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Exit Seminar "Mass Spectrometric Analysis of Lignin Model Compounds: Fundamental Investigations of Ionization and Supramolecular Interactions for Lignocellulosic Biomass Applications

ech275 — Tue, 08 Mar 2022 15:11:01 +0000

Exit Seminar "Mass Spectrometric Analysis of Lignin Model Compounds: Fundamental Investigations of Ionization and Supramolecular Interactions for Lignocellulosic Biomass Applications ech275 Tue, 03/08/2022 - 10:11 am

Graduate Student Profile

Abstract: Lignocellulosic biomass is pivotal in the development of renewable energy sources and materials essential to mitigate the exploitation of fossil fuels causing environmental pollution issues. The conversion of biomass into fuel requires the hydrolysis of cellulose and a biproduct of this process is the isolation of lignin as biorefinery waste. Lignin is a complex high molecular weight polymer whose structure remains undefined and critically limits potential industrial applications of lignocellulosic biomass. The advancement of analytical methods for structural elucidation of lignin and its ensemble of phenolic compounds is therefore essential to advance this field. While a variety of analytical methods play an integral role in developing our understanding of lignin, only mass spectrometry can provide exact information on the substructure of lignin, the sequence of monolignols, and linkage types. In this dissertation, the supramolecular interactions of a variety of model lignin monomers and dimers are characterized to improve mass spectrometric analysis and potential applications of lignin as a renewable source of valuable phenolics. Mass spectrometry (MS) requires the conversion of analytes into detectable gas-phase ions, and the most widely used ionization technique for biological compounds is electrospray ionization (ESI). The primary challenge facing ESI-MS analysis of lignin is ionization because lignin compounds do not readily accept protons for positive mode analysis and negative mode analysis causes destabilization and in-source fragmentation. While protonation is unsuccessful, lithium adduction has recently been discovered as a promising method for ESI-MS sequencing of lignin compounds. Consequently, the gas-phase lithium cation basicity of synthetic monolignols and dimers were characterized by ESI-MS to improve sequencing techniques and future applications of lithium adduction. Lignin also presents a challenge in biomass processing due to its inhibition of the enzymatic hydrolysis of cellulose for biofuel production. Supramolecular guest-host interactions have the potential to isolate lignin compounds from biomass fractions through the formation of inclusion complexes and the development of selective materials. In this work a cyclodextrin host was selected based on its remarkable ability to encapsulate guest molecules and availability on the industrial scale. The binding strength between guest and host was evaluated for lignin model dimers with cyclodextrin by ESI-MS for comparison with our collaborators ITC and computational results. The retention of electrostatically bound complexes during the ESI-MS process and lithium adduct impacts are also extensively evaluated. Lignin compounds and metabolites additionally show biological activity, and therefore the separation of diastereomers is of interest for pharmaceutical applications. To advance biological studies, the success of chromatographic separations (HPLC) of lignin model dimers and their diastereomers is evaluated. The separative method is coupled to MS with post-column lithium adduction to identify lignin dimers. Novel determinations of lignin dimer partition coefficients are also presented, a measure of hydrophobicity important for biological studies and chromatographic method development. These fundamental characterizations of lignin model compounds are essential for the continued advancement of renewable energy and materials derived from lignocellulosic biomass.

Date:

Thursday, April 21, 2022 - 10:00 am - Thursday, April 21, 2022 - 11:00 am

Location:

CP-114B

Tags/Keywords:

#chemistry

chemistry seminar

Event Series:

ChemNews

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Read more about Exit Seminar "Mass Spectrometric Analysis of Lignin Model Compounds: Fundamental Investigations of Ionization and Supramolecular Interactions for Lignocellulosic Biomass Applications

��vlog�ٷ�� GSA Tailgating Event

ech275 — Wed, 17 Nov 2021 20:19:41 +0000

��vlog�ٷ�� GSA Tailgating Event ech275 Wed, 11/17/2021 - 03:19 pm

The Department of ��vlog�ٷ�� Graduate Student Association (GSA) would like to invite you to a tailgating event on Saturday, November 20 from 10:00am-11:30am on the Tobacco Research, Lawn 1. This event is co-hosted by the Sri Lankan Student Association. A grill and some non-alcoholic beverages will be available. If you choose to bring your own alcohol, you must remain in compliance with University Alcohol Policies.

The Tobacco Research, Lawn 1 is located on the corner of University Drive and Cooper Drive, directly adjacent to the Kentucky Tobacco Research and Development Center. You may view it on the campus map here.

We hope to see you there this Saturday!

Department of ��vlog�ٷ�� Graduate Student Association

Sri Lankan Student Association

Date:

Saturday, November 20, 2021 - 10:00 am - Saturday, November 20, 2021 - 11:30 am

Location:

Tobacco Research, Lawn 1

Tags/Keywords:

#chemistry

Event Series:

ChemNews

��vlog�ٷ�� Event

Read more about ��vlog�ٷ�� GSA Tailgating Event

Biological ��vlog�ٷ�� Seminar

jlva225 — Thu, 04 Sep 2014 12:51:36 +0000

Biological ��vlog�ٷ�� Seminar jlva225 Thu, 09/04/2014 - 08:51 am

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Note the change in time, date, and location.

Hope Cook will be presenting a seminar titled The pH Dependence of Photosystem II Oxygen-Evolving Complex Assembly.

Abstract: Photosystem II (PSII) research has gained interest in recent years due to the need for energy production. However the mechanisms of photosystem II photoassembly and water oxidation are not well understood. Therefore the main goal of my research was to understand photoassembly better by determining the pH dependence of oxygen evolving complex (OEC) assembly. These experiments could help to gain a better understanding of D1 (a subunit of photosystem II) degradation and PSII repair as well as determine the amino acid residues involved in the process. However, due to several issues with photoassembly there were some problems had to be addressed in order to perform this experiment. Therefore, we first had to optimize the process for depleting the cofactors from PSII (known as apo-BBY (PSII enriched particles) preparation) and photoassembly of PSII. This process took up most of my time in the lab so the pH dependence experiment was not fully completed and conclusions cannot be made based on the data obtained. Two side projects included in this research, was to understand the temperature dependence of water oxidation and to study non-converntional redox mediators in order to enhance the rate of oxygen-evolution. The combined data from all the experiments performed will lead to a better understanding of photosystem II as well as lead to better ways of studying photosystem II.

Course Instructor: Dr. Anne-Frances Miller

Date:

Friday, September 26, 2014 - 03:00 pm - Friday, September 26, 2014 - 03:50 pm

Location:

CP-114C

Event Series:

ChemNews

Read more about Biological ��vlog�ٷ�� Seminar

ChemNews

Exit Seminar "Mass Spectrometric Analysis of Lignin Model Compounds: Fundamental Investigations of Ionization and Supramolecular Interactions for Lignocellulosic Biomass Applications

����vlog�ٷ���� GSA Tailgating Event

Biological ����vlog�ٷ���� Seminar

��vlog�ٷ�� GSA Tailgating Event

Biological ��vlog�ٷ�� Seminar