DAD 6.1L/DAD 2.1L/MWD 2.1L user manual V6700, version 3.2
32
Optimizing the Detector
Data Rate
The data rate (or sampling rate) is the number of data points per second
(Hz) at which the detector transmits data to the computer.
Default Data Rate
The default data rate setting for the detectors is 1 Hz (see “Default Settings”
on page 27). The maximum data rate (digital signal) is 100 Hz. Lower data
rates store average data points. A 50 Hz data rate averages 2 points. A 10 Hz
data rate averages 10 points. The analog data rate is fixed at 12.5 Hz.
Optimizing the Data Rate
The optimal data rate depend on your application. Too few points across a
peak (short data rate) decrease detail and compromise reproducibility. Too
many points (high data rate) introduce noise into the system and the result-
ing files can become very large. Some general considerations are listed
below:
Each peak should be defined by 20–30 data points. For chromatograms
with co-eluting peaks or low signal-to-noise ratios, 40–50 data points per
peak are recommended.
If all peaks are relatively wide, select a slower data rate.
If any peaks of interest are less than a few seconds, select a faster data
rate.
If the data rate is too slow, the start and end points of the peaks are not
accurately determined. If the data rate is too fast, data files may occupy
excessive disk space and post-run analyses may require more processing
time.
Integration Time
Signal Level
The integration time influences the intensity of the signal and therefore the
sensitivity of the measurement. The larger the integration time, the higher
the intensity of the signal until the maximum sensor counts are reached.
Peak Width
Time Constant
Data Rate
[min]
[s]
[Hz]
<0.003
0.01
100
>0.007
0.02
50
>0.017
0.05
20
>0.033
0.1
10
>0.067
0.2
5
>0,167
0.5
2
>0,333
1
1
Fig. 28
noise with different data rates
