Making and Manipulating Capillary Columns f or Gas Chromato-graphy by Kurt Grob

Dr. Alfred Hüthig Verlag Heidelberg Basel New York

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Contents Preface V

1 Introduction 1 1.1 Why Do Some Chromatographers Prefer

to Make Their Own Capillary Columns? . 1 1.2 Glass or Fused Silica? 7 1.3 What Makes a Good Capillary Column? . 11 1.4 Which is the Appropriate Column? . . . 20 1.4.1 Apolar Phases 21 1.4.2 Moderately Polar Phases 24 1.4.3 Polar Phases 29 1.4.4 How to Combine a Stationary Phase

with a Support Surface? 30 1.4.5 Acidic and Basic Columns 32 1.5 How to Organize Individual Column

Preparation? 34 1.6 How to Use This Book? 35

2 General Column Preparation 37 2.1 Materials 37 2.1.1 Varieties of Glass 37 2.1.2 Fused Silica 40 2.1.3 Plastics 41 2.1.4 Glues 44 2.2 Tools 46 2.2.1 Handling of the Raw Material 46 2.2.2 Cutting Tools 50 2.2.3 Burners 52 2.2.4 Tools for Static Coating 57 2.2.5 Tools for Filling Liquids into Capillaries . 60 2.2.6 Sources of Vacuum 64 2.2.7 Tools for Miscellaneous Purposes . . . 67 2.3 Manipulations 73 2.3.1 Producing and Handling the Capillary 73 2.3.2 Cutting 81 2.3.3 Handling Plastics 84 2.3.4 Filling, Rinsing 92 2.3.5 Permanent Connection of Columns . . . 99

Contents

3 Special Column Preparation 105 3.1 Leaching 105 3.1.1 Principles and Processes 105 3.1.1.1 The Purpose 105 3.1.1.2 The Mechanism of Acidic Leaching . . . 105 3.1.1.3 Depth of Leaching 106 3.1.1.4 Efficiency of Deionization 107 3.1.2 Materials and Manipulations 109 3.1.2.1 The Leaching Solution 109 3.1.2.2 Filling the Capillary 109 3.1.2.3 The Leaching Process 110 3.1.2.4 Application to Fused Silica 111 3.1.3 Working Directions 113 3.1.3.1 Working Directions for Glass 113 3.1.3.2 Working Directions for Fused Silica . . . 114

3.2 Rinsing and Dehydration 115 3.2.1 Principles and Processes 115 3.2.1.1 The Purpose 115 3.2.1.2 Rinsing 115 3.2.1.3 Dehydration 117 3.2.2 Materials and Manipulations 119 3.2.2.1 Rinsing 119 3.2.2.2 Dehydration 120 3.2.2.3 Application to Fused Silica 120 3.2.3 Working Directions 122 3.2.3.1 Working Directions for Glass 122 3.2.3.2 Working Directions for Fused Silica . . . 123

3.3 Persilylation 124 3.3.1 Principles and Processes 124 3.3.1.1 The Purpose 124 3.3.1.2 Mechanism of Persilylation 125 3.3.2 Materials and Manipulations 127 3.3.2.1 Selecting a Silylating Agent 127 3.3.2.2 Preparing the Capillary for Silylation . . 130 3.3.2.3 The Reaction; the Ammonia Test . . . . 131 3.3.2.4 Application to Fused Silica 133 3.3.3 Working Directions 134 3.3.3.1 Working Directions for Glass 134 3.3.3.2 Working Directions for Fused Silica . . . 135

3.4 Immobilization 136 3.4.1 Principles and Processes 136 3.4.1.1 TheOrigin 136 3.4.1.2 The Purpose 136 3.4.1.3 Some Principles 138

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3.4.2 Materials and Manipulations 139 3.4.2.1 Selecting the Agent 139 3.4.2.2 Radical-Based Immobilization 141 3.4.2.3 Immobilization of OH-Terminated

Phases 142 3.4.3 Working Directions 144

3.5 Barium Carbonate Treatment 145 3.5.1 Principles and Processes 145 3.5.1.1 TheOrigin 145 3.5.1.2 The Comeback 145 3.5.1.3 The Purpose 146 3.5.1.4 The Mechanism 147 3.5.1.5 Selection of Reagents 149 3.5.2 Materials and Manipulations 150 3.5.2.1 Materials 150 3.5.2.2 The Treatment 151 3.5.2.3 Deactivation 153 3.5.2.4 Application to Fused Silica 153 3.5.3 Working Directions 154

3.6 Static Coating 156 3.6.1 Principles and Processes 156 3.6.1.1 TheOrigin 156 3.6.1.2 The Purpose 156 3.6.1.3 Evaluation 157 3.6.2 Materials and Manipulations 158 3.6.2.1 The Coating Solution 158 3.6.2.2 Concentrations 159 3.6.2.3 Filling the Column 161 3.6.2.4 Closure 163 3.6.2.5 Preventing Breakthrough 164 3.6.2.6 Pumping 167 3.6.2.7 Very Thick Coatings 169 3.6.2.8 Both Ends Uncoated 170 3.6.2.9 Free-Release Static Coating 172 3.6.3 Working Directions 174 3.6.3.1 Working Directions for Glass 174 3.6.3.2 Working Directions for Fused Silica . . . 174

3.7 Dynamic Coating 177 3.7.1 Principles and Processes 177 3.7.1.1 Principles 177 3.7.1.2 Critical Mechanisms 178 3.7.2 Materials and Manipulations 180 3.7.2.1 The Mercury Plug 180 3.7.2.2 TheProcedure 181 3.7.3 Working Directions 184

Contents

3.8 Column Testing 185 3.8.1 Principles and Processes 185 3.8.1.1 The Purpose 185 3.8.1.2 Some Principles 185 3.8.2 Material and Manipulations 186 3.8.2.1 How to Design a General Test? 186 3.8.2.2 The'Grob Test' 187 3.8.3 Working Directions 193

3.9 Immobilized Carbowax Coatings . . . . 194 3.9.1 Principles and Processes 194 3.9.1.1 The Purpose 194 3.9.1.2 Mechanistic Aspects 195 3.9.2 Materials and Manipulations 196 3.9.2.1 Preparing the Glass Surface 196 3.9.2.2 The Coating Solution 197 3.9.2.3 Coating and Immobilization 198 3.9.3 Working Directions 199

References 201

List of Suppliers 203

Appendix 205