refer to section 6.2, Pump Plumbing and Calibration.
b.
If User calibration is used, repeat calibration- it is best to calibrate with column, etc. installed in
system, and with the actual buffers used for the separation. Set the flow rate to the same rate
used for the separation. Refer to section 6.2, Pump Plumbing and Calibration.
•
Check for obstructed tubing , columns, or valves.
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Maintenance and Troubleshooting