Thermo Scientific Vanquish VF-D20 Operating Manual page 105

Filter Constant
Vanquish Charged Aerosol Detectors Operating Manual
When you select a data collection rate, observe the following guidelines:
•
In general, each peak should be defined by at least 20 data points.
For chromatograms with co-eluting peaks or low signal-to-noise
ratios, 40 data points per peak are recommended.
•
If all peaks are relatively wide, select a lower data collection rate (for
example, 1.0 Hz). This saves disk space and allows for a faster display
of data in the Chromeleon software.
•
If the data collection rate is too low, the start points and end points
of peaks will not be determined accurately.
•
If any peaks of interest are less than a few seconds, select a higher
data collection rate (10.0 Hz, for example). If the data collection rate
is too high, data files may need more disk space and post-run
analyses may require more processing time.
•
Consider also the filter constant when setting the data collection
rate. Set the two parameters together in order to optimize the
amount of data points collected, and reduce short-term noise, while
still maintaining peak height, symmetry, and resolution. See below.
The filter constant is applied to the output current to electronically
reduce the baseline noise during the analysis.
When setting a filter constant, observe the following:
•
A small filter constant, such as 0.2 seconds, removes little baseline
noise.
• A large filter constant, such as 10.0 seconds, smoothes the baseline
significantly.
6 • Operation
Page 105