2002 Conference Presentations
Some posters and presentations are available to download in pdf format.
Click on the links below to begin download.
Max Coleman
Sean Doyle
Charles Belanger
Prof. Robert M. Kalin
Jim Carter, Emma Titterton, Martin Murray & Richard Sleeman
J. P. Jasper, F. Fourel, A. Eaton, J. Morrison, and A. Phillips
Debra J. Croft, BSc, MSc
F. Fourel
Wolfram Meier-Augenstein
J. Lofthouse, C. Rhodes, K. Heaton, C. Burwood, S. Hird & P. Brereton
Fabien Palhol, Martine Chabrillat, Norbert Naulet
FIRMS network conference 2002
The aim of the conference was to raise awareness of IRMS within the forensic community, inform everybody about the present state of research into this technique and to stimulate further research in the required areas.
FIRMS 2002 Conference Proceedings
The FIRMS 2002 conference proceedings are now available for download as a pdf by clicking the following link:
FIRMS 2002 Conference Proceedings
Conference 2010
Washington DC
The next conference is to be held in Washington DC on the 12, 13 and 14 April 2010 hosted by the FBI.
Details to follow.
FIRMS 2002 - Presentation & Poster Abstracts
Presentation Abstracts
Stable isotope characterisation - how it works, why it works and how good is it.
Max Coleman
Postgraduate Research Institute for Sedimentology, The University of Reading, UK
The aim of this paper is to introduce the topics that will be dealt with in greater detail by the subsequent presentations. Stable isotope determinations are unlike other many other chemical measurements in that the primary methodology produces very precise results but accuracy is not relevant because all values are presented relative to international reference materials. Traditional stable isotope analysis for most light elements involves a chemical preparation stage that produces a gaseous species from the material to be analysed: it is introduced to a Dual inlet mass-spectrometer, alternately with gas produced from a reference material. Although this is the most precise method , Continuous flow mass spectrometry lends itself to on-line sample preparation, smaller sample size, faster analysis and the possibility of interfacing with other separation techniques like Gas-chromatography, but at the cost of poorer precision. Heavier elements are measured by another instrument, a Multi-collector ICP-Mass-spectrometer. Many techniques can be linked to a laser sampling device which gives spatially resolved analysis. In all cases, statistically valid measures of uncertainty must be calculated.
Useful but limited characterisation of materials may be possible if only one isotopic element is measured and depends on the natural range of values and its extension resulting from manufacturing processes. Quality of characterisation improves as the number of isotopic elements analysed for one material is increased. However, isotopic homogeneity or heterogeneity are also valuable characteristics. An essential consideration is the sample integrity and its ability to retain its isotopic compositions. Some materials are susceptible to microbial attack, which may profoundly affect isotope compositions of the partially destroyed residual material. However, even in that case it may be possible to constrain the original values. Most materials are much more refractory and preserve their isotopic characteristics.
In summary stable isotope analysis (like other techniques) is only as good as your care in using it.
Stable isotope ratio profiling (a new kind on evidence).
The challenge and the vision
Sean Doyle
The Forensic Explosives Laboratory, Dstl.
Analytical science currently applied in the support of a justice system can establish a degree of resemblance between one substance and another by means of identifying the constituent elements, cations, anions, functional groups and by elucidating structure.
Should two substances correspond in composition and structure then, with a high degree of certainty, it may be concluded that they are chemically the same substance. Within the sphere of forensic science and crime detection/reduction illicit materials such as drugs and explosives are relevant examples of such substances.
At the very least, measuring the stable isotope composition by mass spectrometry (IRMS) of a particular element would provide a further means of establishing similarity or other wise between one substance and another. In addition, that further means would increase the degree of certainty that may be attached to the opinion that the substances are the same.
It has always been a defence that although the two substances in question are chemically the same they have a different source. For example, the cocaine on the currency or on the hands of a suspect is background contamination and not from the bulk found in possession and, in the field of explosives, the traces on the hand are the result of innocent contamination and did not originate from the bulk in question. This analytical technique may allow the contention to be tested and potentially provides resolution.
Initial research has confirmed the potential probative power of the data provided by this analytical technique. The stable isotope compositions of the elements which are part of a substance are a function of the origin and history of that substance. That is two substances which are chemically the same may have different stable isotope compositions if either their origin or history differ. This could remove the defence of the same substance being from different sources and thus be a significant advance in forensic science, crime detection/reduction and the delivery of justice.
Although falling some way short of the discriminatory power of DNA profiling this technique could significantly increase the probative power of analytical results for fibres, textiles, paints, papers, inks, plastics, adhesives and materials in general, provided the element in question can be converted to the gas state. The chemical elements for which IRMS is useful (e.g. H, C, N, O, S etc) are key components in both natural and manufactured compounds and are frequently major elements (by mass) of the compounds or mixtures for which the forensic scientist wishes to establish a provenance. Thus, IRMS can offer characterisation of the bulk of the material. Furthermore, multi-element IRMS can provide highly diagnostic constraints by defining an unique area of composition when plotted in two dimensions, or an unique volume in multidimensional space.
Research stimulated by the proposed network may establish that the same stable isotope compositions are only found in samples of one and the same substance, ie of the same origin and history. This will effectively be a new means of identification, a significant advance in forensic science, crime detection/reduction and the delivery of justice.
Should the case be demonstrated that the same isotope compositions are conclusive proof of the same origin and history then the need would be obviated for adding taggants for regulatory or crime reduction purposes. Thus, a major economic advantage may accrue.
The presentation will review the current position from a forensic perspective and suggest ways of avoiding past pitfalls and maximising forensic exploitation by means of for example;
· establishing end user requirements
· international collaboration
· burden sharing
· development of international standard protocols
· analytical validation
· forensic validation
Forensics and terrorism: useful stable isotope approaches
Prof. James Ehleringer
Stable Isotope Ratio Facility for Environmental Research, 257 S. 1400 E.,
Department of Biology, University of Utah, Salt Lake City, UT 84112
Stable isotopes may prove useful in several areas related to forensic questions related to domestic and international terrorism. Of particular forensic interest are applications of stable isotopes that either can be used to determine point-of-origin or to determine relatedness of two or more materials of identical chemical composition. In this talk we explore the utility of stable isotopes to several topics: (a) documents and counterfeit currencies, (b) drugs and other controlled substances, (c) tracing human movements, (d) commercial and military explosives, and (d) pathogenic microbes.
Isotopic characterisation of 3,4-methylenedioxymethylamphetamine (ecstasy)
James F Carter (1), Emma L Titterton (2), Martin Murray (1) and Richard Sleeman (2)
(1) School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS
(2) Mass Spec Analytical Ltd, Building 20F, PO Box77, Filton, Bristol, BS99 7AR
Stable isotope characterisation has the potential to "fingerprint" the molecules of a controlled substance, allowing exhibits to be traced to a common source of supply or manufacture and establishing links between trace and bulk materials. The isotopic profile of naturally occurring substances (e.g. cocaine) reflects their biosynthesis. Similarly, the isotopic content of man-made compounds such as 3,4-methylenedioxymethylamphetamine (MDMA) are expected to reflect the materials and methods employed during synthesis. MDMA is typically prepared from a number of cheap and readily available natural products via conversion to 3,4-methylenedioxyphenylacetone and reductive amination to form an N-substituted amine.
The active ingredient was extracted from five batches of seized ecstasy tablet and analysed for d2H, d13C and d15N composition by isotope ratio mass spectrometry. The ten tablets comprising each batch were indistinct from other members of that batch with respect to all the isotopes examined. MDA extracted from one batch of tablets was found to be >2.5 ‰ heavier in 13C than the four batches of MDMA, suggesting a significant contribution from the N-methyl group. Much smaller variations in d13C were observed between the batches of MDMA. In contrast, each batch of tablets had a unique d15N value. Synthetic studies of methamphetamine showed that changes in both d13C and d15N occur during reductive amination. The combined d2H, d13C and d15N data provide a means to discriminate batched of illicit MDMA and MDA.
Four of the batches of ecstasy tablets were found to be isotopically indistinct in d2H whilst one batch of MDMA was approximately 22 ‰ depleted, possibly suggesting a different synthetic origin. 2H NMR analysis of the extracted MDMA revealed that variations in the degrees of deuterium substitution occurred primarily at the methylene and terminal methyl groups, consistent with the known synthesis of MDMA.
Stable isotopic characterization of drug substances and drug products
John P. Jasper (1), Francois Fourel (2), Andrew Eaton (2), John Morrison (2) and Andy Phillips (2)
(1) Molecular Isotope Technologies, LLC, 8 Old Oak Lane, Niantic, CT 06357 USA
Email: JPJasper@MolecularIsotopes.com
(2) Micromass UK Limited, Floats Road, Wythenshawe, Manchester M23 9LZ UK
Counterfeiting of pharmaceuticals threatens consumer confidence and product efficacy, as well as the economic well-being of pharmaceutical companies. Recent studies of the natural stable-isotopic "fingerprints" of pharmaceuticals 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 ("Isotopic Product Authenticity"). 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 drug products or drug substances 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. Stable isotopes are non-radioactive and 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 drug substances or drug products. The specificity of the technique is in one in the millions-to-billions scale, analogous to DNA identification.
Stable oxygen- (d18O), carbon- (d13C), nitrogen- (d15N) and hydrogen (dD) isotopic compositions of four commercially-available analgesic drugs and four APIs strongly indicate 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 d18O: 19.2‰ and 0.13‰ (ii) for d13C: 20.0‰ and 0.1‰, and (iii) for dD: 24.3‰ and 2‰. In the suite of APIs, isotopic ranges and precisions are (i) for d18O: 21.7‰ and 0.1‰ (ii) for d13C: 21.3‰ and 0.1‰, (iii) for d15N and 4.7 and 0.1, and (iii) for dD: 49.2‰ and 2‰.
The use of CF-IRMS as a tool in forensic soil analysis
Debra J. Croft, BSc., MSc.
Forensic Geoscience Unit, Geology Dept.,
Royal Holloway, University of London,
Egham, Surrey, TW20 0EX, UK.
Tel/Fax : 01784 41 41 68
Mobile : 07949 33 27 91
E-mail : d.croft@gl.rhul.ac.uk
Web : www.gl.rhul.ac.uk/SPME/Researchers/Debra
The use of CF-IRMS (continuous flow - isotopic ratio mass spectrometry) as a tool in soil analysis has been assessed as part of a larger study using a variety of geological techniques applied in the forensic context. Carbon and nitrogen abundance, and their isotopic ratios d13C and d15N, have been analysed in soil samples from eight locations. The results are analysed in three contexts: stability over short time periods up to two years, variation over short scale distances, and variation during primary transfer and mixing. The results are presented and the implications for use as expert witness evidence assessed. Over a two-year time-period, variation is largest in the elemental abundance; the isotopic ratios are more robust. Used in combination, the measures can be diagnostic and discriminatory, and are proved for primary transfer.
Forensic applications in continuous flow IRMS using the IsoPrime
Francois Fourel, Andrew Phillips, Ian Abell
Micromass UK Ltd, Floats Road, Wythenshawe, Manchester M23 9LZ
francois.fourel@micromass.co.uk
Since the beginning of stable isotope ratios determinations their potential to be used as tracers has only been growing exponentially to various domains. When most mass spectrometry measurements are used to measure quantities or determine molecular structures, Isotope Ratio Mass Spectrometry (IRMS) is used to determine the origin of the analysed compounds. That can be to differentiate natural/artificial compounds, endogenous, exogenous compounds, metabolic pathways, geographic origins…This unique property has allowed IRMS to be applied first to geochemical studies but then it has become a mandatory tool for fields like environment research, food adulteration and medical research. Although the interest of such a tool is obvious for a field like forensic sciences, some attempts have been made and some significant results have been obtained but it is fair to say that it is not yet common to use IRMS methods to resolve forensic problems.
The purpose of this presentation is to illustrate the power of stable isotopes to be used as tracer of the origin of various products which can be of interest for forensic research.
First we will summarise the basic principle of IRMS methods and describe IRMS instrumentation. Then we will first describe an example of forensic application where stable isotope determinations of 15N by GC-IRMS from various samples of MDMA have been used to evaluate if this could be a valuable method to try to identify the origin of such illicit compounds. Then we will describe a second example where we can demonstrate that stable isotope determinations by EA-IRMS can potentially be used to trace the origin in terms of batch of production from standard drugs like analgesic compounds.
GC/C-IRMS: Potentials and pitfalls
Dr Wolfram Meier-Augenstein
School of Life Sciences, University of Dundee
Coupling capillary gas chromatography (GC) via an on-line sample conversion interface (C) to isotope ratio mass spectrometry (IRMS) has opened the door to highly accurate and precise compound-specific isotope analysis (CSIA) measuring minute variations in isotopic composition of organic compounds at natural abundance level. For this reason, GC/C-IRMS has become the method of choice in archaeology, biological sciences, bio-geochemistry, environmental chemistry and food sciences to obtain information locked into organic molecules not obtainable by other analytical means.
CSIA at natural abundance level provides information on source and origin as well as bio-genetic relation of a given compound. Compared with authentic reference data, subtle differences in the isotopic abundance of 2H, 13C, 15N, 18O or 34S can thus help to uncover adulteration of high quality foods and androgen abuse in sports or to trace origin and source of narcotic drugs or explosives for forensic purposes.
In order to exploit the tremendous potential of CSIA, the user must be aware of the pitfalls usually encountered when analysing complex mixtures of compounds from bio-organic sources. These pitfalls are almost always associated with the various aspects of sample manipulation prior to the isotope abundance measurement rather than the IRMS itself. Unfortunately, the reserve exhibited towards IRMS by some, even today, is often based either on its presumed limitation or the lack of understanding how sensitive IRMS is towards mass discriminatory effects of sample manipulation. This presentation aims to demonstrate the potential of CSIA for areas of applied analytical chemistry such as forensic sciences.
NITE-CRIME Thematic Network:
Natural isotopes and trace elements in criminalistics and environmental forensics
Jurian Hoogewerff (1) and NITECRIME partners (2)
(1) Institute of Food Research, Norwich, UK
(2) too many to put in the heading, see www.nitecrime.eu.com
The NITE-CRIME EU Thematic Network is aimed to assist in the Fight Against Fraud and Crime (EU Framework 5). The enormous material and immaterial damage caused by both fraud and crime implicates that each step towards prevention and/or prosecution can be regarded as both economically and socially beneficial, both on a European and on a global scale. The co-operation in the NITE-CRIME Network between the leading forensic institutions is unique in its kind. The present partners include: IFR-UK, BKA-D, NFI-NL, FBI-US, US Customs, FSS-UK, ETHZ-CH, Curtin Univ.-AU, KTZ-A, IAEA-UN, FIU-US, MNL-ML. The Network disseminates it findings trough publications in peer reviewed journals, contributions to conferences and dedicated workshops.
The requirement to uniquely characterise and compare physical evidence from fraud and environmental casework and crime scenes on an international scale is a major task in forensic science. The main target of the network therefore is to develop, harmonize and validate methods for analysing trace elements and isotopes in forensic materials. New developments in instrumentation like Laser Ablation combined with Quadrupole, Time of Flight, Sector or Multi-Collector ICP-MS (Inductively Coupled Plasma-Mass Spectrometry), have created exciting possibilities for the routine "non-destructive" isotope and trace-element analysis of small and valuable specimens. Although there is an emphasis on laser ablation techniques within the network, for each commodity investigated the optimum trace element or isotope technique is being evaluated. The work program of the network at present includes: float glass, bullets, hair and nails, steel, tape, marble, sugar, bovine serum and MDMA.
Poster Abstracts
The use of Pyrolysis-Isotope Ratio Mass Spectrometry (Py-IRMS) to combat fraud in the food industry: Some lessons to be learnt for applications to forensics.
Janice Lofthouse, Chris Rhodes, Karl Heaton, Chris Burwood, Paul Brereton and Simon Hird.
Central Science Laboratory, Sand Hutton, York, YO41 1LZ.
s.hird@csl.gov.uk
The authenticity of food relates to information on name, ingredients, origin or processing. Examples of fraud include undeclared addition of water or other cheaper materials (adulteration), incorrect declaration of particular ingredients and false statements about sources of ingredients (i.e. geographic, plant or animal origin). Fortunately, stable isotopes have provided a means by which these types of fraud can be detected.
For example, it is possible to detect the adulteration of honey with cane or corn syrup by measuring 13C/12C ratios, because plants using the C4 photosynthetic pathway (e.g. cane and corn) show very different values to those using the C3 pathway. In circumstances where the adulterant uses the same pathway (e.g. beet sugar in apple juice), other isotope ratios, such as 2H/1H and 18O/16O, provide a more powerful discrimination because they reflect other physical and biological processes. For example, 2H/1H ratios obtained by GC-Py-IRMS of sugars, can provide assistance in the detection of beet sugar in fruit juice. Addition of water to wine and fruit juices can be detected using 18O/16O ratios and EA-Py-IRMS shows great potential for the detection of adulteration of olive oil with hazelnut oil.
The application of IRMS to food authenticity issues requires a database of values for authentic samples, to take account of geographical and seasonal effects. This may prove impractical for many forensic applications. An alternative approach is the development of internal isotopic references.
An initial report of the Arson Stable-Isotope Analysis Project
John P. Jasper (1a), John S. Edwards (1b), Larry C. Ford (1b), and Robert A. Corry (2).
Arson Stable Isotope Analysis (1) (ASIA).
(1a) Molecular Isotope Technologies, LLC, 8 Old Oak Lane, Niantic, CT 06357 USA JPJasper@MolecularIsotopes.com
(1b) EFT Analytical Chemists, Inc., 2092 Erkin Smith Road, Nashville, NC 27856 USA.
(2) Detective Lieutenant (Ret.), Commanding Officer, Fire and Explosion Investigation Unit, Massachusetts State Fire Office, Mass. State Police, Mass. USA.
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 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 a causal 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-(50%)-evaporated gasoline in fire debris. Petroleum-ether wash (ASTM E 1386) of 20 ml of 50%-residual gasoline extracted from burned carpet and padding, and (iii) Severely-(90%)-evaporated accelerant in fire debris. Dynamic headspace separation (ASTM E 1413) and concentration of 10 ml-residual gasoline extracted from burned carpet and padding. Our initial results for the 50%-evaporation experiment show relative small (~0.5-1.3o/oo) and generally consistent 13C-enrichment in the residual gasoline compounds, while the 90%-evaporation results generally span from ~0.3o/oo depletion to ~1.3o/oo 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.
Locating the geographic origin of microbial cultures through stable isotope ratio analysis
Helen W. Kreuzer-Martin, Michael J. Lott, and James R. Ehleringer
Stable Isotope Ratio Facility for Environmental Research, 257 S. 1400 E.,
Department of Biology, University of Utah, Salt Lake City, UT 84112
We have tested whether stable isotope ratio analysis might be useful in determining the geographic source of a culture of microbes. We grew Bacillus subtilis, a Gram-positive spore-forming soil bacterium, in media made with waters of varying oxygen and hydrogen stable isotope ratios and harvested both logarithmically growing cells and spores. The hydrogen and oxygen isotope ratio values of both spores and cells were correlated linearly with those of the media water. The slopes and intercepts of the oxygen isotope ratio lines of spores and cells were different, as were the slopes and intercepts of the hydrogen isotope ratio lines of spores and cells. We then used the relationships determined in these experiments to predict the hydrogen and oxygen isotope ratio values of spores grown in nutritionally identical media made with local waters in four different cities in the USA. The results are discussed with the possibility that stable isotope ratio analysis may be a useful tool in determining the geographic origins of microbial cultures.
Locating the origins of explosives through stable isotope ratio analysis
Michael J. Lott, John Howa, and James R. Ehleringer
Stable Isotope Ratio Facility for Environmental Research, 257 S. 1400 E.,
Department of Biology, University of Utah, Salt Lake City, UT 84112
We tested whether stable isotope ratio analysis might be useful in determining the "point of origin" of explosives. Specifically, we examined whether or not differences in production processes or substrates used in the manufacturing process might lead to differences in the isotope ratios of explosives. Distinct stable isotope ratio patterns were observed that allowed us to distinguish between different sources of PETN, RDX, HMX, and AN. The stable isotope ratio patterns of these explosives were also evaluated with respect to batch-to-batch and lot-to-lot variations to better characterize the potential that the stable isotope ratios might represent distinct "fingerprints" that may be of forensic interest.
Detecting the manufacturing origins of pseudoephedrines through stable isotope ratio analysis
Michael J. Lott (1), John Howa (1), James R. Ehleringer (1), J. Fernando Jauregui Q.I. (2),
and Chuck Douthitt (3)
(1) Stable Isotope Ratio Facility for Environmental Research, 257 S. 1400 E., Department of Biology, University of Utah, Salt Lake City, UT 84112
(2) Laboratory of Customs of Mexico, General Administration of Customs, Mexico, Calzada Legaria 608 Mexico D.F., 11500
(3) Finnigan MAT, San Jose, CA
We tested whether stable isotope ratio analysis might be useful in determining the manufacturing source of pseudoephedrines. Specifically, we analyzed suites of samples imported into Mexico and originating from five different countries, to see if there were significant differences in isotopic composition of sufficient magnitude to be used to distinguish "point of origin". The variations that were found in all isotope systems were sufficiently large and distinctive that isotope fingerprinting can indeed be used to unambiguously discriminate between each of the importing countries product. Further work will be required to determine the origin of these differences, whether they arise from differences in source materials or arise during processing.
Stable Isotope Ratio Mass Spectrometry (IRMS) analysis of explosives -
A new type of evidence
A. M. Beardah, D. H. Wakelin, S. A. Phillips & S. P. Doyle
The Forensic Explosives Laboratory, Dstl -Fort Halstead, Sevenoaks, KENT, TN14 7BP.
Energetics Technology Department (ETD)
The Forensic Explosives Laboratory, (FEL), part of the Energetics Technology Department (ETD), provides a forensic service to all UK police forces, UK government departments, foreign governments and other bona fide clients in respect of the criminal misuse of explosives. Current chemical analysis techniques employed within the FEL can confirm the presence of a particular type of explosive, e.g. RDX, with great sensitivity but, are unable to yield information as to whether samples have originated from the same or different sources. However, recent research carried out by FEL has shown that when isotope ratio mass spectrometry is used to measure the ratios of various stable isotopes present within explosive molecules such distinctions can be made. The exact isotope ratios and stable isotope distributions are characteristic of the origin, purity and manufacturing conditions of both explosive end products and their constituents.
Studies to date have been extremely encouraging and have indicated that IRMS analysis can be applied to a wide range of explosive materials including commercial & military high explosives and gunpowder/pyrotechnic compositions. Results have shown that not only do the different types of explosives have significantly different isotope ratios but that the combination of different elemental ratio measurements allows distinctions in the source and purity of samples to be made. Methods for analysis of the carbon (13C/12C), nitrogen (15N/14N), oxygen (18O/16O), sulphur (34S/32S) and chlorine (37Cl/35Cl) isotope ratios of explosive samples have been developed.
Subject to further feasibility studies, it is hoped that IRMS analysis will provide a powerful new form of forensic evidence which will be of great value in the future investigation of terrorism, internal security and other explosives related crime and therefore in the delivery of justice.
The use of GC-C-IRMS analyses for linking seizures of Ecstasy tablets
F. Palhol
Laboratoire des Douanes de Paris, 1 rue G. Vicaire, 75003 Paris, France
Ecstasy (3,4-methylendioxymethamphetamine, MDMA) is becoming a major drug of abuse. Contrary to illicit drugs derived from plant extracts, isotopic measurement can not provide information on geographical origin for synthetic drugs. In this case, isotopic ratios might be expected to depend on precursors and on the synthetic route used. In this study, we have investigated the potential of isotopic analyses to establish links between seizures of MDMA tablets. 13C/12C and 15N/14N isotopic ratios were measured by gas chromatography - combustion - isotope ratio mass spectrometry (GC-C-IRMS) for some ecstasy tablets seized by French Customs in the last three years.
As expected, d13C values vary between -24 and -28 ‰, close to the most common starting materials derived from natural products. More interesting, the last step of the syntheses consists in the addition of an amine function. The wide variety of the origin of the possible nitrogenous precursors and the number of routes used explain the large range of variation observed in d15N for MDMA (-17 to +19 ‰). Results show that d15N is a discriminating factor and can be an aid in linking different seizures.
Influence of synthetic route on isotopic fractionation was also studied for three routes commonly used in clandestine laboratories in Europe. Each route presents a specific fractionation rate, which allows discrimination between different syntheses. Thus, seized materials can be divided in several batches of common origin and d15N value allow us to assume that samples originate from the same laboratory, despite the distance between places of seizures.
