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4
Xcalibur Diagnostics for the PDA Detector
Adjusting the Light Throughput with the Xcalibur Data System
Adjusting the Light Throughput with the Xcalibur Data System
42
Accela PDA Detector Hardware Manual
The first time that you adjust the attenuators, you must create a display method. After you
create the method for adjusting the attenuators, save it with a name that you can associate
with adjusting the attenuators and store it for future use.
Decreasing light throughput increases baseline noise. Increasing light throughput can saturate
the diode array. When the array is saturated, the response from the PDA detector is a flat
baseline.
During the deuterium lamp's lifetime of approximately 2000 hours (see
Detector Noise"
on
page
light output from the deuterium lamp decreases and whenever you do the following:
• Replace either lamp (see
• Replace the LightPipe flowcell (see
• Change the configured diode array scan rate (see
Configuration"
on
page
Tip The integrated light intensity viewed on the Display page is a function of the light
throughput to the diode array and diode array scan rate. When you change the diode array
scan rate, you must adjust the light throughput.
• If you increase the diode array scan rate (for example, from 20 Hz to 80 Hz), you
must increase the light throughput to achieve the same intensity counts.
• If you reduce the diode array scan rate (for example, from 80 Hz to 20 Hz), check the
intensity counts, and if necessary reduce the light throughput to avoid saturating the
array.
Adjusting the position of the attenuator tabs changes the light throughput to the diode
array: up increases and down decreases the light throughput to the diode array (see
Figure 20
on
page
25).
To adjust the attenuators while viewing the light intensities
1. Prepare the PDA detector to monitor an intensity scan (see
to Monitor Lamp Performance"
2. If you have not already done so, create a display method that scans from diode 2 to diode
511 with a diode step of 1 and that displays the default discrete channel wavelengths
(see
"Creating a Display Method to View Light Intensity"
5), the lamp's light output decreases. Adjust the attenuators as the
"Replacing the Lamps"
"Installing the LightPipe Flowcell"
28)
on
page
38)
"Lamp Lifetime and
on
page
89)
on
"Thermo Foundation Instrument
"Preparing the PDA Detector
on
page
38).
page
17)
Thermo Scientific
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