General Guidelines For Detector Operation; Mobile Phases - Thermo Scientific Dionex UltiMate 3000 Series Operating Instructions Manual

UltiMate 3000 Series:
Fluorescence Detectors FLD-3100 and FLD-3400RS

4.6 General Guidelines for Detector Operation

The following sections offer general guidelines for detector operation. For information
about how to optimize the detector performance, see section 5.7 (→ page 77).

4.6.1 Mobile Phases

Mobile phase quality significantly affects detection limits and instrument performance. To
ensure optimal performance of the detector, observe the following guidelines:
• Prepare all mobile phases with HPLC-grade (or better) solvents, reagent-grade chemicals,
and filter HPLC-grade water. Usually, HPLG-grade solvents will provide good results.
As impurities in the solvents increase the baseline noise, you should use special
fluorescence-grade solvents, for example LiChrosolv
use fluorescence-grade solvents and water for Raman tests and instrument qualification.
• Degas all mobile phases before use and maintain them in a degassed state.
• Strong bases can etch the silica windows of the flow cell. Therefore, avoid the use of
mobile phases with a pH value > 9.5. In any case, disconnect the separation column and
flush the system with HPLC-grade water for 5°minutes at 1.0°mL/min immediately after
the analysis when alkaline solutions are used.
• Mobile phase pH affects not only the retention time of the separation, but the
fluorescence intensity and wavelength of the sample.
• When changing from a buffer to a different operating mobile phase, be sure the solvents
are miscible and will not induce precipitation of the buffers. Flush the cell with a buffer-
compatible solvent (in most cases, HPLC-grade water) immediately after the analysis. Do
not allow buffers to remain in the cell for extended periods.
For information about the properties of common used mobile phases, see section 10 in
Table 1 (→ page 123).
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Operating Instructions