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3.4
Optimizing Detector Performance
The performance of the Dionex PDA can be optimized by careful selection of key
operating parameters. This section defines these parameters, describes how they
interact, and offers guidelines for selecting them. The table below summarizes the
topics discussed in this section.
Operating Parameter
Flow cell material
Rise time
Data collection rate
Sample wavelength
Bandwidth
Reference wavelength
Reference bandwidth
Bunch width
Step*
Average*
Negative absorbance
*
Set automatically by Chromeleon 6.8; not available in Chromeleon 7
Flow Cell Material
The flow cell material must be chemically compatible with the mobile phases and
analytes of interest.
Strong bases can etch the fused silica windows of the flow cell. If the
mobile phase is a base, make sure the mobile phase concentration
does not exceed 0.1 M. If the concentration of the base is greater than
50 mM, disconnect the separator column and flush the system with
deionized water for 5 minutes at 1.0 mL/min immediately after the
analysis. If strong base remains in the cell for 1 to 2 days, the cell
windows may need to be replaced.
Do not use a PEEK flow cell with normal phase or chlorinated
solvents; these solvents will damage the cell.
Doc. 065378-01 1/12
3 • Operation and Maintenance
Performance Characteristics Affected
Chemical compatibility
Peak resolution, sensitivity, baseline noise
Peak resolution, disk space
Sensitivity, linearity
Sensitivity vs. baseline noise
Baseline drift
Baseline noise, baseline drift
Spectral resolution, peak match, disk space
Baseline noise, rise time, data collection rate, disk space
Rise time, data collection rate
Peak detection, baseline noise, linearity
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