64 Agilent 7890 Series Troubleshooting
3 Chromatographic Symptoms
and application. It may be different for different situations but
as a general rule, the following values apply (Table 4). Figure 3
shows typical uECD life cycle stages.
Tab le 4 uECD signal evaluation
ECD signal Comments
<200 uECD is “healthy”.
200 to 400 Slightly elevated, no cause for
concern at this point. Signal still in
“good” range.
400 to 1000 System showing signs of
contamination from gases, column, or
samples. If the signal increases in
response to increased oven
temperature, suspect the column.
1000 to 2000 Suspect more severe contamination,
follow the troubleshooting guidelines.
>2000 If the following procedures do not
work, suspect the uECD cell.
It may take 24 hours for the uECD baseline to completely stabilize,
especially if you are starting with a cold system and want to assure
high-sensitivity operation. For the most accurate results, run the detector
at normal operating conditions for as long as possible (at least 2 hours
and up to 24 hours) before running the frequency test.
If you will be injecting into an unused inlet, you must use low-bleed septa.
Make sure to condition new septa before use in an inlet for several hours
with 1 to 5 mL/min carrier flow.
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