Foreword ..................................................... xiii
Preface ........................................................ xv
1. Background .................................................. 1
1.1. Introduction .......................................... 1
1.2. History ............................................... 2
1.3. Utility of SEC ........................................ 3
1.4. Molar Mass Averages and Molar Mass Distribution ....... 7
1.5. Structure of The Book ................................ 15
References ........................................... 16
2. Retention .................................................. 18
2.1. Introduction ......................................... 18
2.2. Solute Retention in LC ............................... 19
2.3. Solute Retention in SEC .............................. 22
2.4. SEC Retention Mechanism .............................. 26
2.5. Theoretical Models of SEC Separation ................. 31
2.5.1. Hard-Sphere Solute Model ..................... 32
2.5.2. Rigid Molecules of Other Shapes .............. 35
2.5.3. Random-Coil Solute Model ..................... 37
2.6. Other Considerations ................................. 40
2.6.1. Factors Influencing SEC Retention ............ 40
2.6.2. Failure to Define an Effective Polymer
Radius ....................................... 41
2.6.3. Hydrodynamic Chromatography Effects in SEC ... 43
2.6.4. Slalom Chromatography Effects in SEC ......... 45
References ................................... 47
3. Band Broadening ............................................ 49
3.1. Introduction ......................................... 49
3.1.1. Basic Column-Dispersion Processes ............ 51
3.1.2. Peak Variance ................................ 53
3.2. LC Plate Theory ...................................... 55
3.2.1. Basic Plate Theory ........................... 55
3.2.2. The van Deemter Equation ..................... 58
3.2.3. Flow-Diffusion Coupling ...................... 60
3.2.4. Reduced Plate Height ......................... 64
3.3. Mechanism of SEC Band Broadening ..................... 65
3.3.1. Experimental Verification .................... 66
3.3.2. Rate Theory .................................. 74
3.3.3. Theoretical Inferences ....................... 78
3.4. Influencing Factors .................................. 80
3.4.1. Column Parameters ............................ 81
3.4.2. Kinetic Factors .............................. 83
3.4.3. Experimental Factors ......................... 84
3.5. Experimental Methods ................................. 86
3.5.1. Plate Number ................................. 86
3.5.2. Column-Dispersion Calibration ................ 89
References ................................................. 90
4. Resolution ................................................. 92
4.1. Introduction ......................................... 92
4.1.1. Chromatographic Resolution ................... 92
4.1.2. Peak-Capacity Concept ........................ 96
4.2. Resolution Concept in SEC of Polymers ................ 97
4.3. Molar Mass Accuracy Criterion ........................ 99
4.4. Applications of Column Performance Criteria ......... 102
4.5. Pore Geometry and Operational Effects ............... 107
4.5.1. Connecting Columns .......................... 107
4.5.2. Separation Capacity of Single Pores ......... 108
4.5.3. Effect of Packing Pore-Size Distribution .... 109
4.5.4. Effect of Operating Parameters .............. 112
References .......................................... 115
5. Equipment ................................................. 116
5.1. Introduction ........................................ 116
5.2. Extra-Column Effects: General ....................... 117
5.3. Mobile-Phase Reservoirs, Inlet Filters, and
Degassers ........................................... 118
5.4. Solvent-Metering Systems (Pumps) .................... 119
5.4.1. General Pump Specifications ................. 120
5.4.2. Reciprocating Pumps ......................... 120
5.5. Sample Injectors and Autosampiers ................... 123
5.6. Miscellaneous Hardware .............................. 127
5.7. Laboratory Safety ................................... 129
References .......................................... 129
6. The Column ................................................ 130
6.1. Introduction ........................................ 130
6.2. Column Packings ..................................... 130
6.2.1. Semirigid Organic Gels ...................... 134
6.2.2. Rigid Inorganic Packings .................... 135
6.3. Column-Packing Methods .............................. 137
6.3.1. Particle Technology ......................... 137
6.3.2. Basis of Column-Packing Techniques .......... 138
6.4. Column Performance .................................. 142
References .......................................... 143
7. Experimental Variables and Techniques ..................... 145
7.1. Introduction ........................................ 145
7.2. Solvent Effects ..................................... 145
7.2.1. Sample Solubility ........................... 145
7.2.2. Other Solvent Effects ....................... 158
7.2.3. Flow-Rate Effects ........................... 159
7.2.4. Temperature Effects ......................... 165
7.3. Substrate Effects ................................... 167
7.4. Sample Effects ...................................... 170
7.4.1. Sample Volume ............................... 170
7.4.2. Sample Weight or Concentration .............. 170
7.5. Laboratory Techniques ............................... 172
7.6. Solvent Selection and Preparation ................... 173
7.6.1. Convenience ................................. 173
7.6.2. Sample Type ................................. 173
7.6.3. Effect on Column Packing .................... 174
7.6.4. Operation ................................... 175
7.6.5. Safety ...................................... 175
7.6.6. Solvent Purification and Modification ....... 175
7.7. Selection and Use of Standard Reference Materials ... 176
7.8. Detector Selection .................................. 177
7.9. Column Selection and Handling ....................... 177
7.9.1. Optimum Single Pore-Size Separations ........ 177
7.9.2. Bimodal Pore-Size Separations: Optimum
Linearity and Range ......................... 179
7.9.3. Other Column Selection Guidelines ........... 180
7.9.4. Column Handling ............................. 181
7.10. Chromatographic Design Considerations ............... 181
7.11. Making the Separation ............................... 184
7.11.1. Dissolving the Sample and Standards ......... 184
7.11.2. Sample Solution Filtration .................. 185
7.11.3. Sample Injection ............................ 186
7.11.4. Baseline Stability .......................... 187
7.11.5. Obtaining and Using a Chromatogram
Baseline .................................... 187
7.12. Troubleshooting ..................................... 189
7.12.1. Excessively High Pressure ................... 189
7.12.2. Column Plugging ............................. 189
7.12.3. Air Bubbles and Leaks ....................... 190
7.12.4. Poor Resolution ............................. 190
7.12.5. Low Solute Recovery ......................... 190
7.12.6. Constancy of Separation ..................... 191
7.12.7. Peak Shape .................................. 191
References .......................................... 191
8. Calibration ............................................... 193
8.1. Introduction ........................................ 193
8.2. Calibration with Narrow-MMD Standards ............... 196
8.2.1. Peak-Position (Calibrant-Relative)
Calibration ................................. 196
8.2.2. Universal Calibration ....................... 200
8.2.3. Mark-Houwink Calibration .................... 202
8.3. Calibration with Broad-MMD Standards ................ 204
8.3.1. Integral-MMD Method ......................... 204
8.3.2. Linear Calibration Methods .................. 207
8.4. Accuracy of Calibration Methods ..................... 211
8.5. Actual Molar Mass Across the SEC Elution Curve ...... 215
8.6. Linear Calibration Ranges ........................... 218
8.7. Recent Developments and Recommendations on
Band-Broadening Correction .......................... 219
8.7.1. Algorithm for BBC in Conventional SEC
Analysis with Only a Concentration-
Sensitive Detector .......................... 220
8.7.2. Algorithm for BBC in Dual-Detector SEC
Using an Online Static Light-Scattering
Detector .................................... 223
8.7.3. Algorithm for BBC in Universal Calibration
Using an Online Viscosity Detector .......... 224
8.7.4. Algorithm for BBC in Triple-Detector SEC
Using Online Static Light Scattering,
Viscosity, and Concentration Detectors ...... 227
References .......................................... 228
9. Physical Detectors ........................................ 230
9.1. Introduction ........................................ 230
9.2. Concentration-Sensitive Detectors ................... 231
9.2.1. Differential Refractometers ................. 231
9.2.2. UV/Visible Detectors ........................ 235
9.2.3. Evaporative-Type Detectors .................. 239
9.3. Static Light-Scattering Detection ................... 241
9.3.1. Multiangle Light Scattering ................. 241
9.3.2. Low-Angle Light Scattering .................. 247
9.3.3. Off-Line, Batch-Mode MALS ................... 247
9.3.4. Depolarized MALS ............................ 250
9.4. Quasielastic Light-Scattering Detection ............. 252
9.4.1. QELS Instrumentation ........................ 256
9.5. Viscometric Detection ............................... 257
9.5.1. Single-Capillary Viscometers ................ 258
9.5.2. Differential Viscometers .................... 259
9.5.3. Intrinsic Viscosity and the Viscometric
Radius ...................................... 260
9.5.4. Viscometry Instrumentation .................. 261
9.6. SEC3 ................................................ 262
References .......................................... 264
10. Chemical Detectors ........................................ 266
10.1. Introduction ........................................ 266
10.2. Mass Spectrometry ................................... 267
10.2.1. Electrospray Ionization Mass Spectrometry ... 267
10.2.2. Matrix-Assisted Laser Desorption/
Ionization Time-of-Flight Mass
Spectrometry ................................ 270
10.2.3. Inductively Coupled Plasma Mass
Spectrometry ................................ 274
10.3. Fourier Transform Infrared Spectroscopy ............. 276
10.3.1. FTIR as a Pseudophysical Detector:
Short-Chain Branching Distribution
of Polyolefins .............................. 276
10.3.2. FTIR as a Chemical Detector ................. 277
10.3.3. Comparison of Online and Continuous
Off-Line SEC/FTIR ........................... 280
10.4. Nuclear Magnetic Resonance Spectroscopy ............. 281
10.5. Other Chemical Detectors ............................ 281
10.5.1. Ultraviolet Detection ....................... 281
10.5.2. Fluorescence ................................ 283
10.5.3. Conductivity ................................ 284
10.5.4. Dynamic Surface Tension Detection ........... 285
10.5.5. Microscale Molecular Mass Sensor ............ 287
10.6. Coupling of Chemical Detectors ...................... 287
References .......................................... 289
11. Polymer Architecture and Dilute Solution Thermodynamics ... 292
11.1. Introduction ........................................ 292
11.2. Long-Chain Branching ................................ 293
11.2.1. Quantitating the Long-Chain Branching
Distribution by SEC/MALS .................... 294
11.2.2. Qualitative and Semiquantitative
Descriptions of the Long-Chain Branching
Distribution by SEC/VISC .................... 297
11.2.3. Average Molar Mass Between Long-Chain
Branches .................................... 299
11.3. Determining the Short-Chain Branching
Distribution ........................................ 301
11.4. Polymer Architecture: Conformation and Topology ..... 302
11.4.1. Determining the Fractal Dimension ........... 302
11.4.2. Dimensionless Radii Ratios .................. 307
11.4.3. Dimensionless Functions ..................... 310
11.4.4. Caveats Regarding Dimensionless
Parameters .................................. 311
11.5. Star Polymers ....................................... 313
11.6. Determining the Persistence Length .................. 314
11.7. Determining the Characteristic Ratio ................ 318
11.8. Local Polydispersity ................................ 320
References .......................................... 320
12. Aqueous SEC ............................................... 322
12.1. Introduction ........................................ 322
12.2. Aqueous SEC Columns ................................. 323
12.3. Non-Size-Exclusion Effects and Mobile-Phase
Additives ........................................... 324
12.4. Select Applications of Aqueous SEC .................. 325
12.4.1. Polysaccharides ............................. 326
12.4.2. Proteins and Peptides ....................... 326
12.4.3. Synthetic Polymers .......................... 328
12.4.4. Polyelectrolytes ............................ 334
12.4.5. Inorganic Compounds ......................... 336
References .......................................... 337
13. Oligomeric SEC ............................................ 339
13.1. Introduction ........................................ 339
13.2. What is an Oligomer? ................................ 340
13.3. Preliminary Considerations .......................... 342
13.3.1. Advantages over Polymeric SEC ............... 342
13.3.2. Difficulties as Compared to Polymeric SEC ... 343
13.4. Oligomeric SEC Columns .............................. 347
13.5. Select Applications of Oligomeric SEC ............... 349
13.5.1. Characterization of Tackifiers, Resins,
and Resin Prepolymers ....................... 349
13.5.2. Characterization of Antioxidant Lubricant
Additives ................................... 351
13.5.3. Characterization and Quantitation of
Plasticizers ................................ 352
13.5.4. Polymer Exemption Data ...................... 354
13.5.5. SEC of Oligosaccharides ..................... 356
13.5.6. Determining the Solution Conformational
Entropy of Oligomers ........................ 357
13.5.7. Determining Molar Masses of Oligomers by
SEC/MALS .................................... 360
13.6. Optimizing Resolution in Oligomeric SEC ............. 364
References .......................................... 366
14. SEC in 2D-LC Separations .................................. 368
14.1. Introduction ........................................ 368
14.2. Principles of 2D Polymer Separations ................ 369
14.2.1. Separation Angle and Percent Sуnentropy ..... 370
14.3. Designing an Experimental 2D-LC Protocol ............ 376
14.4. Eluent Transfer in 2D-LC ............................ 379
14.5. Stop-Flow SEC x LC .................................. 380
14.6. Select Applications of 2D-LC ........................ 383
14.6.1. HPLC ........................................ 383
14.6.2. Liquid Chromatography at the Critical
Condition ................................... 387
14.6.3. Other Methods ............................... 388
14.7. SEC in 3D Separations ............................... 390
References .......................................... 391
15. Special Techniques ........................................ 393
15.1. Introduction ........................................ 393
15.2. Preparative SEC ..................................... 393
15.2.1. Experimentation ............................. 394
15.2.2. Applications ................................ 400
15.3. Recycle SEC ......................................... 405
15.3.1. Theory ...................................... 407
15.3.2. Equipment ................................... 408
15.3.3. Uses of the Recycle Method .................. 409
15.4. High-Speed SEC ...................................... 417
15.5. Inverse SEC ......................................... 425
15.6. Vacancy and Differential SEC ........................ 427
15.7. Size-Exclusion Electrochromatography ................ 430
References .......................................... 431
16. High-Temperature SEC and Rheological Connections .......... 434
16.1. Introduction ........................................ 434
16.2. High-Temperature SEC ................................ 434
16.2.1. HT-SEC Instrumentation ...................... 436
16.3. Complementarity of SEC and Rheology ................. 438
16.3.1. Obtaining the MMD from Rheological
Measurements ................................ 438
16.3.2. Obtaining Rheological Properties from SEC
Measurements ................................ 442
16.3.3. Behavior of Dilute Oligomer Solutions ....... 453
References .......................................... 454
Symbols ....................................................... 457
Abbreviations ................................................. 465
Index ......................................................... 469
|
