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Preface

Over 7 years have passed since the 1st edition of this book was published, and practical application as well as theoretical research on preparative chromatography has since then progressed rapidly. This motivated us to revise the content of the 1st edition.

We decided to rearrange the structure in this 2nd edition. Our intention was to present the aspects of practical equipment design and operation together in a separate chapter, to merge the discussion on stationary phases and the selection of chromatographic systems in one chapter, and to reduce the content concerning chromatographic reactors because of their specific features and the still limited practical relevance. These changes provided room for important new sections on ion exchange, bioseparation, and new process concepts and calculation methods.

What else is new in this revised second edition? First of all, the team did change significantly. Besides the additional editors, there are several new authors from industry and academia. The former crew from Dortmund University went to industries and is now active in other fields of chemical engineering. Their names as well as the names of other authors of the first edition are marked by asterisk in the byline of the corresponding chapters.

We are grateful to Klaus Unger, Jules Dingenen, and Reinhard Ditz that they agreed to join us as senior authors. The most challenging task to tackle is presented in Chapter 4 that has been efficiently handled by Abdelaziz Toumi, Joel Genolet, Andre Kiesewetter, Martin Krahe, Michele Morelli, Olivier Ludemann- Hombourger, Andreas Stein, and Eric Valery. It is in the nature of practical design and plant operation that the experience and interests are sometimes different. Additionally, the limited volume further constrains the content. But we hope to meet most of the practical aspects related to design and operation of chromatographic plants.

In Chapter 3, Matthias Jöhnck and Romas Skudas with the team of Michael Schulte combined the formerly separated topics on stationary phases and chromatographic systems to a unique and completely revised chapter and also extended it to ion exchange. We are especially indebted to Malte Kaspereit for his valuable contributions to Chapters 5 and 7. Sebastian Engell provided in Chapter 7 an overview of the latest research results on advanced process control. We hope that this will motivate practitioners to have a closer look at these promising methods.

Finally, we want to acknowledge the assistance of Fabian Thygs, who produced the new drawings and was patient enough to handle all our revisions.

As in the 1st edition, we have summarized the recently published results. In addition, we have made efforts to address preparative and process chromatographic issues from both the chemist and the process engineer viewpoints in order to improve the mutual understanding and to transfer knowledge between both disciplines.

With this book we want to reach colleagues from industries as well as universities interested in chromatographic separation with preparative purpose. Students and other newcomers looking for detailed information about design and operation of preparative chromatography are hopefully other users. Our message to all of them is that chromatography is nowadays rather well understood and not that difficult and expensive as it is often said and perceived. On the other hand, it is of course not the solution for all separation problems.

We would like to thank all authors for their contributions. We apologize for sometimes getting on their nerves pressing them to meet time limits. Last but not least, we thank our families and friends for their patience and cooperation in bringing out this book.

August 2012

Henner Schmidt-Traub

Michael Schulte

Andreas Seidel-Morgenstern

About the Editors

Henner Schmidt-Traub was Professor of Plant and Process Design at the Department of Biochemical and Chemical Engineering, TU Dortmund University, Germany, until his retirement in 2005. He is still active in the research community and his main areas of research focus on preparative chromatography, downstream processing, integrated processes, and plant design. Prior to his academic appointment, Prof. Schmidt-Traub gained 15 years of industrial experience in plant engineering.

Michael Schulte is Senior Director, Emerging Businesses Energy, at Merck KGaA Performance Materials, Darmstadt, Germany. In his PhD thesis at the University of Münster, Germany, he developed new chiral stationary phases for chromatographic enantioseparations. In 1995 he joined Merck and since then he has been responsible for research and development in the area of preparative chromatography, including the development of new stationary phases, new separation processes, and the implementation of Simulated Moving Bed technology at Merck. In his current position, one of the areas of his research is the use of ionic liquids for separation processes.

Andreas Seidel-Morgenstern is Director at the Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany, and holds the Chair in Chemical Process Engineering at the Otto-von-Guericke-University, Magdeburg, Germany. He received his PhD in 1987 at the Institute of Physical Chemistry of the Academy of Sciences in Berlin. From there he went on to work as postdoctoral fellow at the University of Tennessee, Knoxville, TN. In 1994 he finished his habilitation at the Technical University in Berlin. His research is focused on new reactor concepts, chromatographic reactors, membrane reactors, selective crystallization, adsorption and preparative chromatography, and separation of enantiomers among others.

List of Contributors

Jules Dingenen

Horststraat 51

2370 Arendonk

Belgium

Reinhard Ditz

Merck KGaA

Technology Office Chemicals (TO-I)

Frankfurter Str. 250

64291 Darmstadt

Germany

Sebastian Engell

TU Dortmund

Fakultät Bio- und Chemieingenieurwesen

Lehrstuhl für Systemdynamik und Prozessführung

Emil-Figge-Str. 70

44227 Dortmund

Germany

Joel Genolet

Merck Serono S.A.

Corsier sur Vevey

Zone Industrielle B

1809 Fenil sur Corsier

Switzerland

Matthias Jöhnck

Merck KGaA

R&D Performance & Life Science Chemicals

Frankfurter Str. 250

64291 Darmstadt

Germany

Malte Kaspereit

Friedrich-Alexander-Universität Erlangen-Nürnberg

Lehrstuhl für Thermische Verfahrenstechnik

Egerlandstr. 3

91058 Erlangen

Germany

Andre Kiesewetter

Merck KGaA

PC-SRG-Bioprocess Chromatography

Frankfurter Str. 250

64293 Darmstadt

Germany

Martin Krahe

Bideco AG

Bankstr. 13

8610 Uster

Switzerland

Olivier Ludemann-Hombourger

Polypeptide laboratories France

7 rue de Boulogne

67100 Strasbourg

France

Michele Morelli

Merck-Millipore SAS

39 Route Industrielle de la Hardt – Bldg E

67120 Molsheim

France

Henner Schmidt-Traub

TU Dortmund

Fakultät für Bio- und

Chemieingenieurwesen

Lehrstuhl für Anlagen- und Prozesstechnik

Emil-Figge-Str. 70

44227 Dortmund

Germany

Michael Schulte

Merck KGaA

R&D Performance & Life Science Chemicals

Frankfurter Str. 250

64291 Darmstadt

Germany

Andreas Seidel-Morgenstern

Otto-von-Guericke-Universität

Lehrstuhl für Chemische Verfahrenstechnik

Universitätsplatz 2

and

Max-Planck-Institut für Dynamik komplexer technischer Systeme

Sandtorstraße 1

39106 Magdeburg

Germany

Romas Skudas

Merck KGaA

R&D Performance & Life Science Chemicals

Frankfurter Str. 250

64291 Darmstadt

Germany

Andreas Stein

Merck KGaA

Chromatography Global Applied Technology

Frankfurter Str. 250

64291 Darmstadt

Germany

Abdelaziz Toumi

Merck Serono S.A.

Corsier sur Vevey

Zone Industrielle B

1809 Fenil sur Corsier

Switzerland

Klaus K. Unger

Am alten Berg 40

64342 Seeheim

Germany

Eric Valery

Novasep Process

Boulevard de la Moselle

BP 50

54340 Pompey

France

List of Abbreviations

ACD:	At-column dilution
AIEX:	Anion exchanger
ARX:	Autoregressive exogenous
ATEX:	Explosion proof (French: ATmospheres EXplosibles)
BET:	Brunauer–Emmet–Teller
BJH:	Barrett–Joyner–Halenda
BR:	Chromatographic batch reactor
BV:	Bed volume
CACR:	Continuous annular chromatographic reactor
CD:	Circular dichroism (detectors)
CEC:	Capillary electrochromatography
CFD:	Computational fluid dynamics
cGMP:	Current good manufacturing practice
CIEX:	Cation exchanger
CIP:	Cleaning in place
CLP:	Column liquid chromatography
CLRC:	Closed-loop recycling chromatography
COGS:	Cost of goods sold
CPG:	Controlled pore glass
CSEP®:	Chromatographic separation
CSF:	Circle suspension flow
CSP:	Chiral stationary phase
CTA:	Cellulose triacetate
CTB:	Cellulose tribenzoate
DAC:	Dynamic axial compression
DAD:	Diode array detector
DMF:	Dimethyl formamide
DMSO:	Dimethyl sulfoxide
DTA:	Differential thermal analysis
DVB:	Divinylbenzene
EC:	Elution consumption
ECP:	Elution by characteristic points
EDM:	Equilibrium dispersive model
EMG:	Exponential modified Gauss (function)
FACP:	Frontal analysis by characteristic points
FDM:	Finite difference methods
FFT:	Forward flow test
FT:	Flow through
GC:	Gas chromatography
GMP:	Good manufacturing practice
GRM:	General rate model
HCP:	Health care provider
HETP:	Height of an equivalent theoretical plate
HFCS:	High fructose corn syrup
HIC:	Hydrophobic interaction chromatography
H-NMR:	Hydrogen nuclear magnetic resonance (spectroscopy)
HPLC:	High-performance liquid chromatography
HPW:	Highly purified water
IAST:	Ideal adsorbed solution theory
ICH:	International Guidelines for Harmonization
IEX:	Ion exchange
IMAC:	Immobilized metal affinity chromatography
IR:	Infrared
ISEC:	Inverse size exclusion chromatography
ISEP®:	Ion exchange separation
ISMB:	Improved/intermittent simulated moving bed
LC:	Liquid chromatography
LGE:	Linear gradient elution
LHS:	Liquid-handling station
LOD:	Limit of detection
LOQ:	Limit of quantification
LPLC:	Low-pressure liquid chromatography
LSB:	Large Scale Biotech project
MaB:	Monoclonal antibody
mAbs:	monoclonal antibodies
MD:	Molecular dynamics
MPC:	Model predictive control
MS:	Mass spectroscopy
MW:	Molecular weight
NMPC:	Nonlinear model predictive control
NMR:	Nuclear magnetic resonance (spectroscopy)
NN:	Neural network
NP:	Normal phase
NPLC:	Normal-phase liquid chromatography
NSGA:	Non-dominating sorting generic algorithm
OC:	Orthogonal collocation
OCFE:	Orthogonal collocation on finite elements
ODE:	Ordinary differential equation
PAT:	Process analytical technology
PDE:	Partial differential equation
PDT:	Pressure decay test
PEEK:	Poly(ether ether ketone)
PES:	Poly(ethoxy)siloxane
PLC:	Programmable logic controller
PMP:	Polymethylpentene
PSD:	Particle size distribution
QC:	Quality control
R&D:	Research and Development
RI:	Refractive index
RMPC:	Repetitive model predictive control
RP:	Reversed phase
S/N:	Signal-to-noise ratio
SEC:	Size exclusion chromatography
SEM:	Scanning electron microscopy
SFC:	Supercritical fluid chromatography
SIP:	Sanitization in place
SIP:	Steaming in place
SMB:	Simulated moving bed
SMBR:	Simulated moving bed reactor
SOP:	Standard operation procedure
SQP:	Sequential quadratic programming
SSRC:	Steady-state recycling chromatography
St-DVB:	Styrene-divinylbenzene
TDM:	Transport dispersive model
TEM:	Transmission electron microscopy
TEOS:	Tetraethoxysilane
TFA:	Trifluoroacetic acid
TG/DTA:	Thermogravimetric/differential thermal analysis
THF:	Tetrahydrofuran
TLC:	Thin-layer chromatography
TMB:	True moving bed process
TMBR:	True moving bed reactor
TPX™:	Transparent polymethylpentene
UPLC:	Ultrahigh-performance liquid chromatography
USP:	United States pharmacopoeia
UV:	Ultraviolet
VSP:	Volume-specific productivity
WFI:	Water for injection
WIT:	Water intrusion test

Notation

Symbols

Symbol	Description	Units
ai	Coefficient of the Langmuir isotherm	cm3 g−1
as	Specific surface area	cm2 g−1
A	Area	cm2
Ac	Cross section of the column	cm2
Ai	Coefficient in the Van Deemter equation	cm
As	Surface area of the adsorbent	cm2
ASP	Cross section-specific productivity	g cm−2 s−1
bi	Coefficient of the Langmuir isotherm	cm3 g−1
B	Column permeability	m2
Bi	Coefficient in the Van Deemter equation	cm2 s−1
ci	Concentration in the mobile phase	g cm−3
cp,i	Concentration of the solute inside the particle pores	g cm−3
C	Annual costs	€
Ci	Coefficient in the Van Deemter equation	s
CDL,i	Dimensionless concentration in the liquid phase	—
Cp,DL,i	Dimensionless concentration of the solute inside the particle pores	—
Cspec	Specific costs	€ g−1
dc	Diameter of the column	cm
dp	Average diameter of the particle	cm
dpore	Average diameter of the pores	cm
Dan	Angular dispersion coefficient	cm2 s−1
Dapp,i	Apparent dispersion coefficient	cm2 s−1
Dapp,pore	Apparent dispersion coefficient inside the pores	cm2 s−1
Dax	Axial dispersion coefficient	cm2 s−1
Dm	Molecular diffusion coefficient	cm2 s−1
Dpore,i	Diffusion coefficient inside the pores	cm2 s−1
Dsolid,i	Diffusion coefficient on the particle surface	cm2 s−1
Da	Damkoehler number	—
EC	Eluent consumption	cm3 g−1
F	Prices	€ l−1, € g−1
fi	Fugacity	—
h	Reduced plate height	—
hRf	Retardation factor	—
Δhvap	Heat of vaporization	kJ mol−1
Hi	Henry coefficient	—
Hp	Prediction horizon	—
Hr	Control horizon	—
HETP	Height of an equivalent theoretical plate	cm
kads,i	Adsorption rate constant	cm3 g−1 s−1
kdes,i	Desorption rate constant	cm3 g−1 s−1
keff,i	Effective mass transfer coefficient	cm2 s−1
Keq	Equilibrium constant	Miscellaneous
KEQ	Dimensionless equilibrium coefficient	—
kfilm,i	Boundary or film mass transfer coefficient	cm s−1
	Retention factor	—
	Modified retention factor	—
k0	Pressure drop coefficient	—
kreac	Rate constant	Miscellaneous
LF	Loading factor	—
Lc	Length of the column	cm
	Mass flow	g s−1
mi	Mass	g
mj	Dimensionless mass flow rate in section j	—
ms	Total mass	g
ni	Molar cross section of component i	—
nT	Pore connectivity	—
N	Column efficiency, number of plates	—
Ncol	Number of columns	—
Ncomp	Number of components	—
Np	Number of particles per volume element	—
Δp	Pressure drop	Pa
Pe	Péclet number	—
Pri	Productivity	g cm3 h−1
Ps	Selectivity point	—
Pui	Purity	%
qi	Solid load	g cm−3
qi∗	Total load	g cm−3
	Averaged particle load	g cm−3
qsat,i	Saturation capacity of the stationary phase	g cm−3
QDL,i	Dimensionless concentration in the stationary phase	—
r	Radial coordinate	cm
ri	Reaction rate	Miscellaneous
rp	Particle radius	cm
Rf	Retardation factor	—
Ri	Regulation term	—
Rs	Resolution	—
Re	Reynolds number	—
SBET	Specific surface area	m2 g−1
Sc	Schmidt number	—
Sh	Sherwood number	—
St	Stanton number	—
t	Time	s
t0	Dead time of the column (for total liquid holdup)	s
t0,int	Dead time of the column (for interstitial liquid holdup)	s
tcycle	Cycle time	s
tg	Gradient time	s
tinj	Injection time	s
tlife	Lifetime of adsorbent	h
tplant	Dead time of the plant without column	s
tR,i	Retention time	s
tR,i,net	Net retention time	s
tshift	Switching time of the SMB plant	s
ttotal	Total dead time	s
T	Temperature	K
T	Degree of peak asymmetry	—
u0	Velocity in the empty column	cm s−1
uint	Interstitial velocity in the packed column	cm s−1
um	Effective velocity (total mobile phase)	cm s−1
vsp	Specific pore volume	cm3 g−1
V	Volume	cm3
	Volume flow	cm3 s−1
Vads	Volume of the stationary phase within a column	cm3
Vc	Total volume of a packed column	cm3
Vi	Molar volume	cm3 mol−1
Vint	Interstitial volume	cm3
Vm	Overall fluid volume	cm3
Vpore	Volume of the pore system	cm3
Vsolid	Volume of the solid material	cm3
VSP	Volume-specific productivity	g cm3 s−1
wi	Velocity of propagation	cm s−1
x	Coordinate	cm
xi	State of the plant	—
Xi	Mole fraction	—
X	Conversion	%
Xcat	Fraction of catalyst of the fixed bed	—
Yi	Yield	%
Z	Dimensionless distance	—

Greek Symbols

Symbol	Description	Units
α	Selectivity	—
αexp	Ligand density	µmol m−2
β	Modified dimensionless mass flow rate	—
γ	Obstruction factor for diffusion or external tortuosity	—
Γ	Objective function	—
ε	Void fraction	—
ε0	Solvent strength parameter	—
εp	Porosity of the solid phase	—
εt	Total column porosity	—
η	Dynamic viscosity	mPa s
Θ	Angle of rotation	°
	Total ion exchange capacity	mM
λ	Irregularity in the packing	—
µi	Chemical potential	J mol−1
µt	First absolute moment	—
ν	Kinematic viscosity	cm2 s
νi	Stoichiometric coefficient	—
π	Spreading pressure	Pa
ρ	Density	g cm−3
σt	Standard deviation	—
σi	Steric shielding parameter	—
τ	Dimensionless time	—
ϕ	Bed voidage	—
ϕ	Running variable
ψ	Friction number	—
ψreac	Net adsorption rate	g cm−3 s−1
ωj	Coefficient in the triangle theory	—
ω	Rotation velocity	°s−1

Subscripts

Symbol	Description
1, 2	Component 1/component 2
I, II, III, IV	Section of the SMB or TMB process
acc	Accumulation
ads	Adsorbent
c	Column
cat	Catalyst
conv	Convection
crude	Crude loss
des	Desorbent
diff	Diffusion
disp	Dispersion
DL	Dimensionless
eff	Effective
el	Eluent
exp	Experimental
ext	Extract
feed	Feed
het	Heterogeneous
hom	Homogeneous
i	Component i
in	Inlet
inj	Injection
j	Section j of the TMB or SMB process
l	Liquid
lin	Linear
max	Maximum
min	Minimum
mob	Mobile phase
mt	Mass transfer
opt	Optimal
out	Outlet
p	Particle
pore	Pore
pipe	Pipe within HPLC plant
plant	Plant without column
prod	Product
raf	Raffinate
reac	Reaction
rec	Recycle
sat	Saturation
sec	Section
shock	Shock front
SMB	Simulated moving bed process
solid	Solid adsorbent
spec	Specific
stat	Stationary phase
tank	Tank within HPLC plant
theo	Theoretical
TMB	True moving bed process

Definition of Dimensionless Parameters

Péclet number		Convection to dispersion (column)
Péclet number of the particle		Convection to dispersion (particle)
Péclet number of the plant		Convection to dispersion (plant without column)
Reynolds number		Inertial force to viscous force
Schmidt number		Kinetic viscosity to diffusivity
Sherwood number		Mass diffusivity to molecular diffusivity
Stanton number (modified)		Mass transfer to convection

Chapter 1

Introduction

Henner Schmidt-Traub and Reinhard Ditz

1.1 Development of Chromatography

Adsorptive separations have been in use well before the twentieth century. Tswett (1906, 2010), however, was the first who coined the term “Chromatography” in 1903 for the isolation of chlorophyll constituents. Kuhn and Brockmann, in the course of their research recognized the need for more reproducible and also more selective adsorbents, specially tuned for specific separation problems. This recognized demand for reproducible stationary phases led to the development of first materials standardized for adsorption strength and describes the first attempt toward reproducible separations (Unger et al., 2010).

Liquid Chromatography (LC) was first applied as a purification tool and has thereby been used as a preparative method. It is the only technique that enables to separate and identify both femtomoles of compounds out of complex matrices in life sciences, and also allows the purification and isolation of synthetic industrial products in the ton range. The development of modern LC methodology and the corresponding technologies are based on three main pillars, which have developed over different time scales (Figure 1.1).

In the field of preparative and process chromatography the “restart” after the dormant period between the 1930s and the 1960s was not induced by the parallel emergence of analytical HPLC, but from engineering in search of more effective purification technologies. High selectivity of HPLC in combination with the principle to enhance mass transfer by counter current flow significantly increased the performance of preparative chromatography in terms of productivity, eluent consumption, yield, and concentration. The first process of this kind was the Simulated Moving Bed (SMB) chromatography for large-scale separation in the petrochemical area and in food processing. The development of new processes was accompanied by theoretical modeling and process simulation which are a prerequisite for better understanding of transport phenomena and process optimization.

In the 1980s, highly selective adsorbents were developed for the resolution of racemates into enantiomers. These adsorbents were mainly employed in analytical HPLC (Allenmark, 1992). However, the availability of enantioselective packings in bulk quantities also enabled the production of pure enantiomers by the SMB technology in the multi ton range. Productivities larger than 10 kg of pure product per kilogram of packing per day were achieved in the following years. In the 1990s the SMB concept was adapted and down-sized for the production of pharmaceuticals.

While preparative as well as analytical liquid chromatography were heavily relying on equipment and engineering and on the physical aspects of their tools for advancement in their fields, the domain Bioseparation was built around a different key aspect, namely, selective materials that allowed the processing of biopolymers, for example, recombinant proteins under nondegrading conditions, thus maintaining bioactivity. Much less focus in this area was on process engineering aspects, leading to the interesting phenomenon, that large-scale production concepts for proteins were designed around the mechanical instability of soft gels (Janson and Jönsson, 1905). The separation of proteins and other biopolymers has some distinctly different features compared with the separation of low molecular weight molecules from synthetic routes or from natural sources. Biopolymers have a molecular weight (MW) ranging from several thousand to several million. They are charged and characterized by their isoelectric point. More importantly, they have a dynamic tertiary structure that can undergo conformational changes. These changes can influence or even destroy the bio-activity in case of a protein denaturation. Biopolymers are separated in aqueous buffered eluents under conditions that maintain their bioactivity. Moreover, these large molecules exhibit approximately 100 times lower diffusion coefficients and consequently slower mass transfer than small molecules (Unger et al., 2010). Due to these conditions, processes for biochromatography differ substantially from the separation of low-weight molecules. For instance, process pressure which is in many cases much lower for bio-processes than for HPLC requires a different plant design. Selectivity makes another difference; due to the very different retention times of bio-solutes an effective separation is only possible with solvent gradients.

Taking a peek into the future reveals a technology trend toward the use of continuous process operations and also downstream processing. Costs and production capacities will have to be addressed, asking for more integrated and efficient approaches. Adapting counter current solvent gradient concepts for the isolation of antibodies from complex fermentation broths will probably allow for more cost effective downstream processing of biopharmaceuticals within the next couple of years. A similar path might be useful to consider for dealing with the “glyco”-issue. Knowing that glycosylation plays a significant role in therapeutic drug efficacy, the analytical approaches developed around mixed-mode separation methods might be transferred to the process scale within a short time.

Validation of methods and assays will become a key issue. This fits directly with the Process Analytical Technology (PAT) initiative launched already years ago by the Food and Drug Administration (FDA), calling for a better process understanding. Among other things, this requires a much deeper insight into the underlying interactions using model-based approaches, which should finally allow “predictable” process design and monitoring strategies in the future to enhance process robustness and safety.

1.2 Focus of the Book

The general objective of preparative chromatography is to isolate and purify products independent of the amount of material to be separated. During this process, the products have to be recovered in the exact condition that they were in before undergoing the separation. In contrast to this analytical chromatography, which is beyond the content of this book, focuses on the qualitative and quantitative determination of a compound, that is, the sample can be processed, handled, and modified in any way suitable to generate the required information, including degradation, labeling, or otherwise changing the nature of the compounds.

The book describes and develops access to chromatographic purification concepts through the eyes of both engineers and chemists. This includes on one side the fundamentals of natural science and the design of matter and functionalities and on the other side mathematical modeling, simulation and plant design, as well as joined intersections in characterizing matter, process design, and plant operation. Such a joint view is necessary as the earliest possible interaction and cooperation between chemists and engineers is important to achieve time and cost-effective solutions and develop consistent methods that can be scaled up to a process environment.

With the second edition of this book the focus on fine chemicals and small pharmaceutical molecules is expanded to ion-exchange chromatography and the separation of biopolymers such as proteins. In accordance with the first edition these topics are restricted to those applications that can be modeled and simulated by current methods and procedures.

1.3 Recommendation to Read this Book

For most readers it is not necessary to read all chapters in sequence. For some readers the book may be a reference to answer specific questions depending on actual tasks, for others it may be a guide to acquire new fields of work in research or industrial applications. The different chapters are complementary to each other; therefore, it is recommended to be familiar with basic definitions explained in Chapter 2. The book may not provide answers to all questions. In which case, the reader can obtain further information from the cited literature.

Chapter 2 presents the basic principles of chromatography and defines the most important parameters such as retention, retention factor, selectivity, and resolution. It also explains the main model parameters as well as different kinds of isotherm equations including the IAS theory, and the determination of pressure drop. Other passages are devoted to plate numbers, HETP values as well as their determination based on first and second moments. The experienced reader may pass quickly through this chapter to become familiar with definitions used. For beginners this chapter is recommended in order to learn the general terminology and acquire a basic understanding. A further goal of this chapter is the harmonization of general chromatographic terms between engineers and chemists.

Chapter 3 focuses on stationary phases and the selection of chromatographic systems. The first part explains the structure and specifies the properties of stationary phases such as generic and designed phases, reversed-phase silicas, cross-linked organic polymers, and chiral phases, and gives instructions for their maintenance and regeneration. This part may be used as reference for special questions and will help those looking for an overview of attributes of different stationary phases. The second part deals with the selection of chromatographic systems, that is, the optimal combination of stationary phases and eluent or mobile phases for a given separation task. Criteria for choosing NP-, RP-, and CSP-systems are explained and are completed by practical recommendations. Other topics discussed are the processing of monoclonal antibodies and size exclusion. Finally, practical aspects of the overall optimization of chromatographic systems are discussed.

The selection of chromatographic systems is the most critical for process productivity and thus process economy. On one hand, the selection of the chromatographic system offers the biggest potential for optimization but, on the other hand, it is a potential source of severe errors in developing separation processes.

Chapter 4 focuses on practical aspects concerning equipment and operation of chromatographic plants for the production and purification of fine chemicals and small pharmaceutical molecules as well as proteins and comparable bio-molecules. It starts with the market of chromatographic columns followed by chromatography systems, that is, all equipment required for production. This includes high performance as well as low-pressure batch systems and SFC plants as well as continuous SMB systems, supplemented by remarks on auxiliary equipment. Further topics are standard process control and detailed procedures for different methods of column packing. The section on trouble shooting might be an interesting source for practitioners. Especially for the manufacturing of bio-therapeutics special disposable technologies such as prepacked columns and single-use membrane chromatography are exemplified.

Chapter 5 gives an overview of process concepts available for preparative chromatography. Depending on the operating mode, several features distinguish chromatographic process concepts: batch-wise or continuous feed introduction, operation in single- or multicolumn mode, integration of reaction and separation in one process step, elution under isocratic or gradient conditions, recycling of process streams, withdrawal of two or a multitude of fractions, and SMB processes under variable conditions. It finishes with guidelines for the choice of a process concept.

In Chapter 6, modeling and determination of model parameters are key aspects. “Virtual experiments” by numerical simulations can considerably reduce the time and amount of sample needed for process analysis and optimization. To reach this aim, accurate models and precise model parameters for chromatographic columns are needed. Validated models can be used predictively for optimal plant design. Other possible fields of application for process simulation include process understanding for research purposes as well as training of personnel. This includes the discussion of different models for the column and plant peripherals. Besides modeling, a major part of this chapter is devoted to the consistent determination of the model parameters, especially those for equilibrium isotherms. Methods of different complexity and experimental effort are presented which allow a variation of the desired accuracy, on the one hand, and the time needed on the other hand. Chapter 6 ends with a selection of different examples showing that an appropriate model combined with consistent parameters can simulate experimental data within high accuracy.

After general criteria and parameters for process optimization are defined, Chapter 7 focuses first on single-column processes. Design and scaling procedures for batch as well as recycle processes are described and a step-by-step optimization procedure is exemplified. In case of isocratic and gradient SMB processes, rigorous process simulations combined with short-cut calculations based on the TMB-model are useful tools for process optimization, which is illustrated by different example cases. Further sections discuss the improvements of SMB chromatography by variable operating conditions as given by Varicol, PowerFeed, or ModiCon processes. Finally, the latest scientific results on model-based advanced control of SMB processes are presented which are thought to be of increasing importance for practical applications.

References

Allenmark, S. (1992) Chromatographic Enantioseparation: Methods and Applications, Wiley, New York.

Janson, J. and Jönsson, J.-A. (2010) Protein Purification (ed. J.C. Janson), VCH, Weinheim.

Tswett, M.S. (1905) O novoy kategorii adsorbtsionnykh yavleny i o primenenii ikh k biokkhimicheskomu analizu (On a new category of adsorption phenomena and on its application to biochemical analysis), Trudy Varhavskago Obshchestva Estestvoispytatelei, Otdelenie Biologii (Proceedings of the Warsaw Society of Naturalists [i.e., natural scientists], Biology Section), 14, no. 6, 20–39.

Tswett, M.S. (1906) Physical chemical studies on chlorophyll adsorption. Berichte der Deutschen botanischen Gesellschaft, 24, 316–323 (as translated and excerpted in H.M. Leicester, Source Book in Chemistry 1900–1950, Cambridge, MA: Harvard, 1968).

Unger, K., Ditz, R., Machtejevas, E., and Skudas, R. (2010) Liquid chromatography – its development and key role in life sciences applications. Angew. Chemie, 49, 2300–2312.