Towards greener stationary phases : thermoresponsive and carbonaceous chromatographic supports [Elektronische Ressource] / Irene Tan. Betreuer: Markus Antonietti

Irene Tan

Informations

• Publié par: universitat_potsdam
• Publié le: 01 janvier 2011
• Nombre de lectures: 15
• Langue: English
• Poids de l'ouvrage: 4 Mo

Extrait

Max Planck Institut für Kolloid und Grenzflächenforschung


Towards Greener Stationary Phases: Thermoresponsive and
Carbonaceous Chromatographic Supports


Dissertation


zur Erlangung des akademischen Grades
“doctor rerum naturalium”
(Dr. rer. nat.)
in der Wissenschaftsdisziplin Kolloidchemie





eingereicht an der
Mathematisch-Naturwissenschaftlichen Fakultät
der Universität Potsdam




von
Irene Tan This work is licensed under a Creative Commons License:
Attribution - Noncommercial - Share Alike 3.0 Germany
To view a copy of this license visit
http://creativecommons.org/licenses/by-nc-sa/3.0/de/










































Published online at the
Institutional Repository of the University of Potsdam:
URL http://opus.kobv.de/ubp/volltexte/2011/5313/
URN urn:nbn:de:kobv:517-opus-53130
http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53130 ii
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“Du must das Leben nicht verstehen,
dann wird es werden wie ein Fest.”

Rainer Maria Rilke (1875-1926)
iii
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TABLE OF CONTENTS


1 INTRODUCTION ....................................................................................................... 1

2 THEORY AND BACKGROUND .............................................................................. 5

2.1 Stationary Phases for High Performance Liquid Chromatography ........................... 5

2.1.1 Silica Monoliths ...................................................................................................... 5

2.1.2 Polymer Immobilized on Silica Stationary Supports ............................................... 7

2.1.3 Porous Graphitic Carbon .......................................................................................... 9

2.2 Stimuli Responsive Polymers .................................................................................... 10

2.2.1 Thermoresponsive Polymers .................................................................................. 11

2.3 Controlled/ Living Radical Polymerization Techniques .......................................... 13

2.3.1 Reversible Addition Fragmentation Chain Transfer Polymerization .................... 14

2.3.2 Atom Transfer Radical Polymerization ................................................................. 16

2.4 Hydrothermal Synthesis of Biomass Derived Carbonaceous Materials................... 18

3 CHARACTERIZATION METHODS ........................................................................ 21

3.1 Nitrogen Sorption ..................................................................................................... 21

3.2 Electron Microscopy ................................................................................................ 23

3.3 High Performance Liquid Chromatography ............................................................. 25

4 RESULTS AND DISCUSSION ................................................................................. 30

4.1 Modification of Silica Monoliths with Thermoresponsive Polymers for
Chromatography ...................................................................................................... 30

4.1.1 In-situ Grafting of PEGylated Copolymer to Silica Monoliths ............................. 31

4.1.2 Synthesis and Characterization .............................................................................. 32

4.1.3 Chromatographic Characterization ........................................................................ 40

4.1.3.1 Effect of Temperature on the Performance of the Column ................................. 42

4.1.3.2 Effect of Grafting Density on the Performance of the Column ........................... 45 iv
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4.1.3.3 Effect of Molecular Weight of Grafted Copolymers on the Performance of
the Column.......................................................................................................... .50

4.1.3.4 Effect of Varying Comonomers on the Performance of the Column .................. 52

4.1.3.5 Performance of the Column in the Separation of Proteins .................................. 53

4.1.3.6 Determination of the Hydrophobicity of the Monolithic Columns ..................... 54

4.1.3.7 Effect of Polymer Type on the Performance of the Column ............................... 56

4.1.4 Summary and Outlook ........................................................................................... 63

4.2 Biomass Derived Carbonaceous Materials for Chromatography ............................. 65

4.2.1 Hydrothermal Carbonization and the Incorporation of Functional Monomers ..... 66

4.2.2 Synthesis and Characterization .............................................................................. 68

4.2.3 Chromatographic Characterization ........................................................................ 83

4.2.4 Summary and Outlook ........................................................................................... 89

5 CONCLUSION ........................................................................................................... 91

6 APPENDIX ................................................................................................................. 97

7 REFERENCES ......................................................................................................... 109

1 INTRODUCTION


th
Dating back to the 4 century, pharmacology is known as the oldest discipline in health
sciences. Humans back then had already formulated cures for various illnesses; for example,
plants had been known to be used as remedies for as long as 60,000 years. How these
remedial properties function had been a topic that was redefined over centuries, starting with
the traditional beliefs of Hippocrates and Galen to modern theories and principles of drug
1action that govern today’s origin of pharmacology . One principle states that each remedy has
an identifiable essence that is obtained from the natural product by chemical extraction. Till
recent times, the separation of biological compounds such as proteins and enzymes is still
important in order to study their properties individually for various applications in life
sciences. Thus, in the last century, a huge research area was dedicated to this field.

Conventionally, biomolecules are separated by electrophoresis and liquid chromatography.
Electrophoresis is commonly used for separating biological macromolecules such as proteins
2
or small nucleic acids (DNA, RNA, oligonucleotides) under denaturing conditions . In liquid
chromatography, biomolecules can be separated with reversed phase liquid chromatography
3-5 6, 7(RPLC) , ion-exchange chromatography (IEC) or hydrophobic interaction
8-10chromatography (HIC) . Some trends accompanying current ‘state of the art’ techniques in
the development of high performance liquid chromatography (HPLC) are mentioned below.

‘Normal’ phase (NP) HPLC is one of the first chromatographic techniques developed, with a
hydrophilic surface chemistry using underivatized silica or alumina having a high affinity for
hydrophilic compounds. However, it is not commonly used due to its limitations in complex
bioseparation schemes like in proteomics as the use of purely non-polar solvents is employed.
Besides factors related with the high costs and less availability of organic solvents
(acetonitrile), non-specific interactions on normal phase columns cause the retention and
separation of highly hydrophilic and uncharged compounds to be inefficient. These
compounds also face solviphilic problems in non-polar mobile phases.

Since the 1970s, ‘reversed’ phase (RP) HPLC accounts for the vast majority of analyses
performed in liquid chromatography. It is any chromatography method that uses a non-polar
stationary phase; for example, by introducing alkyl chains bonded covalently to unmodified
polar silica support surface, reversing the order of elution compared to NP-HPLC. This Introduction 2
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