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dc.contributor.authorTso, Jerry
dc.date.accessioned2016-03-31T14:22:34Z
dc.date.available2016-03-31T14:22:34Z
dc.date.issued2011
dc.identifier.isbn9781124731971
dc.identifier.other879040471
dc.identifier.urihttp://hdl.handle.net/10477/47320
dc.description.abstractIn the first part of this work, simultaneous extraction of estrone (E1), 17β-estradiol (E2), estriol (E3), ethinylestradiol (EE2), and their glucuronated and sulfated metabolites in milk was optimized using solid-phase extraction (SPE). Two SPE cartridges in tandem were used, consisting of sorbents based on the hydrophilic-lipophilic balance and amine-functionalized packing materials. To monitor analyte loss at every step of the SPE procedure 14 C-labeled E2 was spiked into the milk sample and the radioactivity was monitored at all stages of the SPE. The optimized method described in this chapter can achieve recoveries ranging from 72% to 117% for the free estrogens (E1, E2, E3, and EE2), and 62% to 112% for seven conjugated metabolites. The three doubly conjugated, highly polar metabolites included in this study gave lower recoveries (≤ 43%) due to poor retention in SPE. Finally, commercial milk samples were analyzed for the presence of estrogens and their conjugated metabolites. Estrone (concentration range: 23-67 ng/L) was found to be the major free estrogen present in all milk samples. Estradiol was consistently observed in milk, but the concentrations were below the limit of detection (LOD of 10 ng/L), and no estriol and ethinylestradiol were detected. Several conjugated estrogen metabolites were identified, 17β-estradiol-3-glucuronide (71-289 ng/L), estrone-3-sulfate (60-240 ng/L), 17β-estradiol-3, 17β-sulfate (<LOD to 30 ng/L), and estrone-3-glucuronide (<LOQ of 25 ng/L). This method proved efficient in the simultaneous analysis of estrogens and their metabolites in milk. This work investigates the use of wrong-way-round (WWR) ionization to demonstrate that sulfonamides and tetracyclines can be analyzed at a high pH (10.4), allowing simultaneous analysis with free and conjugated estrogens. The WWR ionization was brought about by the ability of ammonium ions to protonate basic compounds in the gas phase even at high pH. Mass spectral data suggest that gas-phase chemical ionization induced by ammonium ions to form adducts [M + NH 4 ] + occurred, with the subsequent dissociation to the molecular ion [M + H] + . Almost all compounds have an increased signal-to-noise (S/N) ratio of [M + H] + for sulfonamides and tetracyclines when ionized in basic versus acidic mobile phases by direct injection (no column), indicating that detection limits were not compromised. This study demonstrates a successful application of WWR ionization for the simultaneous analysis of multiple classes of compounds in a single LC-MS/MS analysis. This method for analyzing free and conjugated estrogens along with sulfonamides and tetracyclines utilizes a single-step sample preparation by SPE was used to isolate and concentrate all analytes simultaneously. The analytical method was developed and validated for recoveries at 3 concentration levels for water and soil and produced recoveries of 42-123% and 21-105% respectively. Method detection limits ranged from 0.3 to 1.0 ng/L for water samples and 0.01 to 0.1 ng/g for soils. The method quantification limit ranged from 0.9 to 3.3 ng/L for water samples and 0.06 to 0.7 ng/g for soils. The single-point standard addition calibration procedure was validated across a linear range of MQL to 100 ng/L with 82% accuracy against a matrix matched standard curve. . Quantum dot nanoparticles continue to gain interest in the scientific and medical field, however their potential release into the environment has raised concerns. The toxicity of nanoparticles can be due to the release of toxic elements such as cadmium, selenium, and zinc, which are often used in the core/shell of the nanoparticles. The work here begins to explore coupling of capillary electrophoresis (CE) to inductively coupled plasma-mass spectrometry (ICP-MS) to attempt to differentiate free metal species versus intact quantum dot nanoparticles. The coupling of CE-ICP-MS was achieved by a dual capillary sleeve (CE and sheath flow) into a T-liquid junction grounded with a platinum electrode. A custom made concentric nebulizer was designed using polyetheretherketone and signal intensity was dependent on the inner diameter of the nebulizer and position of the capillary tip. The CE-ICP-MS analysis was performed on 10 ƒÝg/mL Cd standard resulting in a migration time of 4 min., where carboxyl QDs resulted in a migration time of 13.7 min. in a 5 mM ammonium acetate and 10 mM Tris buffer at a pH of 8 in separate injections. (Abstract shortened by UMI.)
dc.languageEnglish
dc.sourceDissertations & Theses @ SUNY Buffalo,ProQuest Dissertations & Theses Global
dc.subjectHealth and environmental sciences
dc.subjectPure sciences
dc.subjectBiological sciences
dc.subjectAntibiotics
dc.subjectEmerging contaminants
dc.subjectEstrogens
dc.subjectHormones
dc.subjectMilk
dc.subjectQuantum dot nanomaterials
dc.titleMethodologies for emerging contaminants in environmental and food matrices by liquid chromatography-tandem mass spectrometry and by capillary electrophoresis-inductively coupled plamsa-mass spectrometry
dc.typeDissertation/Thesis


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