Page 286 - Tandem Techniques

Page 270

The flow cell, for maximum fluorescence light sensitivity, should be as large as possible. However, all
post column volumes must be minimized to prevent peak dispersion and to preserve the peak shape. In
practice, the cell volume was chosen to be 5 µl, as compromise between these conflicting demands. A
diagram of the HP flow cell is shown in Figure 7.11.

Figure 7.11
The HP Fluorescence Spectrometer Flow Cell
Courtesy of the Hewlett Packard Corporation
The cell is made from a quartz tube with stepped quartz windows. The optics are arranged such that the
whole of the cell volume is illuminated, and thus all the sample can be excited and will fluoresce.
Temperature stability is achieved by passing the eluent through a heat exchanger, thus helping to
establish base line stability. The cell windows are spring loaded against their sealing faces by a pressure
of about 1200 p.s.i., to protect the cell from rising column back-pressure