Capillary Electrophoresis and Microchip Capillary Electrophoresis

Carlos D. García, PhD, is an Associate Professor of Analytical Chemistry at the University of Texas at San Antonio, USA. His group is currently focused on the development of novel bioanalytical strategies involving microfluidics and nanomaterials.Karin Y. Chumbimuni-Torres, PhD, is a Research Associate at the University of Texas at San Antonio, USA. She is interested in pursuing the development of electrochemical biosensors and their integration to microchip-based platforms.Emanuel Carrilho, PhD, is an Associate Professor at the University of Säo Paulo, Brazil. With more than twenty-five years of experience in separation science, his group is focused on the development of analytical methods and instrumentation for bioanalyses.

• PREFACE xviiACKNOWLEDGMENTS xixCONTRIBUTORS xxi1 Critical Evaluation of the Use of Surfactants in Capillary Electrophoresis 1Jessica L. Felhofer, Karin Y. Chumbimuni-Torres, Maria F. Mora, Gabrielle G. Haby, and Carlos D. Garcý´a1.1 Introduction 11.2 Surfactants for Wall Coatings 41.2.1 Controlling the Electroosmotic Flow 41.2.2 Preventing Adsorption to the Capillary 51.3 Surfactants as Buffer Additives 61.3.1 Micellar Electrokinetic Chromatography 61.3.2 Microemulsion Electrokinetic Chromatography 81.3.3 Nonaqueous Capillary Electrophoresis with Added Surfactants 91.4 Surfactants for Analyte Preconcentration 91.4.1 Sweeping 101.4.2 Transient Trapping 111.4.3 Analyte Focusing by Micelle Collapse 121.4.4 Micelle to Solvent Stacking 121.4.5 Combinations of Preconcentration Methods 121.4.6 Cloud Point Extraction 121.5 Surfactants and Detection in CE 141.5.1 Mass Spectrometry 141.5.2 Electrochemical Detection 151.6 Conclusions 16References 172 Sample Stacking: A Versatile Approach for Analyte Enrichment in CE and Microchip-CE 23Bruno Perlatti, Emanuel Carrilho, and Fernando Armani Aguiar2.1 Introduction 232.2 Isotachophoresis 242.3 Chromatography-Based Sample Stacking 252.4 Methods Based on Electrophoretic Mobility and Velocity Manipulation (Electrophoretic Methods) 262.4.1 Field-Enhanced Sample Stacking (FESS) 272.4.2 Field-Enhanced Sample Injection (FESI) 272.4.3 Large-Volume Sample Stacking (LVSS) 282.4.4 Dynamic pH Junction 282.5 Sample Stacking in Pseudo-Stationary Phases 292.5.1 Field-Enhanced Sample Stacking 292.5.2 Hydrodynamic Injection Techniques 302.5.2.1 Normal Stacking Mode (NSM) 302.5.2.2 Reverse Electrode Polarity Stacking Mode (REPSM) 302.5.2.3 Stacking with Reverse Migrating Micelles (SRMM) 302.5.2.4 Stacking Using Reverse Migrating Micelles and a Water Plug (SRW) 312.5.2.5 High-Conductivity Sample Stacking (HCSS) 312.5.3 Electrokinetic Injection Techniques 322.5.3.1 Field-Enhanced Sample Injection (FESI–MEKC) 322.5.3.2 Field-Enhanced Sample Injection with Reverse Migrating Micelles (FESI–RMM) 322.5.4 Sweeping 322.5.5 Combined Techniques 332.5.5.1 Dynamic pH Junction: Sweeping 332.5.5.2 Selective Exhaustive Injection (SEI) 332.5.6 New Techniques 332.6 Stacking Techniques in Microchips 332.7 Concluding Remarks 36References 373 Sampling and Quantitative Analysis in Capillary Electrophoresis 41Petr Kuba´9n, Andrus Seiman, and Mihkel Kaljurand3.1 Introduction 413.2 Injection Techniques in CE 423.2.1 Hydrodynamic Sample Injection 433.2.1.1 Principle 433.2.1.2 Advantages and Performance 443.2.1.3 Disadvantages 443.2.2 Electrokinetic Sample Injection 443.2.2.1 Principle 443.2.2.2 Advantages and Performance 453.2.2.3 Disadvantages 453.2.3 Bias-Free Electrokinetic Injection 453.2.4 Extraneous Sample Introduction Accompanying Injections in CE 463.2.5 Sample Stacking 483.2.5.1 Principle 483.2.5.2 Advantages and Performance 493.2.5.3 Disadvantages 503.2.6 Alternative Batch Sample Injection Techniques 503.2.6.1 Rotary-Type Injectors for CE 503.2.6.2 Hydrodynamic Sample Splitting as Injection Method for CE 513.2.6.3 Electrokinetic Sample Splitting as Injection Method for CE 523.2.6.4 Dual-Opposite End Injection in CE 523.3 Micromachined/Microchip Injection Devices 533.3.1 Droplet Sampler Based on Digital Microfluidics 533.3.2 Wire Loop Injection 543.4 Automated Flow Sample Injection and Hyphenated Systems 553.4.1 Introduction 553.4.2 Advantages and Performance 563.4.3 Disadvantages 573.5 Computerized Sampling and Data Analysis 573.6 Sampling in Portable CE Instrumentation 583.7 Quantitative Analysis in CE 593.7.1 Introduction 593.7.2 Quantitative Analysis with HD Injection 593.7.3 Quantitative Analysis with EK Injection 603.7.4 Validation of the Developed CE Methods 613.7.5 Computer Data Treatment in Quantitative Analysis 613.8 Conclusions 62References 624 Practical Considerations for the Design and Implementation of High-Voltage Power Supplies for Capillary and Microchip Capillary Electrophoresis 67Lucas Blanes, Wendell Karlos Tomazelli Coltro, Renata Mayumi Saito, Claudimir Lucio do Lago, Claude Roux, and Philip Doble4.1 Introduction 674.1.1 High-Voltage Fundamentals 674.1.2 Electroosmotic Flow Control 684.1.3 Technical Aspects 704.1.4 Construction of Bipolar HVPS from Unipolar HVPS 704.1.5 Safety Considerations 714.1.6 HVPS Commercially Available 714.1.7 Practical Considerations 724.1.8 Alternative Sources of HV 724.1.9 HVPS Controllers for MCE 724.2 High-Voltage Measurement 734.3 Concluding Remarks 74References 745 Artificial Neural Networks in Capillary Electrophoresis 77Josef Havel, Eladia Marýa Pe~na-Mendez, and Alberto Rojas-Hernandez5.1 Introduction 775.2 Optimization in CE: From Single Variable Approach Toward Artificial Neural Networks 775.2.1 Limitations of “Traditional” Single Variable Approach 795.2.2 Multivariate Approach with Experimental Design and Response Surface Modeling 795.2.2.1 Experimental Design 795.2.2.2 Response Surface Modeling 805.3 Artificial Neural Networks in Electromigration Methods 815.3.1 Introduction—Basic Principles of ANN 815.3.2 Optimization Using a Combination of ED and ANN 825.3.2.1 Testing of ED–ANN Algorithm 835.3.2.2 Practical Applications of ED–ANN 835.3.3 Quantitative CE Analysis and Determination from Overlapped Peaks 845.3.3.1 Evaluation of Calibration Plots in CE Using ANN to Increase Precision of Analysis 845.3.3.2 ANN in Quantitative CE Analysis from Overlapped Peaks 865.3.4 ANN in CEC and MEKC 865.3.5 ANN for Peptides Modeling 885.3.6 Classification and Fingerprinting 885.3.7 Other Applications 905.4 Conclusions 90Acknowledgments 91References 916 Improving the Separation in Microchip Electrophoresis by Surface Modification 95M. Teresa Fernandez-Abedul, Isabel Alvarez-Martos, Francisco Javier Garcýa Alonso, and Agustýn Costa-Garcýa6.1 Introduction 956.2 Strategies for Improving Separation 966.2.1 Selection of an Adequate Technique: ME 966.2.2 Microchannel Design 966.2.3 Selection of an Appropriate ME Material 966.2.4 Optimization of the Working Conditions 976.2.5 Surface Modification 976.2.5.1 Surface Micro- and Nanostructuring 986.2.5.2 Employment of Energy Sources 996.2.5.3 Chemical Surface Modification 996.3 Chemical Modifiers 1026.3.1 Surfactants 1046.3.2 Ionic Liquids 1056.3.3 Nanoparticles 1086.3.4 Polymers 1106.4 Conclusions 119Acknowledgments 120References 1207 Capillary Electrophoretic Reactor and Microchip Capillary Electrophoretic Reactor: Dissociation Kinetic Analysis Method for “Complexes” Using Capillary Electrophoretic Separation Process 127Toru Takahashi and Nobuhiko Iki7.1 Introduction 1277.2 Basic Concept of CER 1287.3 Dissociation Kinetic Analysis of Metal Complexes Using a CER 1297.3.1 Determination of the Rate Constants of Dissociation of 1:2 Complexes of Al3þ and Ga3þ with an Azo Dye Ligand 2,20-Dihydroxyazobenzene-5,50-Disulfonate in a CER 1307.4 Expanding the Scope of the CER to Measurements of Fast Dissociation Kinetics with a Half-Life from Seconds to Dozens of Seconds: Dissociation Kinetic Analysis of Metal Complexes Using a Microchip Capillary Electrophoretic Reactor (mCER) 1337.5 Expanding the Scope of the CER to the Measurement of Slow Dissociation Kinetics with a Half-Life of Hours 1357.5.1 Principle of LS-CER 1357.5.2 Application of LS-CER to the Ti(IV)–Catechin Complex 1367.5.3 Application of LS-CER to the Ti(IV)–Tiron Complex 1387.6 Expanding the Scope of CER to Measurement of the Dissociation Kinetics of Biomolecular Complexes 1397.6.1 Dissociation Kinetic Analysis of [SSB–ssDNA] Using CER 1397.7 Conclusions 142References 1428 Capacitively Coupled Contactless Conductivity Detection (C4D) Applied to Capillary Electrophoresis (CE) and Microchip Electrophoresis (MCE) 145Jose Alberto Fracassi da Silva, Claudimir Lucio do Lago, Dosil Pereira de Jesus, and Wendell Karlos Tomazelli Coltro8.1 Introduction 1458.2 Theory of C4D 1458.2.1 Basic Principles of C4D 1458.2.2 Simulation 1468.2.3 Basic Equation for Sensitivity 1478.2.4 Equivalent Circuit of a CE-C4D System 1478.2.5 Practical Guidelines 1488.3 C4D Applied to Capillary Electrophoresis 1488.3.1 Instrumental Aspects in CE 1498.3.2 Coupling C4D with UV–Vis Photometric Detectors in CE 1498.3.3 Fundamental Studies in Capillary Electrophoresis Using C4D 1498.3.4 Fundamental Studies on C4D 1498.3.5 Applications 1508.4 C4D Applied to Microchip Capillary Electrophoresis 1518.4.1 Geometry of the Detection Electrodes 1518.4.1.1 Embedded Electrodes 1518.4.1.2 Attached Electrodes 1538.4.1.3 External Electrodes 1538.4.2 Applications 1548.4.2.1 Bioanalytical Applications 1548.4.2.2 On-Chip Enzymatic Reactions 1558.4.2.3 Food Analysis 1558.4.2.4 Explosives and Chemical Warfare Agents 1558.4.2.5 Other Applications 1568.5 Concluding Remarks 156Acknowledgments 157References 1579 Capillary Electrophoresis with Electrochemical Detection 161Blanaid White9.1 Principles of Electrochemical Detection 1619.1.1 Amperometric Detection 1619.1.2 Potentiometric Detection 1629.1.3 Conductivity Detection 1629.2 Interfacing Amperometric Detection to Capillary Electrophoresis 1639.2.1 Off-Column Detection 1639.2.2 End-Column Detection 1649.2.3 Use of Multiple Detection Electrodes 1659.2.4 Pulsed Amperometric Detection 1669.2.5 Nonaqueous EC Detection 1669.2.6 Electrode Material 1669.2.7 Dual Conductivity and Amperometric Detection 1679.3 Interfacing Electrochemical Detection to Microfluidic Capillary Electrophoresis 1689.3.1 End-Column Detection 1689.3.2 Pulsed Amperometric Detection 1699.3.3 Off-Channel Detection 1699.3.4 Electrode Material 1709.3.5 Portable CE and MCE Systems 1709.3.6 Applications of CE–MCE with AD 1719.3.7 Future Directions for CE–MCE with EC Detection 173References 17310 Overcoming Challenges in Using Microchip Electrophoresis for Extended Monitoring Applications 177Scott D. Noblitt and Charles S. Henry10.1 Introduction 17710.2 Background Electrolyte (BGE) Longevity 17910.3 Achieving Rapid Sequential Injections 18610.4 Robust Quantitation 19210.5 Conclusions 197References 19811 Distinction of Coexisting Protein Conformations by Capillary Electrophoresis 201Hanno Stutz11.1 Introduction 20111.1.1 Theoretical Aspects of in vivo Protein Folding 20211.2 Protein Misfolding and Induction of Unfolding 20311.3 Conformational Pathologies 20411.4 Distinction Between Conformations 20511.5 Relevance of Conformations for Biotechnological Products 20611.6 Conformational Elucidation—An Overview of Alternative Methods to CE 20611.7 HPLC in Conformational Distinction 20711.7.1 Intact Proteins 20711.7.1.1 Reversed-Phase (RP)–HPLC 20711.7.1.2 Size Exclusion (SEC)–HPLC 20811.7.1.3 Ion-Exchange–HPLC 20811.7.2 HPLC with Detectors Sensitive for Conformations and Aggregates 20811.7.3 Peptides as Model Compounds for Hydrophobic Stationary Phases in HPLC 20811.8 Capillary Electrophoresis (CE) in Conformational Separations 20911.8.1 Fundamental Aspects and Survey of Pitfalls 20911.8.2 Electrophoretic Mobility of Proteins 21011.8.3 Peak Profiles and Derivable Thermodynamic Aspects of Protein Re-/Unfolding 21111.8.4 Dipeptides as a Case Study for Isomerization 21311.8.5 Denaturation Factors and Strategies Applied in CE 21411.8.5.1 Separation Electrolyte, Injection Solution, and Sample Storage 21511.8.5.2 Denaturation by Urea, Dithiothreitol, and GdmCl 21511.8.5.3 Effects of pH and Organic Solvents 21611.8.5.4 Temperature 21611.8.5.5 Electrical Field 21811.8.5.6 Detergents 21811.8.5.7 Ligands and Ions—Case Studies on Potential Amyloidogenic b2m 22111.8.6 b-Amyloid Peptides 22211.8.6.1 Prions 22311.9 Comparison Between CE and HPLC 22311.10 Conclusive Discussion and Method Evaluation 22311.10.1 General Aspects 22311.10.2 HPLC 22411.10.3 CE 224References 22512 Capillary Electromigration Techniques for the Analysis of Drugs and Metabolites in Biological Matrices: A Critical Appraisal 229Cristiane Masetto de Gaitani, Anderson Rodrigo Moraes de Oliveira, and Pierina Sueli Bonato12.1 Introduction 22912.2 Strategies to Obtain Reliable Capillary Electromigration Methods for the Bioanalysis of Drugs and Metabolites 23012.2.1 Selectivity and Detectability 23012.2.1.1 Efficiency 23212.2.1.2 Sample Preparation 23312.2.1.3 Detectors 23512.2.2 Repeatability 23612.3 Selected Applications of Capillary Electromigration Techniques in Bioanalysis 23812.3.1 Pharmacokinetics and Metabolism Studies 23812.3.2 Enantioselective Analysis of Drugs and Metabolites 24012.3.3 Biopharmaceuticals or Biotechnology-Derived Pharmaceuticals 24012.3.4 Therapeutic Drug Monitoring 24112.3.5 Clinical and Forensic Toxicology 24212.4 Concluding Remarks 243References 24313 Capillary Electrophoresis and Multicolor Fluorescent DNA Analysis in an Optofluidic Chip 247Chaitanya Dongre, Hugo J.W.M. Hoekstra, and Markus Pollnau13.1 Introduction 24713.2 Optofluidic Integration in an Electrophoretic Microchip 24813.2.1 Sample Fabrication 24813.2.2 Optofluidic Characterization 24813.3 Fluorescence Monitoring of On-Chip DNA Separation 24913.3.1 Experimental Materials and Methods 24913.3.2 Experimental Results and Analysis 25013.4 Toward Ultrasensitive Fluorescence Detection 25313.4.1 Optimization of the Experimental Setup 25313.4.2 All-Numerical Postprocessed Noise Filtering 25313.5 Multicolor Fluorescent DNA Analysis 25513.5.1 Dual-Point, Dual-Wavelength Fluorescence Monitoring 25613.5.2 Modulation-Frequency Encoded Multiwavelength Fluorescence Sensing 25913.5.3 Application to Multiplex Ligation-Dependent Probe Amplification 26013.6 Conclusions and Outlook 263Acknowledgments 264References 26414 Capillary Electrophoresis of Intact Unfractionated Heparin and Related Impurities 267Robert Weinberger14.1 Introduction 26714.2 Capillary Electrophoresis and Heparin 26914.3 Method Development in Capillary Electrophoresis 26914.4 Common Impurities Found in Heparin 27214.5 The United States Pharmacoepia and CE of Heparin 27314.6 Interlaboratory Collaborative Study 27414.7 Conclusions 275References 27515 Microchip Capillary Electrophoresis for In Situ Planetary Exploration 277Peter A. Willis and Amanda M. Stockton15.1 Introduction 27715.2 Instrument Design 27915.3 Instrumentation External to the Microdevice 28015.4 Microdevice Basics 28215.4.1 All-Glass Devices for Microchip Capillary Electrophoresis 28215.4.2 Three-Layer Hybrid Substrate Glass–PDMS Devices for Fluidic Manipulation 28415.4.3 Integrating Fluidic Manipulation with Electrophoresis 28515.5 Microdevices and their Applications 28515.5.1 Microdevices with Bus-Valve Control of Microfluidic Manipulation 28515.5.2 Automaton Devices for Programmable Microfluidic Manipulation 28815.6 Conclusions 289Acknowledgments 290References 29016 Rapid Analysis of Charge Heterogeneity of Monoclonal Antibodies by Capillary Zone Electrophoresis and Imaged Capillary Isoelectric Focusing 293Yan He, Jim Mo, Xiaoping He, and Margaret Ruesch16.1 Introduction 29316.2 Capillary Zone Electrophoresis 29516.2.1 Separation and Detection Strategy 29516.2.1.1 Capillary Construction 29516.2.1.2 Buffer Composition 29516.2.1.3 Separation Voltage and Field Strength 29716.2.1.4 Detection 29716.2.2 Applications 29716.3 Imaged Capillary Isoelectric Focusing 29916.3.1 Method Development and Optimization 29916.3.1.1 Carrier Ampholyte 30016.3.1.2 Additives 30016.3.1.3 Focusing Time and Voltage 30016.3.1.4 Salt Concentration 30316.3.1.5 Protein Concentration 30316.3.2 iCE Method Validation 30316.3.3 Applications 30416.3.3.1 Cell Line Development Support 30416.3.3.2 Formulation Screening 30416.3.3.3 Characterization of Acidic Species 30516.4 Summary 306References 30717 Application of Capillary Electrophoresis for High-Throughput Screening of Drug Metabolism 309Roman 9Remý´nek, Jochen Pauwels, Xu Wang, Jos Hoogmartens, Zden9ek Glatz, and Ann Van Schepdael17.1 Introduction 30917.2 Sample Deproteinization 31017.3 On-line Preconcentration 31117.4 Method Development 31217.4.1 Dynamic Coating of Inner Capillary Wall 31217.4.2 Short-End Injection 31317.4.3 Strong Rinsing Procedure 31317.4.4 Optimized Method 31317.5 Method Validation 31417.6 Method Applications 31517.6.1 Drug Stability Screening 31517.6.2 Kinetic Study 31617.7 Conclusions 316Acknowledgments 317References 31718 Electrokinetic Transport of Microparticles in the Microfluidic Enclosure Domain 319Qian Liang, Chun Yang, and Jianmin Miao18.1 Introduction 31918.2 Numerical Model 32018.2.1 Problem Description 32018.2.2 Mathematical Model 32018.3 Numerical Simulation 32218.4 Results and Discussion 32218.4.1 Particle Transport in the Bulk Flow 32218.4.1.1 The Particle Velocity in the Confined Domain 32218.4.1.2 The Trajectory of Particle Transport within the Confined Domain 32318.4.1.3 The Effect of Sidewall Zeta Potential on the Particle Motion 32418.4.2 Particle Transport Near the Bottom Surface 32518.4.2.1 The Effect of the EDLThickness on the Near Wall Motion of the Particle 32518.4.2.2 The Effect of Surface Charge on the Near Wall Transport of the Particle 32518.5 Model Application 32518.6 Conclusions 326References 32619 Integration of Nanomaterials in Capillary and Microchip Electrophoresis as a Flexible Tool 327Germa´n A. Messina, Roberto A. Olsina, and Patricia W. Stege19.1 Introduction 32719.1.1 Historical Overview of Nanotechnology 32719.1.2 Nanomaterials 32919.1.2.1 Carbon-Based Nanomaterials 32919.1.2.2 Metal-Based Nanomaterials 32919.1.2.3 Dendrimers 33119.1.2.4 Composites 33119.2 Nanomaterials in Analytical Chemistry 33219.3 Nanoparticles in Capillary Electrophoresis 33319.3.1 Nanoparticles in Capillary Electrochromatography 33419.3.1.1 Organic Nanoparticles 33419.3.1.2 Inorganic Particles 33819.3.2 Nanoparticles in Electrokinetic Chromatography 34219.3.2.1 Organic Nanoparticles 34319.3.2.2 Inorganic Particles 34719.3.3 Nanoparticles in Microchip Electrochromatography 34919.4 Conclusions 352References 35320 Microchip Capillary Electrophoresis to Study the Binding of Ligands to Teicoplanin Derivatized on Magnetic Beads 359Toni Ann Riveros, Roger Lo, Xiaojun Liu, Marisol Salgado, Hector Carmona, and Frank A. Gomez20.1 Introduction 35920.2 Experimental Section 35920.2.1 Materials and Methods 35920.2.1.1 Equipment and Fabrication of the Microchips 36020.2.1.2 Surface Coating 36020.2.1.3 Teic Immobilization on Magnetic Microbeads 36020.2.2 Procedures 36020.2.2.1 FAMCE Studies 36020.2.2.2 MFAC Studies 36120.3 Results and Discussion 36120.3.1 FAMCE Studies 36120.3.1.1 Nonspecific Adsorption Resistance 36120.3.1.2 The Binding of DA3 to Teic-Beads 36220.3.2 MFAC Studies 36320.4 Conclusions 364Acknowledgments 365References 36521 Glycomic Profiling Through Capillary Electrophoresis and Microchip Capillary Electrophoresis 367Yehia Mechref21.1 Introduction 36721.1.1 Release of N-Glycans from Glycoproteins 36821.1.1.1 Chemical Release 36821.1.1.2 Enzymatic Release 36821.1.2 Release of O-Glycans from Glycoproteins 36821.1.2.1 Chemical Release 36821.1.2.2 Enzymatic Release 36921.2 General Considerations of Capillary Electrophoresis and Microchip Capillary Electrophoresis of Glycans 36921.2.1 Capillary Electrophoresis–Laser-Induced Fluorescence (CE–LIF) Analysis of Glycans 36921.2.2 Interfacing Capillary Electrophoresis and Capillary Electrochromatography to Mass Spectrometry 37221.2.2.1 ESI Interfaces for Capillary Electrophoresis 37221.2.2.2 Sheathless-Flow Interface 37221.2.2.3 Sheath-Flow Interface 37321.2.2.4 Liquid Junction Interface 37321.2.2.5 MALDI Interfaces for Capillary Electrophoresis 37321.2.2.6 CE–MS Analysis of Glycans 37421.2.2.7 Glycomic Analysis by CEC–MS 37621.3 Microchip Capillary Electrophoresis 37721.4 Conclusions 380References 381INDEX 385