Chemistry, Department of

 

Date of this Version

Spring 5-2011

Comments

A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy,
Major: Chemistry, Under the Supervision of Professor David S. Hage. Lincoln, Nebraska: May, 2011

Copyright 2011 Raychelle M. Burks

Abstract

This work describes the first use and characterization of macrocyclic polyether (MP) modified sodium dodecyl sulfate (SDS) pseudostationary phases (PSPs) for use in micellar electrokinetic chromatography (MEKC), as well as the development of a presumptive chemiluminescence assay for peroxide-based explosives. In MEKC separation and detection, resolution is optimized by using various PSPs or by altering the properties of a single PSP using different class I or II modifiers. Class I modifiers target the PSP through direct interaction with micelles, while class II organic modifiers operate by altering the BGE. The of MPs 18-crown-6, 15-crown-5, and 12-crown-4 were used to modify SDS, with their effect on the SDS PSP and solute partitioning characterized using a linear solvation energy relationship (LSER) and select thermodynamic properties. Over two dozen solutes were used to probe the MP modified SDS PSPs, many of them nitro-based explosives (NBEs), precursors and/or additives to NBE compositions.

Easy-to-monitor presumptive assays are routinely used by forensic scientists, law enforcement and military personnel to screen for drugs of abuse and explosives. For peroxide-based explosives (PBEs), such assays are often indirect, monitoring the PBE precursor and degradation product hydrogen peroxide (H2O2) by utilizing peroxidase-based luminescence. As with most enzyme-based methods, peroxidase methods can be a challenge to integrate into field test kits. Presented here is an attractive alternative based on the H2O2 - acetonitrile - luminol (HPAL) chemiluminescence reaction. This assay requires four simple reagents and no instrumentation for the visual detection of commonly encountered PBEs (TATP and HMTD) as well as H2O2(l). Limits of detection were in the low mg range for PBEs and 4 µg/mL for H2O2(l). This HPAL assay can also act as a color test, with reaction solutions changing from colorless or white to yellow, probably due to the formation of 3-aminophthalate anion.

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