32
Simple Maintenance
Adjusting the Path Length of Preparative Flow Cells
SOP 14
Changing the Path Length of Preparative Flow Cells
(A4133, A4134, A4135 - only)
Path lengths can be adjusted to 2, 1.25 and 0.5 mm. On delivery, the
path length is set to 2 mm. To reduce the path length to 1.25 or 0.5 mm,
follow the instructions given:
1. Unscrew the fiber optical connector with a wrench.
2. Take out the PEEK shutter and the PEEK distance plate.
3. Remove the distance plate, put back the shutter and refasten the
connector carefully.
With the distance plate removed, the rod shaped light guide is pushed
further into the flow cell (0.75 mm), thus resulting in a reduced path
length of 1.25 mm. To reduce the path length further to 0.5 mm, follow
the same procedure on the other side of the cell.
To extend the path length again in steps of 0.75 mm, the PEEK distance
plates have to be inserted again:
1. Loosen the fiber optical connector, remove the shutter and take out
the gasket holder by using a pair of tweezers.
2. Push the light guide approximately 1 mm to the outside to enlarge the
path length. Use a clean cloth and do not touch the light guide with
the fingers.
3. Put the gasket holder back into the cell.
4. Insert the PEEK distance plate again and then the shutter.
5. Fasten the fiber optical connector carefully.
When fastening the connectors, the rod-shaped light guide is pushed
back in the correct position inside the cell. Inserting a distance plate thus
enlarges the path length to 0.75 mm. It is not necessary to change the
PTFE sealing ring when adjusting the path length.
Problems and possible Causes
Problem
Possible causes
Solution
High integration time Cell is dirty
Please clean the flow cell.
Eluent absorption to
high
Please replace the eluent.
Please try to work at a
different wavelength (less
absorption by the eluent).
High integration time,
even with a clean
flow cell
Old lamp
Please replace the
deuterium lamp.
Spikes in the
baseline
Bubbles
Please check the tubes on
the intake side of the
pump for leakage.
Please use a degasser.
Please try to purge the cell
at high flow rate.
Please check with dry cell.
High drift
Cell is leaking
Please eliminate the
leakage.
large temperature
changes
Please work at constant
room temperature..
Table 6
Other problems
