Stable Isotope Forensics

Series Foreword xi Foreword: Dame Sue Black xiii Foreword: Mark Harrison xv Foreword to the 1st Edition xvii Book Endorsements xix Preface to the 2nd Edition xxi List of Abbreviations xxv About the CompanionWebsite xxvii Introduction: Stable Isotope 'Profiling' or Chemical 'DNA': A New Dawn for Forensic Chemistry? xxix I How it Works 1 I.1 What are Stable Isotopes? 2 I.2 Natural Abundance Variation of Stable Isotopes 4 I.3 Chemically Identical and Yet Not the Same 12 I.4 Isotope Effects, Mass Discrimination and Isotopic Fractionation 15 I.4.1 Physical Chemistry Background 15 I.4.2 Fractionation Factor and Enrichment Factor 17 I.4.3 Isotopic Fractionation in Rayleigh Processes 19 I.4.3.1 Isotopic Fractionation Summary 20 I.5 Stable Isotopic Distribution and Isotopic Fractionation of Light Elements in Nature 22 I.5.1 Hydrogen 22 I.5.2 Oxygen 26 I.5.3 Carbon 27 I.5.4 Nitrogen 30 I.5.5 Sulfur 32 I.5.6 Isoscapes 35 I.6 Stable Isotope Forensics in Everyday Life 40 I.6.1 "Food Forensics" 42 I.6.1.1 Authenticity and Provenance of Single-Seed Vegetable Oils 42 I.6.1.2 Authenticity and Provenance of Beverages 45 I.6.1.3 Caveats 49 I.6.2 Authenticity and Provenance of other Premium Products 53 I.6.3 Counterfeit Pharmaceuticals 54 I.6.4 Environmental Forensics 59 I.6.5 Wildlife Forensics 61 I.6.6 Anti-Doping Control 62 I.7 Summary of Part I 65 References Part I 67 II Instrumentation, Analytical Techniques and Data Quality 81 II.1 Mass Spectrometry versus Isotope Ratio Mass Spectrometry 82 II.1.1 Stability, Isotopic Linearity and Isotopic Calibration 85 II.2 Instrumentation for Stable Isotope Analysis 90 II.2.1 Dual-Inlet IRMS Systems 92 II.2.2 Continuous-Flow IRMS Systems 93 II.2.3 Bulk Material Stable Isotope Analysis 94 II.2.3.1 13C, 15N and 34S 94 II.2.3.2 2H and 18O 96 II.2.4 Compound-Specific Stable Isotope Analysis of Volatile Organic Compounds 98 II.2.4.1 Compound-Specific 13C or 15N Analysis by GC/C-IRMS 98 II.2.4.2 Compound-Specific 2H or 18O Analysis by GC/HTC-IRMS 100 II.2.4.3 Position-Specific Isotope Analysis 101 II.2.5 Compound-Specific 13C/15N Analysis of Polar, Non-Volatile Organic Compounds by LC-IRMS 101 II.2.6 Compound-Specific Isotope Analysis and Forensic Compound Identification 103 II.3 Quality Control and Quality Assurance in Continuous-Flow Isotope Ratio Mass Spectrometry 106 II.3.1 Compliance with IUPAC Guidelines is a Prerequisite not a Luxury 106 II.3.2 The Identical Treatment Principle 111 II.3.3 The Importance of Scale Normalization 112 II.3.3.1 Scale Normalization of Measured 2H Values to VSMOW 114 II.3.3.2 Scale Normalization of Measured 13C Values to VPDB 120 II.3.3.3 Scale Normalization of Measured 18O Values to VSMOW 122 II.3.3.4 Scale Normalization of Measured 15N Values to Air 126 II.3.3.5 Scale Normalization of Measured 34S Values to VCDT 127 II.4 Points of Note for Stable Isotope Analysis 128 II.4.1 Preparing for Analysis 128 II.4.2 Generic Considerations for BSIA 131 II.4.2.1 Scale Normalization of BSIA 132 II.4.2.2 Keeping Your Powder Dry 134 II.4.2.3 Isobaric Interference 135 II.4.2.4 Ionization Quench Effect 137 II.4.3 Particular Considerations for BSIA 140 II.4.3.1 Bulk 15N Analysis of Nitrates 140 II.4.3.2 Bulk 2H Analysis of Nitrogen-Rich Compounds 141 II.4.3.3 Total 2H versus True 2H Values 141 II.4.3.4 Organic Compounds with Exchangeable Hydrogen and Implications for 2H Abundance Analysis 144 II.4.3.4.1 Chemical and Biochemical Considerations - Example: Hair 152 II.4.3.5 2H Analysis of Human Hair 158 II.4.3.5.1 Two-Point Equilibration with Water at Ambient Temperature 161 II.4.3.5.2 Two-Point End-Member Comparative Equilibration 166 II.4.3.5.3 On-Line Two-Point End-Member Comparative Steam Equilibration 170 II.4.4 Points of Note for CSIA 172 II.4.4.1 Scale Normalization of GC-IRMS Analyses 172 II.4.4.2 Isotope Effects in GC-IRMS during Sample Injection 175 II.4.4.3 The Chromatographic Isotope Effect in GC-IRMS 176 II.4.4.4 Derivatization of Polar Compounds for GC-IRMS 178 II.4.4.5 Compound-Specific 2H Analysis of N- or Cl-Rich Compounds 181 II.5 Statistical Analysis of Stable Isotope Data within a Forensic Context 183 II.5.1 Chemometric Analysis 183 II.5.2 Bayesian Analysis 185 II.6 Quality Control and Quality Assurance in Forensic Stable Isotope Analysis 194 II.6.1 Accreditation to ISO 17025 195 II.6.1.1 Who Assesses the Assessors? 197 II.6.2 The Forensic Isotope Ratio Mass Spectrometry Network 205 II.7 Summary of Part II 207 II.A How to Set Up a Laboratory for Continuous-Flow Isotope Ratio Mass Spectrometry 209 II.A.1 Pre-Installation Requirements 210 II.A.2 Laboratory Location 210 II.A.3 Temperature Control 211 II.A.4 Power Supply 212 II.A.5 Gas Supply 213 II.A.6 Forensic Laboratory Considerations 216 II.A.7 Finishing Touches 217 II.B Sources of International Reference Materials and Tertiary Standards 219 II.C Selected Sample Preparation Protocols 220 II.C.1 Derivatization of Amino Acids for Compound Specific Isotope Analysis by GC-IRMS 220 II.C.2 Acid Digest of Carbonate from Bio-apatite for 13C and 18O Analysis 223 II.C.3 Preparing Silver Phosphate from Bio-apatite for 18O Analysis 225 II.C.4 Two-Point Water Equilibration Protocol for Determination of Non-ex 2H Values of Human Hair 227 II.D Internet Sources of Guidance and Policy Documents 231 III Stable Isotope Forensics: Case Studies and Current Research 247 III.1 Forensic Context 248 III.1.1 Legal Context 249 III.2 Distinguishing Drugs 255 III.2.1 Natural and Semisynthetic Drugs 255 III.2.1.1 Marijuana 255 III.2.1.2 Morphine and Heroin 257 III.2.1.3 Cocaine 259 III.2.2 Synthetic Drugs 263 III.2.2.1 Amphetamines 263 III.2.2.2 Methamphetamine: Synthesis and Isotopic Signature 264 III.2.2.2.1 Two Different Synthetic Routes - Clandestine Conditions 268 III.2.2.3 MDMA: Synthesis and Isotopic Signature 270 III.2.2.3.1 Three Different Synthetic Routes - Controlled Conditions 273 III.2.2.3.2 One Synthetic Route - Variable Conditions 279 III.2.3 "Legal Highs" and "Designer Drugs" 284 III.2.3.1 Mephedrone 284 III.2.3.2 Piperazines 287 III.2.4 Excipients 291 III.2.5 Conclusions 293 III.3 Elucidating Explosives 296 III.3.1 Stable Isotope Analysis of Explosives and Precursors 297 III.3.1.1 Ammonium Nitrate (AN) 298 III.3.1.2 Hexamine, RDX, C4 and Semtex 300 III.3.1.3 Isotopic Product/Precursor Relationship 305 III.3.1.3.1 RDX and HMX 305 III.3.1.3.2 HMTD and TATP 309 III.3.1.4 Hydrogen Peroxide 315 III.3.2 Potential Pitfalls 321 III.3.3 Conclusions 323 III.4 Matching Matchsticks 324 III.4.1 13C-Bulk Isotope Analysis 325 III.4.2 18O-Bulk Isotope Analysis 326 III.4.3 2H-Bulk Isotope Analysis 328 III.4.4 Matching Matches from Fire Scenes 330 III.4.5 Conclusions 331 III.5 Provenancing People 333 III.5.1 Stable Isotope Abundance Variation in Human Tissue 336 III.5.1.1 Hair and Nails 338 III.5.1.1.1 Characteristics of Hair 340 III.5.1.1.2 Characteristics of Nails 342 III.5.1.1.3 Diagenetic Changes of Keratin 342 III.5.1.1.4 2H Isotopic Record in Hair and Nail 343 III.5.1.1.5 18O Isotopic Record in Hair and Nail 345 III.5.1.1.6 13C Isotopic Record in Hair and Nail 346 III.5.1.1.7 15N Isotopic Record in Hair and Nail 347 III.5.1.2 Bone and Teeth 350 III.5.1.2.1 Chemical Composition of Bone and Teeth 351 III.5.1.2.2 Static versus Remodelling Tissue Compartments 352 III.5.1.2.3 Diagenetic Changes of Bone and Teeth Mineral 354 III.5.1.2.4 Diagenetic Changes of Type I Collagen 356 III.5.1.2.5 18O Isotopic Record in Carbonate and Phosphate from Bio-apatite 357 III.5.1.2.6 13C Isotopic Record in Carbonate from Bio-apatite 363 III.5.1.2.7 Isotopic Record in Type I Collagen 364 III.5.1.3 Trophic Level Shift Effect on Stable Isotope Abundance Values in Human Tissue 365 III.5.2 Case Examples 370 III.5.2.1 The Skull from the Sea 371 III.5.2.2 A Human Life Recorded in Hair 375 III.5.2.3 Found in Newfoundland 379 III.5.2.4 The Case of "The Scissor Sisters" 384 III.5.2.5 Too Short a Life 390 III.5.2.6 Saltair Sally 393 III.5.2.7 A Tale of Two Cultures 394 III.5.3 Conclusions and Caveats 397 III.6 Stable Isotope Forensics of Other Physical Evidence 401 III.6.1 Microbial Isotope Forensics 402 III.6.2 Toxins and Poisons 404 III.6.3 Paper, Plastic (Bags) and Parcel Tape 404 III.6.3.1 Paper 404 III.6.3.2 Plastic and Plastic Bags 407 III.6.3.3 Parcel Tape 408 III.6.4 Conclusions 412 III.7 Evaluative Interpretation of Forensic Stable Isotope Data 413 III.7.1 Not Scale Referenced -Values 415 III.7.2 Unresolved Contradictory Data 418 III.7.2.1 Example: "Geographic Provenance of a Murder Victim" 418 III.7.2.2 Example: "Manslaughter due to Negligence" 420 III.7.3 Foregone Conclusions 422 III.7.4 Logical Fallacies 424 III.7.5 Untested Assumptions 426 III.7.6 Conclusion 428 III.8 Summary of Part III 430 III.A An Abridged List of Forensic Stable Isotope Laboratories Worldwide 432 References Part III 434 Recommended Reading 453 Author's Biography 459 Acknowledgements 461 Index 463