Enhanced selectivity and detectability in absorption and fluorescence methods based on polarization modulation

dc.contributor.advisor Edward S. Yeung
dc.contributor.author Christensen, Patrice
dc.contributor.department Chemistry
dc.date 2018-08-16T12:14:29.000
dc.date.accessioned 2020-07-02T06:13:47Z
dc.date.available 2020-07-02T06:13:47Z
dc.date.copyright Mon Jan 01 00:00:00 UTC 1990
dc.date.issued 1990
dc.description.abstract <p>Polarization properties of light can be exploited to develop more selective spectroscopic methods of chemical analysis. Modulation of polarization coupled with lock-in detection provides a powerful detection scheme with improved detectabilities. This dissertation demonstrates the importance of optical design in systems utilizing polarization modulation. In Chapter II, optimization of modulation frequency and efficiency and simplification of optical design led to a 10-fold improvement in the detectability for sodium atoms by laser polarization spectroscopy. The limit of detection for sodium atoms by this method is 2 ng/L. The increased S/N at 150 kHz allowed operation in the dispersion mode and subsequently provided linear calibration curves;Chapters III and IV present the first studies of fluorescence-detected circular dichroism (FDCD) for on-column detection in capillary electrophoresis (CE). Detection by direct fluorescence (FL) is carried out simultaneously and provides a convenient means of evaluating the FDCD performance. Modulation efficiency and balance and preservation of desired polarization are discussed in detail and are shown to have great influence on the selectivity attainable by FDCD. Among techniques that sense optical activity, FDCD provides superior detectability on an absolute scale because it is suitable for picoliter detection volumes. Optical activity signals were observed for riboflavin (LOD = 0.2 fmol) and for less than 50 fmol of some fluorescein isothiocyanate-amino acid derivatives (FTC-amino acids) by FDCD/FL-CE.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/9487/
dc.identifier.articleid 10486
dc.identifier.contextkey 6360027
dc.identifier.doi https://doi.org/10.31274/rtd-180813-9195
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/9487
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/82590
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/9487/r_9110489.pdf|||Sat Jan 15 02:33:30 UTC 2022
dc.subject.disciplines Analytical Chemistry
dc.subject.keywords Chemistry
dc.subject.keywords Analytic
dc.subject.keywords Chemistry
dc.title Enhanced selectivity and detectability in absorption and fluorescence methods based on polarization modulation
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 42864f6e-7a3d-4be3-8b5a-0ae3c3830a11
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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