Virtual chromatography for the effective method development in liquid chromatography of polymers [Elektronische Ressource] / vorgelegt von Mubasher Ahmed Bashir

Bashim

Informations

• Publié par: technischen_universitat_darmstadt
• Publié le: 01 janvier 2007
• Nombre de lectures: 21
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

Virtual Chromatography for the Effective Method Development in
Liquid Chromatography of Polymers

Vom Fachbereich Chemie
der Technischen Universität Darmstadt

Zur Erlangung des akademischen Grades eines
Doctor rerum naturalium (Dr. rer. nat.)


genehmigte
Dissertation

vorgelegt von


Mubasher Ahmed Bashir
aus Rabwah (Pakistan)



Berichterstatter: PD Dr. Harald Pasch
Mitberichterstatter: Prof. Dr. Florian Müller-Plathe
Tag der Einreichung: 12.12.2006
Tag der mündlichen Prüfung: 29.01.2007

Darmstadt (2007)
D17

In the name of Allah, the Gracious, the Merciful



















































To my parents, wife and sweet little daughter


Prime thanks to Almighty Allah, the Lord of all worlds, Who created circumstances
to bring me at this level.
I am particularly grateful to PD Dr. H. Pasch who provided me the opportunity to
join his group and for his support during my stay at DKI. I am also thankful for the
liberty he gave to approach him.
I have a deep sense of gratitude for Dr. Wolfgang Radke who assigned me this
challenging and interesting research topic, which broadened my knowledge to a
considerable extent. I feel obliged for his excellent supervision, kindness, and
invaluable guidance to carry out the present research work. I will always remain
indebted to him. I also thank him for translating the summary of this thesis into
German language.
I would like to mention the contributions of Dr. Adele Brüll for providing some of
experimental data included in this thesis and of Dr. Iván García Romero who
provided the copolymer samples. I am thankful for their cooperation. I also
appreciate Dr. Tibor Macko for his moral support, compliments and optimistic
discussions.
My heartiest thanks to my group mates Karsten Rode, Karl-Heinz Spriestersbach,
Christian Heinz, Christoph Brinkmann, Dr. Wolf Hiller, Dr. Robert Brüll, Daniela
Knecht, Christel Hock and others for their broadmindedness and fair attitude towards
me. I am thankful for their help in everyday matters.
My special thanks go to my parents for their late night prayers and sacrifices in
bringing me to this stage in life. I am particularly thankful to my wife and little
daughter for their loving company. I also acknowledge the support of my uncles
Prof. Idrees Ahmad and Dr. Riaz Akber at the crucial times during my education
career.
Mubasher Ahmed Bashir





























Diese Arbeit würde am Deutschen Kunststoff-Institut unter Leitung von
PD Dr. H. Pasch in der Zeit von April 2003 bis Dezember 2006 durchgeführt.


Veröffentlichungen
Publikationen:
1. Mubasher A. Bashir, Adele Brüll, Wolfgang Radke
“Fast determination of critical eluent composition for polymers by gradient
chromatography”
Polymer, Volume 46, Issue 10, 25 April 2005, Pages 3223-3229
2. Mubasher Ahmed Bashir, Wolfgang Radke
“Comparison of retention models for polymers: 1. Polyethyleneglycols”
Journal of Chromatography A, Volume 1131, October 2006, Pages 130-141
3. Mubasher Ahmed Bashir, Wolfgang Radke,
“Predicting the chromatographic retention of polymers.
Poly(methyl methacrylate)s and Polyacrylate Blends”
(Submitted to Analytical Chemistry)
Vorträge:
1. “Predicting isocratic and gradient elution of polymers: Comparison of theory
and experiment”
nd February 2005, 2 international symposium on separation and
characterization of natural and synthetic macromolecules, SCM-2,
Amsterdam, Netherlands
2. "Application of theory of polymer chromatography to predict the retention
behaviour of polymers"
June 2006, 20th Bratislava International Conference on Macromolecules,
advanced polymeric materials (APM-2006), Bratislava, Slovakia
Poster:
1. “Gradient elution for the fast estimation of critical composition”
th June 2004, 17 International Symposium on Polymer Analysis and
Characterization (ISPAC-17), Heidelberg, Germany
2. "Virtual chromatography for the fast and effective method development
and optimizations in liquid chromatography of polymers"
June 2006, APM-2006, Bratislava, Slovakia
Contents
1 Introduction ………. 1
1.1 HPLC of polymers ………. 3
1.1.1 Methodology in HPLC of polymers – Basic concepts ………. 3
1.1.1.1 Size exclusion chromatography ………. 4
1.1.1.2 Liquid adsorption chromatography ………. 4
1.1.1.3 Liquid chromatography at critical conditions ………. 6
1.1.1.4 Gradient liquid chromatography ………. 6
1.2 Method development in polymer HPLC ………. 7
1.3 Virtual chromatography ………. 9
1.4 State of the art of virtual chromatography ………. 11
1.5 Objective of this thesis ………. 12
2 Theoretical considerations ………. 14
2.1 Retention models in LC ………. 14
2.1.1 Linear Solvent Strength Model ………. 14
2.1.2 Quadratic Solvent Strength Model ………. 15
2.1.3 Polymer Chromatographic Model ………. 17
2.2 Multi-step or multi-linear gradients and dwell volume ………. 20
2.3 Application of chromatographic models to polydisperse samples ……… 24
2.3.1 Application of LSSM to polydisperse homopolymers ………. 24
2.3.2 Application of QSSM to polydisperse homopolymers ………. 24
2.3.3 Application of PCM to polydisperse homopolymers ………. 25
2.4 Band broadening in liquid chromatography of polymers ………. 26
2.4.1 Band broadening due to sample polydispersity ………. 26
2.4.2 Band broadening due to instrumental setup ………. 28
2.4.2.1 Extra-column band broadening ………. 29 Contents ii

2.4.2.2 Band broadening in column ………. 29
2.5 Prediction of retention behaviour of a polydisperse sample ………. 31
2.5.1 Prediction of peak shapes ………. 31
2.5.1.1 Case of known molar mass and polydispersity ………. 32
2.5.1.2 Case of unknown molar mass and polydispersity ………. 32
3 Results and discussion ………. 34
3.1 Retention behaviour of PEGs ………. 34
3.1.1 Retention behaviour of PEGs in isocratic elution ………. 34
3.1.1.1 Conventional LC models and PEG retention
in isocratic elution ………. 39
3.1.1.2 PCM and retention behaviour of PEG
in isocratic elution ………. 40
3.1.2 Retention behaviour of PEG in gradient elution ………. 44
3.1.2.1 Description of gradient elution of PEG
by the models of LC ………. 46
3.1.2.1.1 Understanding gradient elution of PEG
by conventional LC models ………. 47
3.1.2.1.2 Understanding gradient elution of PEGs
using PCM ………. 49
3.1.3 Prediction of retention behaviour of PEGs ………. 51
3.1.2.1 Isocratic to isocratic prediction ………. 52
3.1.2.2 Gradient to gradient predictions ………. 55
3.1.2.3 Gradient to isocratic predictions ………. 58
3.1.2.4 Isocratic to gradient predictions ………. 61
3.2 Understanding and improving the quality of prediction ………. 64
3.2.1 Identifying the sources of errors ………. 64
3.2.2 Quality of PCM parameters extracted
from gradient calibration ………. 66
Contents iii

3.2.3 Improving the quality of PCM prediction –
influence of initial runs ………. 71
3.2.4 A protocol for the purposeful selection of
calibration experiments ………. 73
3.3 Retention behaviour of poly(methyl methacrylate)s ………. 78
3.3.1 Gradient elution of PMMAs and PCM ………. 78
3.3.2 Prediction of retention behaviour of
poly(methyl methacrylates) ………. 82
3.3.2.1 Gradient to gradient prediction ………. 82
3.3.2.2 Gradient to isocratic prediction ………. 83
3.4 Fast estimation of critical eluent composition for polymers
using gradient experiments ………. 85
3.5 Virtual chromatography for the separation
of homopolymer blend ………. 90
3.6 Retention behavior of statistical copolymers ………. 95
3.6.1 Gradient elution of random SEA copolymers ………. 95
3.6.2 Isocratic elution of random SEA copolymers ………. 97
3.6.3 Predicting the retention behaviour of
random SEA copolymer ………. 99
3.6.3.1 Gradient to gradient prediction ………. 99
3.6.3.2 Gradient to isocratic prediction ………. 100
3.6.3.3 Isocratic retention prediction
from gradient and isocratic experiments ………. 101
3.6.4 Gradient method development for the chemical composition
distribution analysis of SEA copolymers ………. 104
3.7 Prediction of the retention behavior of segmented copolymers - Graft
copolymers of butadiene and methyl methacrylate ………. 108