PDA-100 Photodiode Array Detector
4-6
Doc. 031644-02 9/03
4.4
Drifting Baseline
•
Fluctuations in ambient temperature
Make sure the PDA-100 installation site temperature remains consistent.
Allow at least 6 cm (2.4 in) clearance behind the PDA-100 for ventilation.
Check that the flow cell inlet tubing is routed through the heat exchanger (see
Figure 2-4) and is correctly connected to the inside front panel (see
Figure 5-3). Check that solvent flow is directed to the cell inlet and out the
cell outlet.
Select a reference wavelength (see Section 3.4).
•
New lamp not burned in
After installing a new lamp, allow from 8 to 24 hours for the lamp to stabilize.
•
Lamp cover, flow cell cover, or front panel is missing
Do not operate the PDA-100 unless the lamp cover, flow cell cover, and front
panel are in place; optical components are sensitive to temperature and light.
•
Flow cell heat exchanger not in place
Check that the flow cell inlet tubing is threaded through the tubing guide on
the lamp cover and secured in place with the tubing bracket (see Figure 5-1).
•
Lamp not stabilized
The lamps usually require 20 to 30 minutes to stabilize. For sensitive
applications work or for detector validation, allow at least 2 hours for the
lamps to stabilize. After installing a new lamp, allow from 8 to 24 hours for
the lamp to stabilize.
After changing mobile phases, allow 20 to 30 column volumes for the system
to stabilize.
•
Leaking flow cell
Tighten fittings; if the cell continues to leak, replace it. Also, check that the
backpressure on the cell does not exceed the specification (see Section A.5).
•
Inappropriate reference mode selected
Dionex recommends selecting a reference wavelength (active reference
mode) for gradient analyses and turning off the reference wavelength for
