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Proceedings Paper

On-line detection for capillary and packed-column supercritical fluid chromatography by direct-deposition SFC-FTIR
Author(s): Anthony S. Bonanno; Kelly L. Norton; Jyisy Yang; Peter R. Griffiths
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Paper Abstract

Compounds separated by supercritical fluid chromatography (SFC) can be identified by Fourier transform infrared spectrometry (FT-IR) after direct deposition (DD) onto an infrared transparent substrate. This methodology has been demonstrated as an off-line technique by several groups'3. A logical extension to this technique is to collect the spectra of the eluting species on-line. This is demonstrated using a commercial DD GC/FT-IR interface4 with minor modifications. The transfer line is replaced with an integral restrictor which acts as both pressure restrictor and transfer line. The tip of the restrictor is held about 75 mfrom a cooled zinc selenide window. Since carbon dioxide expands to a gaseous state upon decompression, it can be pulled away by a moderate vacuum, and the eluting species are trapped as small spots (about 100 jm diameter) on the cooled window. During a chromatographic run the window is translated such that shortly after deposition the spots pass through the focused beam of an infrared spectrometer. The radiation is collected by a Schwartzchild microscope objective and focused at an adjustable aperture by a field lens. The size of this aperture determines the effective size of the beam at the zinc selenide window. The fraction of the beam transmitted by the aperture is refocused onto the element of an MCT detector by a second Schwartzchild objective. Since the two objectives are identical, maximum sensitivity is achieved with a detector element the size of the trapped siots (100 j.m).

Paper Details

Date Published: 1 March 1992
PDF: 2 pages
Proc. SPIE 1575, 8th Intl Conf on Fourier Transform Spectroscopy, (1 March 1992); doi: 10.1117/12.56410
Show Author Affiliations
Anthony S. Bonanno, Univ. of Idaho (United States)
Kelly L. Norton, Univ. of Idaho (United States)
Jyisy Yang, Univ. of Idaho (Taiwan)
Peter R. Griffiths, Univ. of Idaho (United States)

Published in SPIE Proceedings Vol. 1575:
8th Intl Conf on Fourier Transform Spectroscopy
Herbert Michael Heise; Ernst Heiner Korte; Heinz W. Siesler, Editor(s)

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