Analytical Chemistry Commons^™

Comprehensive Analytical Investigation Of Tetrahydro-4h-Chromene And Dihydropyridine Derivatives, Ryan J. Burk

Chemistry & Biochemistry Dissertations

Novel calcium channel blockers (CCBs) with dihydropyridine (DHP) or tetrahydro-4H-chromene moieties are often chiral, so effective enantiomer separation methods are needed for continued drug development. The purpose of this dissertation is to outline a comprehensive method development model for the chiral separations of DHPs and tetrahydro-4H-chromene derivatives. The scope of this dissertation is to address analytical challenges during initial synthesis, chiral separations, and data analysis during post-processing for this class of chiral compounds. The first section focuses on the method development strategies for separations of DHPs in the sub/supercritical fluid (SFC) and normal phase modes with the 2-hydroxypropyl-β-cyclodextrin stationary phase. …

Signal And Noise Analysis In An Undergraduate Instrumental Analysis Laboratory, Ken Overway

Chemistry Faculty Scholarship

Understanding the difference between signal and noise in a measurement is fundamental to analytical chemists. The typical instruments found in an undergraduate chemistry department can be used to teach this concept, as well as signal averaging, by giving students hands-on experience with measurements and data processing. This work presents an undergraduate laboratory module (homework and experiment) that provides specific instructions for using gas chromatographs, fluorometers, a nuclear magnetic resonance spectrometer, an atomic absorption spectrophotometer, and an infrared spectrometer to collect replicate measurements and a framework for calculating the noise level, baseline, signal level, signal-to-noise ratio (SNR), and the signal thresholds …

Identifying The Constituents Of Pyrolysis Oil Using Supercritical Fluid Chromatography- Fraction Collection (Sfc-Fc) And Gas Chromatography- Mass Spectrometry/Vacuum Ultraviolet Spectroscopy (Gc-Ms/Vuv), Sadid Morshed

2025 Fall Honors Capstones Projects - Archive

Plastic waste continues to accumulate as production increases and disposal methods remain insufficient. Even with recycling programs in place, much of the discarded plastic still ends up in landfills or waterways, eventually breaking down into harmful microplastics. One promising solution is the conversion of plastic waste into pyrolysis oil, which can also serve as an alternative feedstock for chemicals. Pyrolysis oil is produced by heating plastics to approximately 800 °C in the absence of oxygen, resulting in a complex mixture of hydrocarbons that includes paraffins, isoparaffins, olefins, naphthenes, and aromatics. Analyzing the amount of oxygen, nitrogen, and sulfur in these …

Surface Characterization Of Mixed-Mode Adsorbents Using Bet C-Constant Energy Scale, Dinah C. Lee

Seton Hall University Dissertations and Theses (ETDs)

Mixed-mode chromatography is a chromatographic method in which solutes interact with stationary phase through more than one interaction mode or mechanism. It is because of these multiple complex interactions, which makes it difficult to predict chromatographic behavior of analytes on Mixed-mode columns. In order to fully understand the retention mechanisms on Mixed-mode columns, the packing material properties must be well characterized since each characteristic may contribute to the overall chromatographic performance of the column. Many non-chromatographic and chromatographic techniques are available to characterize and compare Mixed-mode columns in terms of their interaction abilities, retentivity, surface chemistry, chemical properties and geometry. …

The Synthesis Of Deuterated Isohumulones For Use As Internal Standards In Lc-Ms Stable Isotope Dilution Assays, Patrick Gleason, Bruce Hamper Dr.

Undergraduate Research Symposium

Humulones are compounds that are prevalent in the hops flowers (Humulus Lupulus) used in beer brewing. These compounds undergo isomerization during the brewing process, and the resulting isohumulones are considered to be the primary contributors to the bitter flavors present in beer. As such, quantifying their presence, and the relative presence of their homologs(n-, co-, ad-), is of great importance in the characterization of beer. In this effort, one of the homologs of humulone (co) was isolated before being subsequently isomerized and deuterated for the purpose of analyzing beer by stable isotope dilution assay mass spectrometry(SIDA-MS). The addition of this …

Statistical Analyses Of Hemp Cannabinoid Test Results, Rachel J. Stegmeier

Senior Honors Projects, 2020-current

Cannabis sativa L. is a flowering plant used for recreational and industrial purposes that produces a class of compounds called cannabinoids. Industrial hemp is a strain of Cannabis sativa L. that has been propagated to have a low Δ 9 tetrahydrocannabinol (Δ⁹THC) and a high cannabidiol (CBD) content. With recent advancements in legislation, farms are now growing hemp for fiber, CBD production and other hemp derived product purposes but crops risk being destroyed if THC content levels exceed the current maximum legal limit of 0.3%. For the present study hemp samples were dried, ground, extracted with various alcohols, …

Chromatographic Studies Of Some Hormone And Metabolic Modulators Used For Doping In Sports, Ruth Marie Speidel

Online Theses and Dissertations

The World Anti-Doping Agency (WADA) is an international agency that monitors the use of Performance Enhancing Drugs (PEDs) in sports; their mission is “to lead a collaborative worldwide movement for doping-free sport” (Who We Are, 2022). For this mission, the WADA needs quick, sensitive, reproducible, and accurate methods for analyzing athletes’ biological fluids for possible PEDs. This research focuses on developing and validating simple, sensitive, rapid, and reliable gas chromatography- mass spectrometry (GC-MS) methods for the analysis of two hormone and metabolic modulators, toremifene and trimetazidine. Previously, there has been limited GC-MS methods used to analyze toremifene and trimetazidine. Quantification …

Investigation Of The Interface Reactions Of Ion Selective Electrode Membranes Using Chromatographic And Spectroscopic Analyses Of Erbium(Iii) Tetraphenylporphyrin, Alexis Rae Miller

Graduate Theses/Dissertations

Ion selective electrodes (ISEs) are analytical sensors that monitor the interactions between an ionophore within a polymeric membrane and ions in various solutions. The sensitivity and selectivity of ISEs is directly related to the chemical components. One type of ionopohore utilized in ISEs are metalloporphyrins. Metalloporphyrins have unique binding characteristics, which make them useful in sensors. The polymeric membranes that are synthesized and used in ISEs consist of a metalloporphyrin complex, polyvinyl chloride, and ortho-nitrophenyl octyl ether. The membrane unique to this project contains erbium (III) tetraphenylporphyrin as the metalloporphyrin ionophore. Various analytical techniques were applied in the investigation …

Online Ultra-High Performance Liquid Chromatography-Charge Transfer Dissociation-Mass Spectrometry (Uhplc-Ctd-Ms) Of Complex Mixtures Of Oligosaccharides, Praneeth M. Mendis

Graduate Theses, Dissertations, and Problem Reports (ETD)

Abstract

Online Ultra-High Performance Liquid Chromatography-Charge Transfer Dissociation-Mass Spectrometry (UHPLC-CTD-MS) of Complex Mixtures of Oligosaccharides

Praneeth M. Mendis

Complex carbohydrates make up more than half the biomass on earth, and they are crucial to a wide range of processes in living organisms. When polysaccharides and glycans are enzymatically digested into manageable units called oligosaccharides, they typically consist of 2-20 linear or branched sugar units. The detailed structural analysis of oligosaccharides assists in the identification of structural and chemical properties of the polymers from which they derive. Tandem mass spectrometry (MS/MS) is a key technique used in oligosaccharides structural characterization. Within …

Apparent Retention Volume Variation With Flow Rate Change In High Performance Liquid Chromatography, Susanne Buntz Erz

Seton Hall University Dissertations and Theses (ETDs)

Recent studies have demonstrated noticeable flow rate dependency of the chromatographic zone retention volume with respect to migration within the empty capillary. This appears to be the result of superposition of asymmetric lateral diffusion and of the laminar flow profile. Although these effects have been studied on empty capillaries, in the presence of the packed column, the retention shift may be insignificant relative to the adsorption-based retention of the analytes. In the case of fast and ultrafast HPLC with short capillary columns, the effect of extra-column caused variation in the analyte retention may constitute an increase of up to 120 …

Reactivity Of Ketyl And Acetyl Radicals From Direct Solar Actinic Photolysis Of Aqueous Pyruvic Acid, Alexis J. Eugene, Marcelo I. Guzman

Chemistry Faculty Publications

The variable composition of secondary organic aerosols (SOA) contributes to the large uncertainty for predicting radiative forcing. A better understanding of the reaction mechanisms leading to aerosol formation such as for the photochemical reaction of aqueous pyruvic acid (PA) at λ ≥ 305 nm can contribute to constrain these uncertainties. Herein, the photochemistry of aqueous PA (5-300 mM) continuously sparged with air is re-examined in the laboratory under comparable irradiance at 38° N at noon on a summer day. Several analytical methods are employed to monitor the time series of the reaction, including (1) the derivatization of carbonyl (C═O) functional …

Quantitative Analysis Of Acetylsalicylic Acid By Q-Nmr (Quantitative-Nuclear Magnetic Resonance Spectroscopy), Charles Flemming Jr.

All Student Theses and Dissertations

Quantitative analysis is an important step during pharmaceutical drug development. Currently, the pharmaceutical industry uses high performance liquid chromatography (HPLC) for quantitative analysis of organic compounds as the preferred technique. The proton nuclear magnetic resonance (NMR) technique has an inherent ability to quantify a given analyte and may be used to quantify organic compounds. Quantitative nuclear magnetic resonance spectroscopy (q-NMR) of acetylsalicylic acid (ASA) was conducted using tert-butyl alcohol (tert-butanol) as the internal standard and deuterated chloroform (CDCl₃) as the solvent. Preparations of ASA solutions in low and high concentration ranges, 1.0 mM – 10.1 …

Alignment For Comprehensive Two-Dimensional Gas Chromatography (Gcxgc) With Global, Low-Order Polynomial Transformations, Davis Rempe, Stephen Reichenbach, Stephen Scott

UCARE: Research Products

As columns age and differ between systems, retention times for GC x GC may vary between runs. In order to properly analyze chromatograms, it is often desirable to align chromatographic features between chromatograms. This alignment can be characterized by a mapping of retention times from one chromatogram to the retention times of another chromatogram. Alignment methods can be classified as global or local, i.e., whether the geometric differences between chromatograms are characterized by a single function for the entire chromatogram or by a combination of many functions for different regions of the chromatogram. Previous work has shown that global, low-degree …

Measurement Of Antioxidant Activity Toward Superoxide In Natural Waters, D. Whitney King, Emma Berger, Zachary Helm, Eleanor Irish, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

Antioxidants are a class of molecules that provide a protective function against reactive oxygen species (ROS) in biological systems by out competing physiologically important molecules for ROS oxidation. In natural waters, the reactivity of antioxidants gives an estimate of oxidative stress, and may determine the reactivity and distribution of reactive oxidants. We present an analytical method to measure antioxidant activity in natural waters through the competition between ascorbic acid, an antioxidant, and MCLA, a chemiluminescent probe for superoxide. A numerical kinetic model of the analytical method has been developed to optimize analytical performance. Measurements of antioxidant concentrations in pure and …

Molecular Approaches To Chromatography Using Single Molecule Spectroscopy, Lydia Kisley

Faculty Scholarship

No abstract provided.

Method Development And Analysis For Pharmaceuticals And Personal Care Products In Surface Water, Victoria Ruelas

All Capstone Projects

Pharmaceuticals and Personal Care Products (PPCP) in surface waters is a worldwide concern. Effluent from waste water treatment plants have tested positive for PPCP. Method development for a liquid chromatographic method was derived using columns with fused core technology. Analysis of spiked samples as direct injection and after solid phase extraction indicated detection of acetaminophen, caffeine, bisphenol-A and triclosan. Confirmation of acetaminophen, caffeine, bisphenol-A and triclosan was achieved using Agilent 1100 HPLC with Agilent MST Trap XCT. Solid phase extraction using Oasis HLB indicated reproducibility at 0.05ppm.

Optimization Of Polymer Separation By Gradient Polymer Elution Chromatography, Gideon R. Liem, Linda Nien-Hwa Wang

The Summer Undergraduate Research Fellowship (SURF) Symposium

High Performance Liquid Chromatography (HPLC) has been a versatile separation method for polymers for many years. Analysis of different polymers by HPLC is typically done by utilizing the differential solubility of the polymers by mixing a good solvent and an anti-solvent in various compositions. This method is called Gradient Polymer Elution Chromatography (GPEC). While GPEC has been used extensively, it commonly uses a linear gradient to separate components. Linear solvent gradients consume a lot of solvent and take a relatively long time (> 30 minutes) to complete. The goal of this study is to develop a step gradient from a …

Computational Methods For The Differential Profiling Of Triacylglycerols Using Rp-Hplc/Apci-Ms, Margaret Holbrook Broadwater

MUSC Theses and Dissertations

Reversed phase liquid chromatography with atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/APCI-MS) was employed for the analysis of natural mixtures of triacylglycerols. An integrated framework for data analysis, including preprocessing, statistical analysis and automated structure identification, was implemented in the R statistical program. Raw data stored as mzXML, mzData, or mzXML files are preprocessed using a series of steps for peak detection, chromatographic alignment, and normalization. Targeted and non-targeted feature selection steps are employed to filter the data for features that are relevant and informative for a particular biological question. Triacylglycerol structures are identified by evaluating relationships between the diacylglycerol …

Intragroup Separation Of Trivalent Lanthanides And Actinides For Neutron Capture Experiments In Stockpile Stewardship Sciences, Narek Gharibyan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Knowledge of low-energy cross sections for stable and unstable nuclei in neutron-, γ- and ion induced reactions is important in both the simulation and radiochemistry diagnosis of nuclear device performance. This dissertation explores extraction chromatography and ion chromatography methods for the intragroup separation of trivalent actinides and lanthanides in support of cross section measurements for isotopes of interest. For trivalent actinides, americium (Am(III)) and curium (Cm(III)), separation is necessary to assist in experiments related to the measurement of neutron capture cross section for ²⁴¹ Am and the production of ^{242 m} Am/^242g Am isomeric ratio. Extraction chromatography resins …

Synthesis And Analysis Of N-Acetyltyrosine-N-Ethyl Amide From N-Acetyl Yyrosine Ethyl Ester, Ravinder Reddy Akkuluri

All Capstone Projects

Amino acids gets oxidized when they are interacted with oxygen and light. And it is always difficult for the researchers to find and isolate a particular amino acid from a protein, unless they completely know how it behaves when interacted with light. For this we are synthesizing amide form of the amino acid which mimics the structure of a protein, and we induce light and find out the exact behavior of the particular amino acid. Here, the aim is to know the tyrosine interaction with light, so we synthesize amide form of tyrosine which is N-Acetyl tyrosine ethyl amide from …

Chromatographic Studies Of Drug-Protein Binding In Diabetes, Kathryn (Krina) S. Joseph

Department of Chemistry: Dissertations, Theses, and Student Research

Drug-protein binding can have a dramatic impact on the distribution and metabolism of a drug. This manuscript describes the use of high-performance affinity chromatography to examine the binding of various compounds to human serum albumin (HSA) in normal and diabetic disease states. The first study examined the use of four coumarin compounds as possible alternatives to warfarin as a probe for Sudlow site I on HSA. High-performance affinity chromatography and immobilized HSA columns were used to compare and evaluate the binding properties of these probe candidates. It was found from this group that 4-hydroxycoumarin was the best alternative to warfarin …

Arsenic Speciation Analysis Of Biological Fluids : A Study Of Liquid Chromatography Coupled To Analytical Atomic Spectrometric Instrumentation, Kanna Ito

Legacy Theses & Dissertations (2009 - 2024)

Arsenic exists as many different chemical forms including inorganic, methylated and dietary species. The toxicity of these species varies: some are highly toxic and can cause adverse health effects in many parts of the body; others are considered relatively non-toxic. Monitoring arsenic exposure is usually accomplished by its direct measurement in biological fluids. Urine is the specimen of choice for assessing arsenic exposure, because of its short biological half-life in blood. There have been very few studies of arsenic species in blood, yet such research can provide valuable information on arsenic distribution and its metabolism in the body.

Chemistry Of Zirconia And Its Bioanalytical Applications, Oge Anazia

Masters Theses & Specialist Projects

This research studies the chemical nature of zirconia and the complex surface chemistry of zirconia in order to better comprehend its behavior under chromatographic conditions. This research shows how the physical and chemical properties of zirconia depend strongly on the thermal treatment during synthesis. The morphology of the samples was also studied. The absorption capability of Adenosine Triphosphate (ATP) on zirconia was also monitored and spectrally characterized.

The results of this research showed how the properties of zirconia vary with thermal treatment. It was observed that the zirconia prepared at a higher temperature had lower surface area, lower pore size …

Studies On The Amylolytic Breakdown Of Damaged Starch In Cereal And Non-Cereal Flours, Karen Bailey

Masters

The term starch damage refers to a number of changes to the starch granule structure, which are detectable by different analytical techniques. Damaged starch is the substrate for amylases, which in turn provides carbohydrates that are used in the production of certain foods and food ingredients; as a result, therefore, determination of levels in flours is a procedure carried out routinely by many manufacturers of starch based products. Enzymatic assay methods emulate the susceptibility of damaged starch granules to enzymatic attack. The first aim of this study was to evaluate enzymatic methods(1,2) to determine damaged starch in wheat flours and …