Bio-Rad BioLogic QuadTec™ Detector and Components - Manual (Page 51)

Problem Possible Cause Suggested Solutions
Negative peaks. The sample is applied to
the column in a different
buffer from that used to
equilibrate and elute the
column. Refractive index
changes may be
responsible for the
negative peaks.
The elution buffer may
have a higher UV
absorbance than the
sample components.
False or ghost The injection valve,
peaks. injection port, and loop
were not rinsed out
between sample
injections.
Strongly-retained sample
components may still be
eluting from a previous
run.
TROUBLESHOOTING SYSTEM INSTALLATION AND SETUP
6-4
1. Apply the sample in the same buffer used to
equilibrate the column.
2. Check the elution buffer’s UV absorbance.
1. Rinse valve, port, and loop with buffer. For
example, if the sample loop contains 100 µl, then
program a load/inject volume of 200 µl to
completely flush the valve and loop.
2. Always clean large volume dynamic loops, such as
the Bio-Rad DynaLoop™, between use to avoid
cross contamination.
3. Use stringent elution conditions or consult the
column’s user manual for an appropriate wash
step to remove such components between runs.