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Calibration, Optimization, And Deployment Of Ptr-Ms Instruments During The Airmap Project, Karl B. Haase

Doctoral Dissertations

Proton Transfer Reaction Mass Spectrometry (PTR-MS) is an increasingly popular technique for monitoring volatile organic compounds with high sensitivity and time resolution. This dissertation encompasses three different projects, sharing the common theme of expanding the knowledge and utility of the technique.

The first project focuses on elucidating the ion chemistry that occurs within the PTR-MS drift tube reaction chamber. The PTR-MS uses a differentially pumped skimmer to prevent excess water from the ion source from entering the drift tube reaction chamber. By placing a metering valve in between the skimmer region and the pump, it was possible to control the …

Chromatographic Studies And Analytical Methods Development For Selected Tetraazamacrocycles And Their Copper(Ii) Complexes, Ilia Terova

Doctoral Dissertations

Cu(II)-azamacrocyclic complexes are of current interest due to their potential application as copper-64 radioisotope-based imaging and therapeutic agents. The development of separation conditions is important in evaluating their purity as well as assessment of their physical properties including conditional formation constants, acid dissociation constants and lipophilicity, which can have a major bearing on the in vivo behavior of these complexes. This study evaluates the chromatographic properties of a series of copper (II) complexes of chelating cross-bridged tetraamine ligands with methanephosphonate arms having different ring sizes (12- and 14-membered) and different pendant arm moetics. Cu-CB-DO2POEt and Cu-CB-TE2POEt are two complexes with …

Volatile Organic Compounds In The New England Troposphere: Atmospheric Chemistry And Measurement Techniques, Jesse L. Ambrose

Doctoral Dissertations

Atmospheric measurements made at Appledore Island, Maine were used to investigate nighttime nitrate radical (NO3) chemistry and its significance for the nitrogen oxides (NOx = NO + NO2) budget in the Gulf of Maine region during the summer of 2004 International Consortium for Atmospheric Research on Transport and Transformation field campaign. Removal of NOx was strongly dependent on reactions of NO3 with biogenic volatile organic compounds and the fate of dinitrogen pentoxide (N 2O5). For three case studies, temporal profiles of NO 3 were calculated from measured parameters. Comparisons between measured and calculated NO3 mixing ratios highlighted significant uncertainties in …

Ratiometric Fluorescent Metal Ion Indicators Based On Functionalized Poly(N -Isopropylacrylamide), Jie Du

Doctoral Dissertations

A novel type of ratiometric fluorescent indicator based on the phase transition of a well-known stimuli-responsive polymer poly(N-isopropylacrylamide) (PNIPAM) is presented. The sensing mechanism involves the polymer conformational change resulting from charge neutralization by the analyte metal ions. The ultimate goal is to develop ratiometric fluorescent indicators for free Cu(II) in environmental water analysis.

The indicators are copolymers of N-isopropylacrylamide (NIPAM) with small percentages of fluorophores and ligand monomers. The charges on the ligands prevent PNIPAM from collapsing unless neutralized upon metal ion chelation. The polymer phase transition is transduced by either fluorescence solvatochromism or fluorescence resonance energy transfer (FRET), …

Measuring Paralytic Shellfish Toxins In Mussels From New Hampshire Coastal Waters Using Zwitterionic Hydrophilic Liquid Chromatography/Electrospray Mass Spectrometry, Lee Lee Chung

Master's Theses and Capstones

A liquid chromatography/mass spectrometry method (LC/MS) has been adapted from the literature to provide a rapid, direct and highly sensitive routine assays for several Paralytic Shellfish Poisoning (PSP) toxins, with detection limits in the ppb range for STX and its analog neosaxitoxin (NEO) and decarbamoyl saxitoxin (dcSTX). A high throughput sample clean-up aided in reducing the effects of the matrix. Method validation and stability studies have been performed to show that reliable results are produced by this LC/MS method. The LC/MS method was found to supplement the mouse bioassay with the ability to determine the levels and specific types of …