Unified Separation Science

Unifies the complex welter of techniques used for chemical separations by clearly formulating the concepts that are common to them. The mass transport phenomena underlying all separation processes are developed in a simple physical-mathematical form. The limitations and optimum performance of alternative separation techniques and the factors enhancing and limiting separation power can thus be described and explored. Generously illustrated and contains numerous exercises. Long awaited in the scientific community, it breaks new ground in understanding separation processes.

J. Calvin Giddings was a professor of chemistry at the University of Utah. He is credited with the invention of field flow fractionation. On May 27, 1987 Giddings received an honorary doctorate from the Faculty of Pharmacy at Uppsala University, Sweden.

Mathematical Symbols

xv

Abbreviations

xxi

Introduction

1

(15)

Basic Representations of Separations

2

(1)

Analytical and Preparative Separation

3

(4)

Literature of Analytical Separations

7

(1)

Separation Criteria

8

(1)

Concentration Levels

9

(1)

Thermodynamic Limitations

9

(2)

Origin of Separation in Displacement

11

(2)

Methods of Separation

13

(3)

References

14

(1)

Exercises

15

(1)

Equilibrium: Driving Force for Separative Displacement

16

(21)

Mechanical Versus Molecular Equilibrium

16

(1)

Molecular Equilibrium in Closed Systems

17

(2)

Equilibrium in Open Systems

19

(3)

Equilibrium in External Fields

22

(2)

Factors Controlling Equilibrium between Phases

24

(3)

Molecular Interaction and Polarity Scales

27

(4)

Entropy Effects in Phase Distribution: Porous Media

31

(6)

References

35

(1)

Exercises

36

(1)

Separative Transport

37

(18)

Transport: Driven by Equilibrium

37

(1)

Irreversible Thermodynamics

38

(1)

Mechanical Versus Molecular Transport

39

(2)

Molecular Transport

41

(5)

Transport with Flow

46

(1)

Transformation to Concentration Units

46

(2)

Summary of Principal Transport Equations

48

(1)

Physical Interpretation of Transport Equations

48

(1)

Transformation of Coordinates for Zones in Uniform Translation

49

(6)

References

51

(1)

Exercises

52

(3)

Flow Transport and Viscous Phenomena

55

(31)

Mechanics of Flow

56

(1)

Sources of Flow

56

(1)

Viscosity

57

(1)

Flow in Capillaries

58

(4)

Flow in Packed Beds

62

(3)

Compressible Flow: Basis of Gas Chromatography

65

(3)

Capillarity: Flow Origin in Paper and Thin-Layer Chromatography

68

(3)

Convective Flow

71

(2)

Electroosmotic Flow

73

(1)

Laminar and Turbulent Flow

74

(1)

Viscosity: Pivotal Role

75

(1)

Separation Speed, Friction Coefficients, and Viscosity

76

(1)

Friction Coefficients and Molecular Parameters

77

(3)

Viscosity Reduction in Liquids

80

(6)

References

82

(1)

Exercises

83

(3)

Zone Formation and Resolution

86

(26)

Gaussian Zones

86

(4)

Statistical Moments

90

(2)

Random Processes, Variance, and Diffusion

92

(2)

Mechanisms of Zone Broadening

94

(2)

Plate Height: A Zone Spreading Index

96

(3)

Plate Height in Elution Systems

99

(2)

Resolution

101

(4)

Peak Capacity

105

(1)

Non-Gaussian Zones

106

(6)

References

108

(1)

Exercises

109

(3)

Steady-State, Two-Dimensional, and Overlapping Zones

112

(29)

Steady-State Zones

112

(3)

Examples of Steady-State Zones

115

(4)

Zone Formation in Two Dimensions

119

(3)

Two-Dimensional Separations

122

(4)

Resolving Power in Two-Dimensional Separations

126

(2)

Overlapping Zones

128

(3)

Statistics of Peak Overlap

131

(5)

Approaches to Solving the Peak Overlap Problem

136

(5)

References

137

(1)

Exercises

138

(3)

Classification and Comparison of Methods

141

(14)

Problems and Opportunities in Classification

141

(2)

Classification Based on Transport

143

(1)

Categories of Separations

144

(5)

Flow-Assisted Separation

149

(1)

Types of Flow

150

(2)

Flow Parallel to Field or Interface Gradient, F(=)

152

(1)

Flow Perpendicular to Field or Interface Gradient, F(+)

152

(3)

References

153

(1)

Exercises

154

(1)

Separation by External Fields (Sc Methods): Electrophoresis and Sedimentation

155

(34)

Types and Uses of Fields

155

(3)

Transport and Theoretical Plates

158

(1)

Electrophoresis: Capillary, Gel, and Other Forms

159

(6)

Separation Power in Electrophoresis

165

(2)

Electrophoresis: Additional Considerations

167

(3)

Sedimentation

170

(3)

Separation Power in Sedimentation

173

(1)

Thermal Diffusion: Overlooked Opportunity?

174

(2)

Optimization in Static Field (Sc) Systems

176

(1)

Steady-State Variants of Sc Methods: Isoelectric Focusing and Isopycnic Sedimentation

177

(3)

Separation Power of Steady-State Methods

180

(9)

References

184

(2)

Exercises

186

(3)

Separation Using Perpendicular Flow, F(+): Field-Flow Fractionation, Chromatography, and Related Methods

189

(34)

Role of Chemical Potential Profile

189

(1)

Separation Power in F(+) Systems

190

(1)

Zone Migration

191

(2)

Zone Spreading

193

(2)

Optimization

195

(2)

Equilibrium and Nonequilibrium

197

(1)

Overview of F(+)cd Separations

198

(2)

Field-Flow Fractionation

200

(6)

Factors Controlling Retention in FFF

206

(4)

Plate Height and Optimization in FFF

210

(1)

Variants of Field-Flow Fractionation

211

(3)

Overview of F(+)d Separations

214

(2)

Chromatography

216

(7)

References

219

(2)

Exercises

221

(2)

Chromatography: A Deeper Look

223

(27)

Scope of Chromatography

225

(7)

Chromatographic Migration

232

(4)

Migration and Zone Shape in Nonlinear Chromatography

236

(1)

Effect of Gas Compressibility on Retention in GC

237

(3)

Effect of Gradients on Migration in TLC and PC

240

(1)

Nonequilibrium Migration

241

(9)

References

246

(1)

Exercises

247

(3)

Chromatography From a Molecular Viewpoint

250

(19)

Molecular Basis of Migration

250

(3)

Molecular Basis of Zone Spreading

253

(2)

Longitudinal Molecular Diffusion

255

(1)

Stationary Phase Sorption-Desorption

256

(3)

Flow and Diffusion in the Mobile Phase

259

(7)

Overall Plate Height Expression

266

(3)

References

266

(1)

Exercises

267

(2)

Plate Height and Optimization in Chromatography

269

(24)

Plate Height Equations

269

(4)

Plate Height and Gas Compressibility

273

(1)

Reduced Plate Height

274

(4)

Optimization: Higher Resolution

278

(7)

Optimization: Faster Separation

285

(8)

References

289

(1)

Exercises

290

(3)

Appendix I Answers to Exercises

293

(4)

Appendix II Author's Related Publications

297

(10)

Author Index

307

(6)

Subject Index

313

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Unified Separation Science

Summary

Author Biography

Table of Contents

Supplemental Materials