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FIRMS network conference 2005

2005 conference photograph

The aim of this conference was to cover issues relating to the progress of the network since inception towards implementing the FIRMS technical strategy and recent developments in the field of forensic IRMS research and technology.

 

FIRMS 2005 Conference Proceedings

The FIRMS 2005 conference proceedings are now available for download as a pdf by clicking the following link:
FIRMS 2005 Conference Proceedings
delegates at table

Conference 2010

Washington DC

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 2005 - Presentation & Poster Abstracts


Presentation Abstracts

 



The FIRMS Network – from the Early Years to Now – but what of the future?

Max Coleman


University of Reading and NASA Jet Propulsion Laboratory

Sean Doyle


Forensic Explosives Laboratory
 


The network now known as FIRMS was founded just over three years ago by ten members with a grant won from the EPSRC. Its scientific objectives included definition of characteristic ranges of isotope values for relevant manufactured chemicals, their heterogeneity, controls on these compositions, what could change the values, and thus identification of the limitations of this approach. The other aims were to identify analytical barriers to application of the technique, raise awareness of its potential and stimulate research. We now have over 100 members, held one previous general meeting in 2002, established a web-site issued newsletters, produced a technical strategy document and formed three focus groups looking at drugs, explosives and general forensics, respectively. We are happy that we have made a difference and may even be able to convince EPSRC that we have done so in our final report. However, the aim of this paper is to act as an introduction to a discussion session. Our intent for this discussion is to harvest the opinions of those who really count, those who are attending this meeting. We want frank input to help us review the network and its work to date, but equally importantly what do you want for the future?




Analysis of Explosives by isotope ratio mass spectrometry –
an australian perspective


Sarah Benson (a, b), Dr. Chris Lennard (a), Dr. Philip Maynard (b), Dr. Claude Roux (b)

(a) Forensic Services, Australian Federal Police, GPO Box 401, Canberra, ACT, Australia, 2601
(b) Department of Chemistry, Materials and Forensic Science, University of Technology, Sydney, PO Box 123, Broadway, NSW, Australia, 2007



In Forensic Science it is generally not possible to distinguish one source of the same substance from another. As a result, in the case of explosives, if the explosive residues identified at a scene cannot be differentiated from a known source of explosives (e.g. in the possession of a suspect) the strongest conclusion reported is that they are chemically the same substance. However, the question often arises: could they have originated from different sources?


Stable isotope ratio mass spectrometry (IRMS) shows the potential to be able to differentiate between different sources of the same substance.

The Australian Federal Police (AFP) is in the process of developing, optimising and validating methods for the analysis of explosives using IRMS. Once methods are validated, a range of different explosives will be analysed from manufacturers in the region to determine if it is possible to differentiate substances from different manufacturers and different batches. Field experiments will be conducted and post-blast samples analysed by IRMS for comparison with the pre-blast samples. The aim is to create an explosives database incorporating products manufactured in Australia and the South-East Asian region.

An Australian aspect will be presented, highlighting the types of explosives commonly encountered in Australia and the South-East Asian region. Some preliminary IRMS results and the development of a suitable database will be discussed.




Preliminary studies of smokeless powders using molecular and stable isotopic analysis


Ryan Brogden, Lyndon Berwick, Paul Greenwood, Kliti Grice, John Watling


Curtin University of Technology, Australia


Smokeless powders and their residues may be found at crime scenes where a firearm has been discharged or an improvised explosive device (IED) such as a pipe bomb detonated. The unambiguous matching of the original powder or residues found at the scene, with original material and residues found on a possible suspect, will facilitate forensic investigations into provenance establishment of this material and confident prosecution of offenders.

While traditional analytical methods such as SEM-EDX, GCMS, HPLC and more recently CE have been variously applied to the identification of both organic and inorganic constituents of powders, all these techniques still lack definitive specificity and the ability to provide unambiguous data with which to ensure prosecution.

This preliminary study combines the techniques of pyrolysis (Py)-GCMS and EA-irMS to discriminate between a set of smokeless powders. (Py)-GCMS is used to identify differences between relative ratios of the combustion products of the smokeless powder, while bulk stable isotopes of carbon (13C/12C) and nitrogen (15N/14N) in the residues are compared using EA-irMS. The data is interpreted using a combination of statistical techniques to ensure positive identification and discrimination between all smokeless powder samples investigated in the study.




Cl and O isotopic characterisation of perchlorate: lessons learnt mutually between Explosives and Environmental applications

 


Max Coleman


University of Reading and NASA Jet Propulsion Laboratory
 


The impetus to develop a method for isotopic analysis of Cl in perchlorate came from the need to characterise explosives. This led to the environmental application of the method to the problem of small amounts of perchlorate in groundwater. Environmental applications drove further developments: ability to analyse trace amounts, oxygen isotope characterisation (δ18O and δ17O) and quantification of the isotopic effect of microbial reduction. For explosive forensic use, solid perchlorate now can be characterised by its chlorine and oxygen isotope compositions and heterogeneity within and between crystals. There is now the possibility to apply the method to trace perchlorate. If there is sufficient total material for analysis it can be concentrated using a specially developed bifunctional anion exchange resin. Especially for trace perchlorate, there is the possibility of microbial change of the initial isotope signature by bacteria, which are almost ubiquitous. We have now measured this large isotope fractionation effect for oxygen (~ -30‰) as well as for chlorine. This could provide a forensic challenge to isotopic evidence of source of material, but there is a counter, an easily applied test for expression of the functional gene used in microbial perchlorate reduction. Thus the two applications have proved to be mutually supportive.

 

Evaluation of preliminary isotopic analysis (13C and 15N) of explosives
A likelihood ratio approach to assess the links between semtex samples through a Bayesian framework


Georges Pierrini


Insitut de Recherche de la Gendarmerie Nationale, France


Currently the use of isotopic ratio as corroborative evidence in criminal trials is explored. Beyond the analytical challenges that have been reported elsewhere, the crucial issue of the interpretation of analytical results in a fair and balanced way remains poorly documented.

The aim of this presentation is to propose a likelihood ratio approach for the evaluation of stable isotope data acquired from semtex samples which takes place into a Bayesian framework.

It is proposed the evaluation of these data using a likelihood ratio framework that has received increasing attention in the past 15 years in all areas of forensic science. The main advantage of the approach is that it forces the scientist to assess the respective likelihood of the data under a competing set of propositions. That mechanism allows a balanced assessment of the contribution of the findings in the criminal proceeding.
It is proposed to explore data with common statistical test before introducing three continuous models.




Interpretation of 1st FIRMS Inter-laboratory IRMS analytical exercise 2004


Miss D H Wakelin, Mr S P Doyle, Miss C M Lock


Forensic Explosives Laboratory, Defence Science Technology Laboratory (Dstl), Fort Halstead, Sevenoaks, Kent, TN14 7BP


The FIRMS Network agreed at the May 2003 workshop that an inter-laboratory analytical exercise should be carried out in order to establish a baseline for the precision of results obtained using different IRMS methods in different global laboratories. This exercise took place during May – July 2004.

Two samples, ‘Flour A’ and ‘Sugar A’ were prepared by Dr Steven Brookes of Iso-Analytical Ltd and were distributed to all participating laboratories by Dr Matthew Beardah of the Forensic Explosives Laboratory.

‘Flour A’ required analysis for carbon-13 and nitrogen-15 with each isotope being measured separately i.e. no dual carbon/nitrogen, and ‘Sugar A’ required analysis for carbon-13. Each laboratory was required to measure each sample 10 times for the relevant isotopes against their own in-house standards, and were also advised to measure traceable international references as controls.

When reporting the data, participants were asked to provide the carbon-13 and nitrogen-15 values in terms of δ13C vs V-PDB (‰) and δ15N vs air (‰) respectively. They were also asked to provide details and values of the control samples measured, details of the in-house reference materials used and their assigned delta values and brief details of the instrumentation used.

An interpretation of the resulting data from this 1st inter-laboratory exercise will be presented for discussion.




A new Concept for isotope ratio monitoring LC/MS


A. Hilkert, D. Juchelka, M. Krummen, R. Pesch


Thermo Electron (Bremen) GmbH, Barkhausenstr. 2, 28197 Bremen, Germany


A new interface for the on-line connection of a liquid chromatograph to a stable isotope ratio mass spectrometer has been developed and tested. The interface enables the 13C/12C determination of organic compounds. The carbon content of the analytes is converted into CO2 while the compounds are still dissolved in the liquid phase. This is accomplished by an oxidizing agent, such as ammonium peroxodisulfate. The CO2 is separated from the liquid phase and transferred to the mass spectrometer. It is shown that the whole process does not introduce an isotopic fractionation. The measured carbon isotope ratios are accurate and reproducible.

The Finnigan™ LC IsoLink is a completely new concept for isotope ratio monitoring LC/MS. First approaches for irm-LC/MS systems used a desolvating nebulizer or a moving wire system to separate the liquid phase from the sample before combustion. In the Finnigan LC IsoLink, the liquid phase is not removed from the sample prior to oxidation. The sample is oxidized still in the mobile phase followed by on-line separation of the CO2 from the liquid phase and transfer into the isotope ratio MS. In marked contrast to former approaches the processes in the LC IsoLink are quantitative and fractionation-free.

The principle of the measurement and first results for two different injection modes (direct injection and HPLC injection) on reproducibility, linearity and accuracy will be presented. Furthermore, first applications in the field of authenticity control of food and ingredients, investigation of the drugs and measurements of important compounds for biochemical studies will be shown.

diagram of irm-LC/MS system

Scheme of the irm-LC/MS system with the Finnigan™ LC IsoLink



Keynote Speech: Forensic applications of stable isotope analyses


James Ehleringer


SIRFER, Department of Biology, University of Utah, 257 South 1400 East Salt Lake City, UT 84112 USA


Stable isotope concentrations at natural abundance levels may prove useful in several areas related to forensics and to domestic and international terrorism. Today stable isotopes of carbon (13C/12C), nitrogen (15N/14N), oxygen (18O/16O), sulfur (34S/32S), and hydrogen (2H/1H) in both organic and inorganic compounds can be determined routinely using an isotope ratio mass spectrometer. These analyses can be performed on both bulk materials (organic and inorganic) or materials that have been purified from a mixture. Of particular interest in forensic science are applications of stable isotope ratio analyses where the information can be used to determine region-of-origin, authenticity, or relatedness of two or more materials of identical chemical composition. Stable isotope analyses have a rich history of application in the geochemical and biological; they are just now being more extensively applied to forensic sciences. In this talk I explore the utility of stable isotopes to determining region-of-origin in three key areas of forensic interest: (a) the geographic origins and movements of humans, (b) the manufacturing location of pathogenic microbes, and (c) origins of explosives recovered either as undetonated or detonated materials. Each of these cases highlight situations in which key information is recorded permanently in the stable isotopic composition of organic molecules that are of forensic interest.




Forensic Stable Isotope Signatures from Biological and Non-Biological Materials


Wolfram Meier-Augenstein


Environmental Engineering Research Centre, Queen’s University Belfast, Belfast, BT9 5AG, United Kingdom.


Stable isotope ratio analysis is well established in fields such as environmental science, geology, biology and oceanograpghy but has limited forensic applications to date. It has become more established in forensic fields such as food adulteration and the arts but recent advances in stable isotope technology have opened up a wide range of forensic applications.
Though the potential of using isotope signatures for forensic applications has been demonstrated by several research groups across the globe, applications using this tool as part of ongoing criminal investigations or forensically driven studies are still far and few between.

Here, we present isotope data, interest in which was triggered by two ongoing criminal investigations, a murder enquiry and a case of perverting the course of justice, conducted by the Police Service Northern Ireland (PSNI) as well as a forensically motivated study of household and car paints carried out by the Forensic Service Northern Ireland (FSNI).




Bulk and compound specific isotopic characterisation of illicit drugs and drug packaging


Fay Idoine, Jim Carter, Richard Sleeman


Mass Spec Analytical Ltd., Building 20F, Golf Course Lane,
PO Box 77, Filton, Bristol BS99 7AR

A number of seized heroin samples and their cling film packagings were studied. The heroin was visually similar, the colour suggesting an origin in southwest Asia (Afghanistan). The samples were found to comprise mixtures of natural opium alkaloids (codeine, acetylcodeine, morphine, mono- and diacetylmorphine, noscopine and papaverine). The purity of the DAM was found to range from approximately zero to seventy percent. The most common cutting agents were caffeine, detected in all but one of the samples, phenobarbital, diazepam and acetaminophen.

d2H, d13C, d15N and d18O analysis of the bulk heroin was able to distinguish between all but two of the seizures. However, bulk isotope ratios are readily affected by the addition of other components which may not be detectable by gas chromatography, e.g. proteins and sugars. Therefore, although bulk isotope analysis can establish links between seized samples it is not suitable for tracing a line of distribution from production to sale.

d2H and d13C GC-IRMS data did not distinguish these two samples, suggesting that they originated from the same importation. Applying data reduction techniques, d2H of caffeine and DAM was found to provide greater discrimination than the d13C of the other components. Combining d2H and d13C data for DAM and caffeine enabled the majority of samples to be distinguished.

The use of Solid Phase Extraction to recover trace heroin samples was found to produce degradation of the DAM to 0-6-MAM, 0-3-MAM and morphine. SPE was also found to caused isotopic fractionation of both the opiate molecules and the cutting agents, with respect to both d2H and d13C. Liquid-liquid extraction (from a phosphate solution pH 6.0) was less destructive and no degradation of DAM or MAM was observed. Storage time of solutions was found to effect the carbon but not the hydrogen isotopic composition.

A range of commercially available cling films were analysed and found to divide into two broad groups, poly(vinyl chloride) and polyethylene. The majority of these samples were distinguishable by d13C. All the case studies were correctly grouped according to the heroin seizure from which they were obtained by d13C. However, it was necessary to employ multivariate analysis, incorporating d2H, d13C and d18O to fully distinguish the samples from each other. Although GCMS data suggested that material leached between the heroin and the cling film no effect on the bulk isotopic properties of heroin was observed following a period of storage.




Comparison of Cocaine and MDMA Samples by Stable Isotope Ratio Mass Spectrometry (IRMS)


Helmut Neumann and Thomas Holdermann


Bundeskriminalamt, Forensic Science Institute, Central Chemistry Laboratory (KT12),
D-65173 Wiesbaden, Germany


The presentation starts by explaining the mission of the Federal Criminal Police Office (Bundes­kriminalamt) and its Central Chemistry Laboratory in the police system of Germany.

In 1996 an isotope ratio mass spectrometer with an elemental analyzer was installed at the BKA Central Chemistry Laboratory. The isotope ratio measurements have been focused on the determination of carbon and nitrogen values. Tracing back of the determined delta (d) - values to international standards and the multiple analysis of a quality control check sample in each sequence ensure accurate and reproducible data.

After initial tests for the comparison of explosives (e.g. TNT samples of different origin) and of polymers (polyurethane foams) we concentrated on the comparison of cocaine and MDMA samples. Besides cocaine samples from big seizures in Germany we were fortunate to get samples from South America with documented origin for isotopic analysis. Concerning the major origin countries Bolivia, Colombia and Peru we observed an interesting shift of the d15N values to higher numerical values for the Colombian samples of 2000 in comparison with the samples from 1985.

Also for MDMA samples the δ15N isotopic values proved to be very valuable for sample comparison because of the large range we and others found for this parameter. A maximum of samples was detected around a δ 15N value of +1. Finally the application of the developed method for comparison of MDMA samples in a proceeding of a Regional Superior Court is presented. In this case a judgement about the operation of a big clandestine laboratory for the production of MDMA had to be made. The result from sample comparison by IRMS was the crucial evidence to prove that at least two batches of MDMA had been produced.

Future work will be directed to the exploration of gas and liquid chromatographic devices coupled to the IRMS instrument and the use of hydrogen and oxygen isotopic ratios for sample comparison in different forensic areas.




Isotopic and trace element analysis of human tissues for provenance determination purposes


Kenneth Pye,


Kenneth Pye Associates Ltd.


Abstract - TBC




LA-ICP-MS and IRMS investigations on packaging and duct tapes


Shirly Montero PhD, Ing. Wim Wiarda, Ing. Peter de Joode and Gerard J.Q. van der Peijl PhD


Netherlands Forensic Institute (NFI), PO Box 24044, 2490 AA The Hague, The Netherlands


Results are presented for packaging and duct tape comparison experiments using the forensic IRMS (Isotope Ratio Mass Spectrometry) technique. Results will be discussed and compared with results using other new forensic techniques such as solution nebulisation ICPMS and LA-ICPMS. Time permitting some other forensic applications (polypropylene rope, paper, burnt polymers, isolation material from electricity wire) from our NFI forensic practice will be discussed.

Introduction.
Brown packaging tape until recently was encountered in 60% of the violent crimes (murder, rape) committed in The Netherlands where tape is found at the crime scene. Nowadays gray duct tape is encroaching on the crime scene. Normally, the forensic scientist is requested to compare the tape retrieved from the crime scene with tape found with a suspect. At the NFI a combination of visual investigation (physical fit, tape dimensions, colour, morphology), FT-IR and XRF is used routinely to compare tapes. FT-IR can be used to identify the type of glue and backing polymer. A combination of visual comparison and XRF analysis generally suffices to discriminate between different tape products but cannot be used for further discrimination between different batches of one brand of tape product.
Solution ICPMS In earlier studies, the more varying adhesive layers of packaging tapes were investigated using both solution nebulisation ICPMS (Inductively Coupled Plasma Mass Spectrometry) and LA-ICPMS. With these techniques trace levels of elements are detected and identified. Solution nebulisation ICPMS experiments, especially, produced very discriminatory results. An Element (ThermoFinnigan) HR-ICPMS was used. For solution nebulization measurements, the glue (ca 50 mg) was first separated from the backing material through mobilisation in a solvent (methanol, hexane) and then digested in a microwave oven (75 bar, 290ºC) in a nitric acid/H2O2/H2O mixture. For the three investigated different packaging tape brands, commercial samples from the same tape product acquired at different times from one commerical outlet and at one time from different outlets could be discriminated on the basis of the solution nebulisation ICPMS results whereas visual comparison and XRF (macro elements) were not sufficient for discrimination between these tapes.

LA ICPMS Laser ablation measurements on intact packaging tape samples of the above rolls were made directly on the glue layer using a 266 nm Nd:YAG laser. Packaging tape samples were placed in the sample chamber and the glue layer was laser ablated. Volatiles and aerosols produced in this way were swept into the ICPMS system (low mass resolution mode). As optimal values a laser pulse energy of 2 mJ, a pulse repetition rate of 10 Hz, a spot size of 80 µm and an ablation distance (lateral shift of laser spot) of 30 µm were chosen. Laser spots were therefore partially (50 µm) overlapping. Signals were integrated for 60 seconds over a grid area of 1 mm2. Similar conditions were used for duct tape investigations where both the glue and the backing layers can be investigated independently.

LA ICPMS results for the different rolls of one brand of packaging tape demonstrate for each brand that discrimination power is sufficient to discriminate the rolls but is somewhat lower relative to solution nebulization results. In these experiments all tapes could be discriminated. Upon repetition of the LA ICPMS experiments for the three different rolls of one brand on another day the same distribution pattern is observed. The exact location of the distribution pattern is not exactly the same however, reflecting in our opinion variations in laser pulse energy observed during these specific experiments.

IRMS (Isotope Ratio Mass Spectrometry) focuses on stable isotope ratios of abundant elements in the samples such as H, C and O (O only in the oxygen containing materials). Isotope ratios used were 2H/1H, 13C/12C and 18O/16O. Tape samples were analysed for us at Iso-Analytical Ltd (Sandbach, Cheshire CW11 3HT, UK). The IRMS used was a Europa Scientific Geo 20-20 instrument. All samples were measured in triplicate. Tape samples were prepared for analysis by separating the glue and backing layers which were analysed separately. Also complete tape samples, without further sample preparation, were analysed.
IRMS conditions Hydrogen isotope analysis (ca. 6 mm2 tape sample) was conducted by total conversion at 1080 °C in a quartz reactor lined with a glassy carbon film, filled to a height of 180 mm with glassy carbon chips. Hydrogen was separated from other gaseous products on a GC column packed with molecular sieve 5A at a temperature of 30 °C. A Faraday cup collector array was used to monitor the masses 2 and 3. Carbon isotope analysis (ca. 5 mm2 tape sample) was conducted by EA-IRMS using a combustion furnace, reduction furnace and GC oven temperature of 1000, 600 and 90 °C, respectively. Oxygen isotope analysis (ca. 22 mm2 tape sample) was conducted by total conversion at 1080 °C in a quartz reactor tube lined with a glassy carbon film, filled to a height of 170 mm with glassy carbon chips and topped with a layer (10 mm deep) of 50 % nickelised carbon. Carbon monoxide and nitrogen were separated on a GC column packed with molecular sieve 5A at a temperature of 50 °C.

Excellent IRMS results were obtained. For the three different packaging tape brands investigated, commercial samples from the same packaging tape product acquired at different times from one commerical outlet and at one time from different outlets could be discriminated on the basis of a combination of the δ13C and δ2H results. Alternatively, for the two oxygen containing packaging tape brands, samples could easily be discriminated using a combination of the δ13C and δ18O results. This could be done using either results for the full tape, the glue or for the backing material. Especially the latter is of great value since this means that, together with the glue, all other debris (blood, hairs, fibers) can easily be removed. The results even indicate potential for within production batch discrimination. For duct tape materials also good discrimination is obtained although we did not yet investigate intra production batch materials.

Discussion Comparing IRMS with ICPMS an interesting characteristic is that whereas ICPMS focuses mostly on trace elements and is therefore inherently more sensitive to contamination, IRMS focuses on the abundant elements (H, C and O) in organic chemical samples and therefore is less sensitive to contamination problems. The above results demonstrate the strong potential of novel forensic techniques such as (LA-)ICPMS and IRMS for forensic investigation of packaging and duct tapes. We have found this is only one example of a wider forensic application of these techniques for forensic material comparisons.




Accelerant / Explosive Detection Canines and IRMS: Working together to advance both science and public safety


Daren Davies


Integriguard, Topeka, Kansas


This presentation serves to help bring about a better working relationship through better understanding of the valued relationship between Accelerant / Explosive Detection Canines and Isotope Ratio Mass Spectrometry (IRMS). A more informed appreciation of the unique attributes that each offer to the field of forensic sciences serves to not only advance science, but to also better protect and safeguard public safety.

IRMS technology used to identify isotopic ratios of various compounds, including organic explosive material (both low and high order), inorganic compounds (such as nitrates), and accelerants (such petroleum based ignitable liquids) creates demonstrative evidence for both court presentation, but also supports the effective usage of K-9 service detection work.

Some of the latest work and research conducted throughout the world, focusing primarily upon the United Kingdom and the United States will focused upon and discussed. Recent advances in forensic sciences have well demonstrated the effective relationship between Accelerant / Explosive Detection Canines and Isotope Ratio Mass Spectrometry (IRMS).




Isotopic Measurements on Nuclear Materials at Environmental Levels Using Multicollector TIMS


Chris Poile and Claudie Black


AWE Aldermaston, UK


Thermal ionisation mass spectrometry has been used at AWE for over forty years to measure isotopic ratios of nuclear materials. Over the years sample sizes have become progressively smaller and now minor isotopes in the attogram range can be measured using the latest ion counting instruments.

Traditionally, isotope ratios are determined using a peak jumping method in which one detector collects data as the magnet is scanned across each of the isotope masses in sequence. Whilst very accurate, this method is inefficient, and results in the loss of data. The advantage of using multiple detectors spaced one mass unit apart is that all available data is collected, which is essential when dealing with trace amounts.

In August 2003 a Thermo Triton mass spectrometer was installed at AWE, this instrument has multi ion counting capability. Seven micro Secondary Electron Multipliers and three micro faradays on movable platforms and one fixed SEM enable eleven masses to be measured simultaneously. Results of this work to date are presented.




LA ICPMS and IRMS isotopic and other investigations in relation to a safe burglary


Shirly Montero PhD, Ing. Wim Wiarda, Ing. Peter de Joode and Gerard J.Q. van der Peijl PhD


Netherlands Forensic Institute (NFI), PO Box 24044, 2490 AA The Hague, The Netherlands


Safe wall filling material was released when an old safe was burglarized. During a search at the suspect’s residence, visually similar material (mixture of glass like particles and sawdust) was retrieved from a plastic bag containing money. Small iron-containing particles were also retrieved from both samples. The safe wall filling material was found to consist of a mixture of alum or potassium alum (KAl(SO4)2.12H2O) crystals (XRF/XRD) and sawdust (vis, FT-IR). All three material fractions (alum, sawdust, metal particles) were intercompared for the two samples.

The material combination of alum and sawdust appears very rare. Information was collected on the history of its use as safe wall filling, alternative applications of this material combination and how often Dutch police organisations encountered this material in the last two years. It was concluded that this material combination was only used for safe wall filling in the period before the 2nd World War, that no alternative applications were found and that no police organisation reported encountering this material combination.

Alum investigations:
The glass like particles in both material samples were classified as alum. ICP AES results were obtained using a PE OPTIMA 3000 instrument. Apart from the major elements Al and K (S was not measured) Cr and Tl were observed at similar levels in both samples. Other elements observed (Fe, Sr,..) were present at much higher concentrations in the red-brown powder so that these are not confidently attributed to the alum samples.

LA ICPMS results using a PE ELAN 6100 DRC PLUS instrument were obtained on freshly cleaved inner alum crystal surfaces. Elements observed in both samples are Mg, Si, P, Ti, Cr, Cu, Zn, Ga, Rb, Sr, Sn, Ba, Tl and Pb.

IRMS services were provided by Iso-Analytical Ltd (Sandbach, UK) using standard methods on a Europa Scientific Geo 20-20 instrument with an EA-IRMS interface. Different isotope ratios were measured in separate experiments using different experimental configurations of the instrumentation. The mean d34S values for the suspect and crime scene alums (both 2.2 ± 0.1 ‰, n = 6) were undistinguishable using an experimental uncertainty of 0.24 ‰ (2s). This is compared to a variation range of -3.9 to +30.6 ‰ as reported [1] for d34S values obtained for a large number of alum minerals from various locations throughout the world and a variation range of 1.7 to 9.8 ‰ for a small test set of four different alum samples as obtained from alum suppliers in the Netherlands.

Sawdust investigations:
The suspect and crime scene sawdust samples are visually similar and exhibit the same red brown colour. A mixture of wood species, both soft and hard woods, was observed in both samples during botanical species investigations at the National Herbarium of the Netherlands. Over five species were identified in the suspect sample.


IRMS isotope ratios d2H, d13C en d18O for both the suspect and the crime scene sawdust fractions agree within the experimental uncertainty (2s, n=6). d13C=-25,71+ 0,15 is e.g. compared to a variation range of -32 to -22 ‰ as reported for the d13C values of C3 plants [2]. Applicability of this information for the local situation is tested by collecting a limited set of sawdust samples in the Netherlands market and analysing these by IRMS. For d13C e.g. a variation range of -23 to -28 ‰ is measured.

Metal particles investigations:
In both samples many minute metal particles were observed that were magnetically separated from the sample matrix. Corresponding variations in morphology of the particles (round balls of various sizes and curved lint like particles) indicate that metal particles in the two samples were formed through a similar process consistent with abrasive cutting of a safe [3]. μ-XRF (EAGLE) results for the round balls and lint particles show a high abundance of Fe as well as the presence of other elements such as Al, Si, P, S, Mn and Cu. Similar results were obtained for the fine metal particle fractions in both samples.

Conclusions:
Combining the information from the various sources and the analytical results for the various material fractions (sawdust, alum, metal particles) provides a strongly discriminating method to compare the (combination of) material fractions as found in the two samples at the suspect’s residence and at the scene of crime.

References
Rye, R.O., P.M. Bethke and M.D. Wasserman, The Stable Isotope Geochemistry of Acid Sulphate Alteration, Economic Geology 87 (1992) 225-262
Cerling, T. E., J. M. Harris, B. J. MacFadden, M. G. Leakey, J. Quade, V. Eisenmann and J. R. Ehleringer, Global change through the Miocene/Pliocene boundary. Nature 389 (1997) 153-158.
Zeichner A., G. Feingold and E. Landau, “Abrasive cutting of a safe: a case study”, Journal of Forensic Science 38 (1993) 1516-1522




The Role of Stable Isotopes in Human Identification


I. Fraser, Professor R.M. Kalin, Dr. W. Meier-Augenstein


The School of Civil Engineering, Queen’s University Belfast BT9 5AG, Northern Ireland


A new technique is required to provide information in cases where DNA methods fail to yield the identification of an individual, or situations where authorities need to determine the recent geographical history of people. This maybe in relation to individuals detained either on suspicion of terrorism or otherwise gaining illegal entry to the UK. One proposed solution is the use of Isotope Ratio Mass Spectrometry (IRMS).

There is known to be a link between the isotopic signal of dietary components and the corresponding body tissue isotopic values. This study aims to devise and refine a non-invasive method of analysing human material such as hair, nail and breath using multiple isotopes.

Hair and nail samples were collected from British and non-British volunteers at Queen’s University Belfast every two weeks for a period of five months. Samples were analysed using EA IRMS and isotope ratios determine for 13C/12C, 15N/14N, 2H/1H, 18O/17O and 34S/32S.
The results of this longitudinal study illustrate the natural variation in the isotopic abundance of samples. Differences were detected between individuals of different ethnic origins, all of whom have been resident in Belfast for a minimum of one year. Changes in the isotopic composition of certain samples collected from subjects were found to correspond to changes in their geographical location or diet. This suggests that fluctuations in an individual’s diet and environment are reflected in their tissue and can be detected by IRMS.

In addition, the results of a storage experiment and a preliminary geographical database are presented.

Provisional data suggest that IRMS has a potential role in determining the geographical history of an individual, thus assisting intelligence-led policing.




The Application of EA/ Isotope-Ratio Mass Spectroscopy in the Forensic Analysis of White Architectural Paints


Lisa.J.Reidy (1), Prof.R.M.Kalin (1), Dr W.Meier-Augenstein (1), J.Armstrong (2)


(1) Queens University of Belfast, (2) Forensic Science Northern Ireland


The use of isotope ratio mass spectroscopy (IRMS) provides additional information to complement existing techniques in paint analysis. Variability in paint samples is often due to binder and pigment type within the sample. The most common resin to be used in decorative paints is drying oil alkyd resin which incorporates soybean oil and vinyl acrylic based latexes, these are commonly encountered as solvent based paints.
Utilising modern day analytical methods the forensic scientist can answer the question as to whether the two paint samples appear the same, but can not conclusively say that they both originate from the same source.
IRMS allows minute changes in the isotopic composition of a given compound to be detected, and these changes may be unique to each sample. Consequently an isotopic fingerprint can be generated allowing more discriminating power when comparing samples.

Twenty eight (28) different white architectural paints were analyzed using IRMS to determine isotopic composition. In addition, variations in application, curing time and thickness were also investigated to determine sample variability. EA -IRMS analysis results indicated that this method aids in the discrimination of paint samples. The parameters of thickness and homogeneity of the sample indicated no significant difference in the results obtained proving that IRMS may be a valid method of distinguishing between different paint samples. This provisional data shows that IRMS can make an important contribution to the analysis of paint in a forensic situation.




Isotope Analysis of Safety Matches


Nicola Farmer, Dr. Wolfram Meier-Augenstein, Dr. Alastair Ruffell


Queen’s University Belfast, Northern Ireland


Isotope ratio mass spectrometry (IRMS) has been used in combination with two other techniques, X-ray diffraction (XRD) and observation by microscopy (standard binocular microscope and petrographic microscopy), to find out how well individual safety matches can be matched to their original box or manufacturer. To the best of our knowledge, this is the first case where these techniques have been combined for the forensic analysis of safety matches.

Safety matches from around the world have been collected, analysed and compared to determine mineralogy of match heads by XRD, isotopic composition of wood by IRMS, and wood structure by microscopy. Preliminary data show that little variation seem to exist between safety matches from the same box, while safety matches allegedly produced by the same company but marketed under differing brand names can, in some cases, be discriminated, especially in combination with information gained from XRD and microscopy. We conclude that this methodology should be tested and developed further since it may provide important intelligence in criminal investigations where safety matches retrieved both from a crime scene and a suspect are to be compared.
 




High resolution and laser ablation MC-ICPMS, a new technique for δ34S measurements


Peter Evans (1), Robert Clough (2), David Carter(1) and Ciaran O’Connor(3)


(1) LGC, Queens Road, Teddington, Middlesex TW11 0lY United Kingdom
(2) University of Plymouth, Drakes Circus, Plymouth, PL48AA United Kingdom
(3) Loughborough University, Leicestershire, LE11 3TU United Kingdom


A precise, accurate and reliable method for the determination of sulfur isotopic ratios by multi-collector ICPMS is presented. All measurement were performed using a ThermoFinnigan Neptune. Silicon (Si) is used to correct for instrumental mass discrimination and high-resolution measurements are used overcome oxygen based interferences. Internal precision of <0.02 % 2s is possible for 25 x 4 second integrations.

Results are presented using the conventional δ34S value with a statement of precision alongside a full uncertainty budget of the absolute 34S/32S ratio taking into consideration the uncertainty of the silicon value, standards and repeatability. The use of silicon to correct for mass discrimination reduces the reliance upon artefact standards for defining variations in the sulfur ratio.

The efficacy of the technique is first explored using a range of pure sulfur standard solutions. Gravimetric addition of a 34S enriched spike was used to synthetically replicate a range of δ34S values. The gravimetric and measured results exhibit a correlation of R2 >0.999. Repeat measurements were also made after adding Na, Mg and Ca salts to the sulfur standard. No significant deviations in the mass discrimination corrected ratio were observed. The resolving power of the technique, taking into consideration all uncertainty components, is assessed to be better than 1 ‰.

The efficacy of the technique is first explored using a range of pure sulfur standard solutions traceable to a solution of SRM8553 (Soufre de Lacq). Gravimetric addition of a 34S spike produces accurate and precise changes in δ34S. Standards that were spiked with varying levels of matrix elements (Na, Ca and Mg) do not vary the δ34S. From this it can be demonstrated that the effects of varying sample matrix upon mass discrimination are being fully accounted for by the silicon correction.

The new instrumental technique can be readily applied to aqueous samples. A suite of mineral and spring water samples representative of those currently on sale in the UK was measured for δ34S. The UK market for bottled waters is estimated to be £1 billion per year with significant differences in the price paid between brands. The δ34S of the samples varies from +22 to –13 ‰. The analysis time for individual samples is < 30 minutes – including sample preparation.

MC-ICPMS can also be coupled to a laser ablation source to provide solid sampling for δ34S. A New-Wave UP213nm Nd-YAg laser. Si was added on-line using a Cetac USN6000AT+ ultrasonic nebuliser. Laser ablation provides a rapid, low blank sampling technique with precision and accuracy comparable to more lengthy sample preparation methods. The technique is demonstrated using a suite of real and counterfeit tablets of Sildenafil (Viagra). Counterfeit samples differ from the real product by up to δ34S 10 ‰ illustrating to value of sulfur isotopic measurements in helping to identify the origins of illegally trade goods.