Waters 2998, Обзор и руководство по обслуживанию

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December 5, 2017, 715004753 Rev. B
Page 17
Figure 1–2: Absorbance as a function of concentration
1.2 Flow cell operating principles
The Waters
®
TaperSlit™ flow cell used in the PDA detector renders the detector baseline
essentially insensitive to changes in mobile phase refractive index (RI). RI changes occur during
gradient separations or result from temperature or pump-induced pressure fluctuations.
To achieve RI immunity, a combination of a spherical mirror, a lens at the entrance of the flow cell,
and a taper to the internal bore of the flow cell prevents light rays from striking the internal walls of
the flow cell. The Waters TaperSlit flow cell, so-called because of the shape of the flow cell exit
face, matches the shape of the spectrograph slit. Compared to a conventional flow cell with a
cylindrical shape, the PDA detector achieves higher light throughput for a given spectral resolution
with the TaperSlit cell design.
Figure 1–3: Comparison of flow cell characteristics:
Concentration
Absor
bance
Ideal
Actual
Linear range for
analyte
Window
Window
UV light
Conventional flow cell:
TaperSlit analytical flow cell:
Window
Lens
UV light