Date on Master's Thesis/Doctoral Dissertation

12-2017

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Chemistry

Degree Program

Chemistry, PhD

Committee Chair

Nantz, Michael

Committee Co-Chair (if applicable)

Fu, Xiao-An

Committee Member

Zhang, Xiang

Committee Member

Conklin, Daniel J.

Committee Member

Richter, Natali B.

Author's Keywords

chemoselective reagents; carbonyl compounds; electronic cigarettes; microreactor

Abstract

Detection and analysis of trace level volatile aldehydes and ketones has become a significant research frontier because of the applicability for environmental monitoring and assessment, noninvasive diseases diagnosis, and in food safety assessment for the US Food and Drug Administration. The number of derivatization reagents for detection of aldehydes and ketones has increased considerably over the last decade. However, the majority of these derivatization reagents are not efficient in derivatizing unsaturated carbonyl compounds due to the presence of electron withdrawing groups adjacent to the reactive functional moieties making them insufficiently nucleophilic. The analysis of trace-level carbonyl compounds challenges existing analytical instrumentation because their concentrations are below current instrument limits of detection. This study shows for the first time the application of an innovative silicon-based microreactor for preconcentration of carbonyl compounds in electronic cigarette aerosols. The microreactor is coated with an aminooxy reagent, typically 4-(2-aminooxyethyl)-morpholin-4-ium chloride (AMAH) or 2-(aminooxy)-N, N, N-trimethylethanammonium iodide (ATM). The aminooxy functional group chemoselectively traps trace aldehydes and ketones generated by aerosolization of electronic liquids by means of oximation reactions. The aminooxy-carbonly adducts and unreacted aminooxy reagent are eluted from the microreactor using 150 μL of methanol followed by addition of an internal standard (for quantification) and then analyzed by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) or gas chromatography mass spectrometry (GC-MS), depending on the capture reagent used. Chapter 1 describes different methods of detection and analysis of volatile organic aldehydes and ketones in gaseous samples such as exhaled breath and electronic cigarette aerosols. Chapter 2 presents the analysis and quantification of carbonyl compounds in electronic liquid aerosols. Chapter 3 describes the kinetic studies of oximation reactions of the aminooxy reagents AMAH, ADMH and ATM. It also outlines the synthesis of a cationic hydrazine-based reagent for derivatization of aldehydes and ketones. Chapter 4 describes the quantification of nicotine in e-cig liquids and derived aerosols using both FT-ICR-MS and GC-MS. Chapter 5 provides the overall summary and future direction.

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