Bio-Rad ChromLab™ Software - Manual (Page 255)

UV or UV/Vis Detector
Instrument Guide | 253
UV or UV/Vis Detector
Symptom Possible Cause Possible Solution
The UV baseline is
unstable or noisy.
The UV baseline shows
a reproducible zig-zag
or sawtooth trace.
Air bubbles are trapped in the flow
cell.
Note: Always degas buffers
and solutions before use.
 Degas buffers by stirring
vigorously under vacuum for
approximately 20 min.
Important: Use a
heavy-wall, side-arm
Erlenmeyer flask, as
standard flasks may
implode under vacuum.
 Plumb the detector with the
column outlet connected to
the bottom of the flow cell.
This forces air bubbles to rise
to the top of the flow cell and
dissipate.
 Use the 40 psi backpressure
regulator supplied with the
NGC system to remove most
air bubbles. Place it directly
after the conductivity flow cell
and run buffer for several
minutes.
If the chosen column cannot be
run with the backpressure
regulator, and air bubbles are a
continuing problem (for example,
during some affinity
chromatography steps), use the
2 mm path length flow cell. The
straight line flow of the flow cell
makes it easier to remove
bubbles.