Item – Theses Canada

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OCLC number
56965408
Link(s) to full text
LAC copy
LAC copy
Author
Cubero Herrera, Lisandra,1975-
Title
Enhanced fluorescence detection of carboxylic acids with 1-pyrenemethanol and 9-anthracenemethanol.
Degree
M. Sc. -- Dalhousie University, 2003
Publisher
Ottawa : National Library of Canada = Bibliothèque nationale du Canada, [2004]
Description
2 microfiches.
Notes
Includes bibliographical references.
Abstract
This thesis describes the application of two fluorescent labels, 1-pyrenemethanol and 9-anthracenemethanol, for the selective and sensitive determination of analytes possessing a carboxyl group. The fluorescent derivatives were separated by reversed-phase (C 8) HPLC in 25 minutes using a solvent system of acetonitrile/water. Three different excitation sources, a Nd(YAG) laser ([lambda]exc 266 nm), a He-Cd laser ([lambda]exc 325 nm) and an Agilent 1100 Diode Array detector ([lambda]exc 250 nm), were used to determine detection limits, sensitivity and linearity. The instrument response was studied using the esters of nonanoic acid with both alcohols, as model compounds. Both of them could be detected down to 6 fmol for a 20[mu]L injection using 250 nm as excitation wavelength. The sensitivity of 9-anthracenemethyl nonanoate is around three times that of 1-pyrenemethyl nonanoate. Similar detector responses were obtained for other aliphatic acid derivatives. The optimum conditions under which carboxylic acids are converted into esters with both alcohols were studied, including reaction temperature, reaction solvent, reaction time and reagent/total acid ratio. The reaction reproducibility, detection limit, linearity and derivative stability were determined under the optimized derivatisation conditions. Around an 80% conversion of carboxylic acids into esters with both alcohols was obtained when the derivatisation reaction was carried out in dichloromethane at 44°C for 30 minutes. The reaction detection limit, for a 20[mu]L injection, is 1 * 10 -9 M for the esters of 1-pyrenemethanol and 2 * 10 -9 M for the derivatives of 9-anthracenemethanol. Application of one of these methods to the analysis of carboxylic acids in environmental samples is also described. Carboxylic acids were encountered predominantly in the vapor phase at concentrations ranging from 0.2 to 49 ng/m3.
ISBN
0612836711
9780612836716