Agilent 1100 Series Fraction Collectors User’s Guide
29
Configuration and Operation of the Fraction Collector
1
Setting up a Fraction Collector Method
Working Mode
For each peak detector
Threshold only
,
Threshold/Slope
and
Slope
only
are possible. In the Threshold only mode the settings for Up Slope, Down
Slope and Upper Threshold in the subsequent columns are ignored. Fraction
collection is triggered whenever the detector signal exceeds the specified
threshold value. When the signal drops below the threshold value fraction
collection is stopped. In the Slope only mode fraction collection is triggered on
the slopes of the detector signals. Adequate values for Up Slope and Down
Slope can be specified in the corresponding fields. In the Threshold/Slope
mode fraction collection is triggered on the corresponding values for threshold
and slope. The fraction collection is started if the detector signal exceeds both
the threshold and the Up Slope value. The fraction collection is stopped if the
detector signal drops either below the threshold or the Down Slope value.
To specify the trigger values
Up Slope
,
Down Slope
,
Threshold
and
Upper Threshold
we recommend to use the
Fraction Preview
Upper Threshold
At high absorbance values the light intensity on the detector
is extremely low and consequently detector noise will be superimposed on the
detector signal. In this case the detector noise might trigger fraction collection.
To avoid false fraction collection triggering, we suggest setting an
Upper
Threshold
well below the limit where this false triggering effect might occur. As
soon as the detector signal exceeds the
Upper Threshold,
settings for Up Slope or
Down Slope will be ignored until the signal drops again below the Upper
Threshold.
When using more than one peak detector fraction collection can be triggered
either when
all selected peak detectors
detect a peak or when
at least one selected
peak detector
detects a peak basing on the settings in the
Peak Detectors
table
above.
If an MSD is used for mass-based fraction collection,
Use MSD for mass-based
fraction collection
must be checked.
Timetable
The
Timetable
can be used to program changes in the Fraction Trigger Mode
during the analysis by entering a time in the
Time
field and appropriate values
in the fields of the timetable.
Trigger Mode
Off, Peak Based and Time Based can
be selected. If the Off is selected, no fractions are collected.
