Agilent Technologies G7117C, Руководство пользователя

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Agilent InfinityLab LC Series Diode Array Detectors User Manual 100
5 Optimizing the Detector
Optimizing the Detector Regarding to the System
which allows the chromatographic peaks to be accurately drawn. As with most
analytical determinations groups of readings are effectively averaged to reduce
error in the result. The detector bunches raw data points and produces the output
signal data at the required data collection rate by an electronic filtering process. If
the resulting data rate is too slow (over filtering) the peak heights will be reduced
and the resolution between them reduced; too fast and the data is noisier than it
need be to accurately profile narrow peaks.
The
peak width setting in the detector allows the user to correctly set these
parameters without needing any knowledge other than sight of the
chromatogram integration results to see how wide the peaks are. The peak width
setting should be set for the narrowest peak width observed in the
chromatogram. If it is set too wide it will make the peaks appear lower in height
and wider (and potentially less resolved) and if it is set too narrow it will increase
the baseline noise unnecessarily. Essentially the software uses this value to set
the data collection rate such that it collects enough data points over the
narrowest peaks and it is aiming for 15 to 25 points across a peak. The 1290
Infinity DAD can collect at a maximum up to 240 Hz if required which would allow
enough data points to be collected over a peak that is only 0.1 s wide. The
response time setting is another way of indicating how this filtering is set. It is
measured in seconds and is about one-third of the peak width value (which is
measured in minutes). It effectively shows how quickly the plotted signal
responds to a step change in the input signal.
NOTE
The full spectra is not available under all conditions.
Based on the data points, the scan data rate is reduced, see
Table 19 on
page 100 and Table 20 on page 101.
Table 19 Peak Width — Response Time — Data Rate (G7117B)
Peak width at half
height [min]
1
Response
[s] Signal data
rate [Hz] Scan data rate
[HZ]
≤ 126 pts/scan
Scan data rate
[HZ]
≤ 251 pts/scan
Scan data rate
[HZ]
≤ 501 pts/scan
Scan data rate
[HZ]
>501 pts/scan
< 0.00078125 0.0078125 240 240 80 40 20
> 0.00078125 0.015625 240 240 80 40 20
> 0.0015625 0.03125 160 160 80 40 20
> 0.003125 0.0625 80 80 80 40 20
> 0.00625 0.125 40 40 40 40 20
> 0.0125 0.25 20 20 20 20 20
> 0.025 0.5 10 10 10 10 10