Abstract from the International Technical Working Group on Fire and Explosives
(October 16, 2002; Orlando, Florida)
John P. Jasper1a, John S. Edwards1b, Larry C. Ford1b, Robert A. Corry2, Francois Fourel3, and Andrew Eaton3.
1Arson Stable Isotope Analysis1 (ASIA). (1aMolecular Isotope Technologies, LLC, 8 Old Oak Lane, Niantic, CT 06357 USA and 1b EFT Analytical Chemists, Inc., 2092 Erkin Smith Road, Nashville, NC 27856 USA.)
2Fire and Explosion Investigation Unit (Ret.), Massachusetts State Fire Office, Mass. State Police, MA USA, and
3Micromass UK Limited, Floats Road, Wythenshawe, Manchester M23 9LZ UK
Stable isotopes are naturally-occurring and ubiquitous, non-radioactive tracers that are being used in studies of forensics and product security. They are typically analyzed in either (i) bulk materials (Bulk Stable Isotope Analysis, or BSIA), (ii) individual compounds (Compound-Specific Isotope Analysis, or CSIA), or (iii) or fragments of individual compounds (Position-Specific Isotope Analysis). The combined specificities of individual analyses can range into the 1-in-millions to the 1-in-billions scale, with the precise specificity difficult to define because of the heterogeneity in natural isotopic distribution. We will present a preliminary study of arson-isotopic analysis as well as a better-refined overview of pharmaceutical Isotopic Product Integrity.
Compound-specific isotope analysis (CSIA) was developed to trace the provenance of individual hydrocarbons in natural petroleum samples. Arson-related accelerants are largely composed of low-to-mid-range hydrocarbons. We suggest that CSIA can be performed on accelerant samples from suspected arson-crime scene sites and from the personal belongings of putative arsonists and/or accelerant containers permitting an evidentiary connection to be made between the suspect and the crime scene.
We have performed isotope analyses under three conditions of evaporation-combustion: (i) Control accelerant: 0% evaporation 87 octane, (ii) Moderately-evaporated gasoline in fire debris. Petroleum-ether wash (ASTM E 1386) of 20 ml of 50%-evaporated gasoline extracted from burned carpet and padding, and (iii) Severely-evaporated accelerant in fire debris. Dynamic headspace separation (ASTM E 1413) and concentration of 10 µl of 90%-evaporated gasoline extracted from burned carpet and padding. Our initial results for the 50%-evaporation experiment show relative small (~0.5‰) and generally consistent 13C-enrichment in the residual gasoline compounds, while the 90%-evaporation results generally span from ~0.3‰ depletion to ~1.3‰ enrichment. Well-controlled evaporation-fractionation experiments on individual organic compounds encourage further research into the behavior of complex accelerant mixtures under varying degrees of evaporation and burn conditions.
For perspective, counterfeiting of pharmaceuticals threatens consumer confidence and product efficacy, as well as the economic well-being of pharmaceutical companies. Our recent studies of the natural stable-isotopic "fingerprints" of pharmaceuticals by BSIA methods indicates a new and highly-specific method for product monitoring that will allow product identification and suppress counterfeiting.
Based on present and earlier analyses, we suggest that stable-isotopic analyses of drug substances and drug products can be used to identify individual batches of these pharmaceutical materials. Such identification permits manufacturers to minimize counterfeiting, countertrading, vicarious liability, and theft. It is generally accepted that it would be much more costly to counterfeit the specific isotopic compositions of given batches of specific pharmaceutical materials than it would be to purchase them legally.
Analytical results presented here of four over-the-counter analgesic drugs and four drug substances (or, Active Pharmaceutical Ingredients = APIs) show that individual batches of each material can be identified on the basis on their bulk isotopic fingerprints. The ability to isotopically trace pharmaceuticals by the batch represents a significant advance in the area of pharmaceutical forensics. Since stable isotopes exist naturally in pharmaceuticals — and in virtually all other materials -- nothing need be added to existing pharmaceutical lines to generate this batch-specific tracer of pharmaceutical materials. The specificity of the technique is analogous to that of DNA identification.
Stable oxygen- ( 18O), carbon- ( 13C), nitrogen- ( 15N) and hydrogen ( D) isotopic compositions of four commercially-available analgesic drugs and four APIs show that the majority of batches of these analgesic products have their own characteristic stable-isotopic fingerprints. In the analgesic sample suite, overall isotopic ranges and precisions are (i) for 18O: 19.2‰ and 0.13‰ (ii) for 13C: 20.0‰ and 0.1‰, and (iii) for D: 24.3‰ and 2‰. In the suite of APIs, isotopic ranges and precisions are (i) for 18O: 21.7‰ and 0.1‰ (ii) for 13C: 21.3‰ and 0.1‰, (iii) for 15N and 4.7‰ and 0.1‰, and (iii) for D: 49.2‰ and 2‰. These results show the broad range of utility of these isotopes in product security.