TRACE ANALYSIS

By WILLIAM PEREZ

1 Basic Laboratory Skills 1 11 Introduction 1 12 Safety Aspects 1 13 Recording of Practical Results 3 14 Units 3 15 Sample Handling: Liquids 5 16 Sample Handling: Solids 5 17 Preparing Solutions for Quantitative Work 6 18 Presentation of Data: Tables 6 19 Presentation of Data: Graphs 7 110 Calculations: Dilution Factors 9 Further Reading 11 2 Investigative Approach for Sample Preparation 13 21 Introduction 13 22 Quality Assurance 14 References 25 3 Sampling 27 31 Introduction 27 32 Sampling Methods 29 33 Number of Samples 30 34 Sampling Soil and Sediment 31 35 Sampling Water 34 36 Sampling Air 37 References 37 4 Storage of Samples 39 41 Introduction 39 42 Methods 40 References 45 SAMPLE PREPARATION FOR INORGANIC ANALYSIS 47 5 Solids 49 51 Introduction 50 52 Decomposition Techniques 50 53 Dry Ashing 50 54 Acid Digestion (including the Use of Microwaves) 51 541 Microwave Digestion 55 542 Microwave Digestion Procedure 61 543 Fusion 64 55 Speciation Studies 65 56 Selected Examples of Metal Speciation 66 561 Mercury 66 562 Tin 69 563 Arsenic 70 564 Chromium 75 57 Selective Extraction Methods 76 571 Plant Uptake Studies 76 572 Soil Pollution Studies 76 573 Single Extraction Procedures 78 574 Sequential Extraction Procedure 83 575 Food Studies 88 58 Case Studies on Total and Selective Methods of Metal Analysis 92 581 Example 51: Total Metal Analysis of Soil, followed by Flame Atomic Absorption Spectroscopy 92 582 Example 52: Total Metal Analysis of Soil Using X-Ray Fluorescence Spectroscopy – Comparison with Acid Digestion (Method 3050B), followed by Flame Atomic Absorption Spectroscopy 93 583 Example 53: Sequential Metal Analysis of Soils, followed by Flame Atomic Absorption Spectroscopy 94 References 96 6 Liquids – Natural and Waste Waters 99 61 Introduction 99 62 Liquid–Liquid Extraction 100 63 Ion-Exchange 103 64 Co-Precipitation 104 References 105 SAMPLE PREPARATION FOR ORGANIC ANALYSIS 107 7 Solids 109 71 Introduction 109 72 Soxhlet Extraction 110 721 Example 71: Soxhlet Extraction of Polycyclic Aromatic Hydrocarbons from Contaminated Soil 113 73 Shake-Flask Extraction 114 731 Example 72: Shake-Flask Extraction of Phenols from Contaminated Soil 115 74 Ultrasonic Extraction 116 75 Supercritical Fluid Extraction 118 751 Instrumentation 120 752 Example 73: Supercritical Fluid Extraction of Organochlorine Pesticides from Contaminated Soil and ‘Celite’ 122 76 Microwave-Assisted Extraction 124 761 Instrumentation 124 762 Example 74: Atmospheric Microwave-Assisted Extraction of Polycyclic Aromatic Hydrocarbons from Contaminated Soil 126 763 Example 75: Pressurized Microwave-Assisted Extraction of Polycyclic Aromatic Hydrocarbons from Contaminated Soil 128 77 Pressurized Fluid Extraction 129 771 Instrumentation 130 772 Example 76: Pressurized Fluid Extraction of DDT, DDD and DDE from Contaminated Soil 133 78 Matrix Solid-Phase Dispersion 135 781 Example 77: Matrix Solid-Phase Dispersion of an Alcohol Ethoxylate (Lutensol, C13 and C15, with an Average Ethoxy Chain of EO7), Spiked onto an Homogenized Fish Tissue 135 References 139 8 Liquids 141 81 Liquid–Liquid Extraction 141 82 Solvent Extraction 142 821 Example 81: Liquid–Liquid Extraction of various Polycyclic Aromatic Hydrocarbons from Water 145 83 Solid-Phase Extraction 147 831 Types of SPE Media 148 832 Cartridge or Disc Format 149 833 Method of SPE Operation 152 834 Solvent Selection 154 835 Factors Affecting SPE 155 836 Example 82: Solid-Phase Extraction of various Phenols from Water 156 84 Solid-Phase Microextraction 158 841 Experimental 159 842 Example 83: Solid-Phase Microextraction of BTEX from Water 160 References 164 9 Volatile Compounds 165 91 Introduction 165 92 Thermal Desorption 165 93 Purge-and-Trap 168 931 Example 91: Purge-and-Trap Extraction of BTEX from Water 169 References 172 10 Pre-Concentration Using Solvent Evaporation 173 101 Introduction 173 102 Rotary Evaporation 174 103 Kuderna–Danish Evaporative Concentration 175 104 Automated Evaporative Concentration System 176 105 Gas ‘Blow-Down’ 176 References 182 11 Instrumental Techniques for Trace Analysis 183 111 Introduction 184 112 Environmental Organic Analysis 185 1121 Chromatographic Techniques 185 1122 Other Techniques 191 113 Environmental Inorganic Analysis 192 1131 Atomic Absorption Spectroscopy 192 1132 Atomic Emission Spectroscopy 198 1133 Inductively Coupled Plasma–Mass Spectrometry 201 1134 Other Techniques 203 12 Recording of Information in the Laboratory and Selected Resources 207 121 Recording of Information 207 1211 Introduction 207 1212 Examples of Data Sheets 209 122 Selected Resources 219 1221 Journals 219 1222 Books 219 1223 Software 225 1224 CD-ROMs 226 1225 Videos 226 1226 Useful Websites 226