Solvent Microextraction: Theory and Practice Book

Preface xiii

1 Solvent Microextraction: Comparison With Other Popular Sample Preparation Methods 1

1.1 Introduction 1

1.2 Comparison of Sample Preparation Methods 2

1.2.1 Liquid-Liquid Extraction 3

1.2.2 Liquid-Solid Extraction 5

1.2.3 Headspace Extraction 6

1.2.4 Solid-Phase Microextraction 8

1.2.5 Solvent Microextraction 9

1.3 Summary 13

References 14

2 Basic Modes of Operation for Solvent Microextraction 19

2.1 Basic Principles of SME 19

2.1.1 Introduction 19

2.1.2 Comparison of Classical Solvent Extraction and SME 20

2.2 Extraction Modes 21

2.2.1 Direct-Immersion Modes 22

2.2.2 Headspace Modes 30

2.2.3 Static vs. Dynamic Extraction Modes 31

2.3 Solvents 32

2.3.1 General Rules for Choosing a Solvent 32

2.3.2 Internal and Surrogate Standards 34

References 34

3 Theory Of Solvent Microextraction 37

3.1 Introduction 37

3.2 Thermodynamics 37

3.2.1 Phase Distribution: Fundamental Considerations 37

3.2.2 Solvation and Solvent Selection 40

3.2.3 Octanol-Water Partition Coefficients and Henry's Law Constants 41

3.2.4 Temperature and Salt Effects 41

3.2.5 Solute Equilibria and Speciation: pH and Back-Extraction 42

3.2.6 Dissolution and Evaporation of Solvent 44

3.2.7 Interfacial Adsorption 45

3.3 Kinetics 46

3.3.1 Diffusive Mass Transfer and Fick's Laws 46

3.3.2 Convective-Diffusive Mass Transfer 47

3.3.3 Two-Phase Kinetics 49

3.3.4 Three-Phase Kinetics 56

3.4 Calibration Methods 62

3.5 Summary 63

References 64

4 Practical Considerations For Using Solvent Microextraction 67

4.1 Introduction 67

4.2 General Recommendations 69

4.3 General Questions to Consider Before Performing an Analysis 70

4.3.1What Are the Properties of the Chemicals to Be Extracted? 70

4.3.2 What Type of Sample Matrix Will Be Analyzed? 71

4.3.3 What Analytical Instrumentation Is Available? 71

4.3.4 What Is the Concentration of the Analyte? 71

4.4 Choosing the SME Mode 72

4.4.1 Direct-Immersion Single-Drop Microextraction 72

4.4.2 Headspace Extraction 72

4.4.3 Dynamic Extraction 74

4.4.4 Hollow Fiber-Protected Microextraction 75

4.4.5 Dispersive Liquid-Liquid Microextraction 76

4.5 Extraction Solvent 76

4.6 Sample Volumes 78

4.7 Syringe and Microdrop 79

4.8 Chromatography and Detector Requirements 80

4.9 Additional Extraction Parameters 80

4.9.1 Sample Agitation 80

4.9.2 Ionic Strength 82

4.9.3 Extraction Temperature and Extraction Time 82

4.9.4 Chemical Effects 84

4.10 Calculation Examples for SDME 84

4.11 Calculation Examples for DLLME and HEME 87

4.12 Calculation Examples for the Effect of Ionic Strength on SDME 89

4.13 Calculation Examples for HS-SDME 91

4.14 Calculation Examples for the Effect of Ionic Strength on HS-SDME 93

4.15 Calculation Examples for Static Headspace Extraction 95

4.15.1 Benzene: Static Headspace at Equilibrium 95

4.15.2 Naphthalene: Static Headspace at Equilibrium 95

4.15.3 Pyrene: Static Headspace at Equilibrium 96

4.16 Calculation Examples for Solvent Solubility 97

References 98

5 Method Development In Solvent Microextraction 101

5.1 Introduction 101

5.2 Extraction Mode Selection 102

5.3 Static vs. Dynamic Extraction 107

5.4 Selection of Manual vs. Automated Extraction 108

5.5 Selection of Direct vs. Derivatization SME 109

5.5.1 Preextraction Derivatization 110

5.5.2 Concurrent Extraction-Derivatization 111

5.5.3 Postextraction Derivatization 111

5.6 Extraction Solvent Selection 113

5.7 Selection of Final Determination Method 121

5.8 Selection of Extraction Optimization Method 127

5.9 Optimization of Extraction Conditions 129

5.9.1 Optimization of Sample Volume 129

5.9.2 Optimization of Headspace Volume 134

5.9.3 Optimization of Solvent Volume 137

5.9.4 Optimization of Sample Flow Rate 142

5.9.5 Optimization of Extraction Time 142

5.9.6 Optimization of Sample and Solvent Temperature 144

5.9.7 Optimization of pH of Sample and Acceptor Solution 145

5.9.8 Optimization of Ionic Strength 146

5.9.9 Optimization of Agitation Method and Rate 147

5.9.10 Selection of Fiber Type and Length 148

5.9.11 Optimization of Dynamic Mode Parameters 149

5.9.12 Analytical Characteristics of SME Procedures and Quantitative Analysis 150

References 155

6 Applications 169

6.1 Introduction 169

6.2 Gaseous Samples 171

6.3 Liquid Samples 174

6.4 Solid Samples 176

6.5 Environmental Applications of SME 178

6.5.1 Volatile Hydrocarbons 179

6.5.2 Volatile Halocarbons 183

6.5.3 Volatile Polar Solvents 185

6.5.4 Nonpolar Semivolatile Compounds 189

6.5.5 Polar Semivolatile Compounds 392

6.5.6 Metal Ions, Metalloid Ions, and Organometallic Compounds 196

6.5.7 Other Inorganic Analytes 198

6.5.8 Pesticides 198

6.6 Clinical' and Forensic Applications of SME 204

6.7 Application of SME in Food and Beverage Analysis 211

6.8 Application of SME in the Analysis of Plant Material 215

6.9 Application of SME in the Analysis of Consumer Products and Pharmaceuticals 216

6.10 Outlook for Future Analytical Applications of SME 220

6.11 Physicochemical Applications of SME 223

6.11.1 Study of Drug-Protein Binding 224

6.11.2 Study of Kinetics of the Partitioning Process 226

6.11.3 Study of Mechanistic Aspects of In-Drop Derivatization 226

6.11.4 Pharmacokinetic Studies Using SME 228

6.11.5 Determination of Octanol-Water Partition Coefficients by SME 229

References 230

7 SME Experiments 259

7.1 Introduction 259

7.2 Recommended Experimental Conditions 261

7.3 Determination of Gasoline Diluents in Motor Oil by HS-SDME 264

7.3.1 Experimental 266

7.3.2 Results and Discussion 266

7.3.3 Additional Experimental Recommendations 267

7.4 Determination of BTEX in Water by HS-SDME 267

7.4.1 Experimental 267

7.4.2 Results and Discussion 268

7.4.3 Additional Experimental Recommendations 268

7.5 Analysis of Halogenated Disinfection By-Products by SDME and HS-SDME 269

7.5.1 Experimental: HS-SDME 269

7.5.2 Experimental: SDME 270

7.5.3 Results and Discussion 270

7.5.4 Additional Experimental Recommendations 271

7.6 Analysis of Volatile Organic Compounds by SDME and HS-SDME 271

7.6.1 Experimental: HS-SDME 272

7.6.2 Results and Discussion 272

7.6.3 Experimental: SDME 276

7.6.4 Additional Experimental Recommendations 276

7.7 Analysis of Residual Solvents in Drug Products by HS-SDME 276

7.7.1 Experimental: Manual HS-SDME 277

7.7.2 Results and Conclusions 277

7.7.3 Experimental: Automated HS-SME 277

7.7.4 Results and Conclusions 277

7.7.5 Additional Experimental Recommendations 281

7.8 Arson Accelerant Analyses by HS-SDME 281

7.8.1 Experimental 281

7.8.2 Results and Discussion 282

7.8.3 Additional Experimental Recommendations 284

7.9 Analysis of PAHs by SDME 284

7.9.1 Experimental: SDME Extractions of PAHs from Aqueous Samples 284

7.9.2 Results and Conclusions 285

7.9.3 Experimental: HS-SDME Extractions of PAHs from Aqueous Solutions 285

7.9.4 Results and Conclusions 286

7.9.5 Additional Experimental Recommendations 287

7.10 Determination of Acetone in Aqueous Solutions by Derivatization HS-SDME 287

7.10.1 Experimental 288

7.10.2 Results and Conclusions 288

7.10.3 Additional Experimental Recommendations 288

7.11 Determination of Pesticides in Soil by HF(2)ME 288

7.11.1 Experimental 289

7.11.2 Results and Discussion 289

7.11.3 Additional Experimental Recommendations 290

7.12 Determination of PAHs and HOCs by DLLME 291

7.12.1 Experimental: Extraction of PAHs from Water 291

7.12.2 Experimental: Extraction of HOCs from Water 291

7.12.3 Results and Conclusions 292

7.12.4 Additional Experiment Recommendations 292

7.13 Dynamic Headspace and Direct Immersion Extractions (DY-SME) 292

7.13.1 Experimental 293

7.13.2 Results and Discussion 294

7.13.3 Additional Experimental Recommendations 295

References 295

Acronyms And Abbreviations 299

Appendix SME Modes: Classification And Glossary 303

Index 313