Page 335 - Tandem Techniques
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Figure 8.23
Diagrams of the Phase Separator.
The membrane is fabricated from two materials. The inner layer comprises an unsupported 1 µm pore
Teflon sheet. This sheet is sandwiched between two outer sheets, each of 1 µm pore Teflon, supported
by non-woven polypropylene membranes. The membrane is assembled so that the supporting non-
woven polypropylene membranes are on the outer surfaces. The infrared cell is a modified form of the
Spectra-Tech Inc. de-mountable flow cell, fitted with windows of either calcium fluoride or zinc
selenide. The system appears to function well and satisfactory spectra are shown that had been obtained
from 100 µg of material. Although an improvement on the sensitivity obtained by Conroy and Griffiths,
it is still relatively poor compared with that obtained with the rotating disk interface.
More recently, the extraction system has been extended further by Somsen et al. [23]. These authors
have developed a segmented flow concentrator that causes little or no band dispersion, and thus
conserves the resolution
