This paper illustrates some preliminary investigations into using ICP-MS in combination with ET-AAS in the analysis of Ecstasy tablets. Results indicate that a combination of both techniques can show discriminating power between seizures. Descriptions of the modifications made to optimise the ET-AAS system are described

Littlejohn, D.

Nic Daeid, N.

Waddell, R.J.H.

English

Name not available

Preliminary studies identifying and quantifying trace metal impurities in illicit ecstasy tablets using atomic spectrometry techniques

University of Strathclyde Institutional Repository

Strathprints Institutional RepositoryNic Daeid, N. and Waddell, R.J.H. and Littlejohn, D. (2002) Preliminary studies identifying andquantifying trace metal impurities in illicit ecstasy tablets using atomic spectrometry techniques.Problems of Forensic Science, 42 (XLVII). pp. 413-417.Strathprints is designed to allow users to access the research output of the University of Strathclyde.Copyright c© and Moral Rights for the papers on this site are retained by the individual authorsand/or other copyright owners. You may not engage in further distribution of the material for anyprofitmaking activities or any commercial gain. You may freely distribute both the url (http://strathprints.strath.ac.uk/) and the content of this paper for research or study, educational, ornot-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to Strathprints administrator:mailto:strathprints@strath.ac.ukhttp://strathprints.strath.ac.uk/PRELIMINARYSTUDIES IDENTIFYINGAND QUANTIFYING TRACE METAL IMPURITIESIN ILLICIT ECSTASY TABLETS USING ATOMICSPECTROMETRY TECHNIQUESRuth J. H. WADDELL, David LITTLEJOHN, Niamh NIC DAÉIDForensic Science Unit, University of Strathclyde, Glasgow, United KingdomABSTRACT: This paper illustrates some preliminary investigations into usingICP-MS in combination with ET-AAS in the analysis of Ecstasy tablets. Results indi-cate that a combination of both techniques can show discriminating power betweenseizures. Descriptions of the modifications made to optimise the ET-AAS system aredescribed.KEY WORDS: Ecstasy; ICP/MS, ET-AAS.Problems of Forensic Sciences, vol. XLVII, 2001, 413–417Received 23 February 2001; accepted 15 September 2001INTRODUCTIONEcstasy (3,4-methylenedioxymethylamphetamine or MDMA) is a mem-ber of the amphetamine drug class and, in the UK, is controlled under theMisuse of Drugs Act 1971 and the Misuse of Drugs Regulations 1985. Ille-gally synthesised in clandestine laboratories, Ecstasy is predominantly pro-duced in tablet form, often with a distinctive motif. Profiling illicit drug sei-zures is essential in order to quantify the active constituent present and togather drug intelligence. Quantification has ramifications in subsequentcriminal proceedings while gathering intelligence may identify dealer-usernetworks. Currently, physical and chemical profiling relies on:– physical description,– presumptive tests,– TLC;– instrumental methods, generally chosen from HPLC, GC-FID, GC/MSor FT-IR.Various synthetic routes are known for Ecstasy production, the chosenroute often indicating the geographical origin of the seizure. In addition,route specific organic impurities are formed, which are identified by chro-matographic methods, normally GCFID or GC/MS. The resulting chromato-grams are known as “impurity profiles”. Seizures with the same organic im-purities may tentatively be linked to a common synthetic route although notnecessarily to a common laboratory. However, where the same impuritiesare present in similar concentrations, the seizures may have originated fromacommon batch.Elemental analysis of illicit seizures has the potential to augment or-ganic impurity profiling, with the possibility of providing evidence to sup-port both common route and batch links. Trace metals may be present in theseizure due to reducing agents/catalysts used during synthesis, leachingfrom vessels into the reaction mixture, contamination from diluents used to“bulk out” the tablets or external contamination, resulting from packagingand handling. In theory, seizures synthesised by the same route will containcommon trace metals, which should be present in similar concentrations ifthe seizures originate from common laboratories. Potentially, such linksmay be enhanced where similar ratios of drug-bound versus unbound metalare determined.In the literature, trace metal analysis of illicit heroin [3] and met-amphetamine [2] seizures has been reported, using inductively coupledplasma-mass spectrometry (ICP/MS) and flame atomic absorption spec-trometry (FAAS) for classification purposes. Little has been published forsimilar work involving Ecstasy seizures.AIMS AND OBJECTIVESThe aim of this work is to investigate the possibility of initially detectingtrace metal elements in illicit Ecstasy seizures by ICP/MS and quantifyingselected metals using electrothermal atomic absorption spectrometry(ET-AAS). The initial objectives are:1. To develop a reproducible method of sample preparation.2. To rapidly screen illicit Ecstasy seizures using ICP/MS to identify ele-ments of potential use in classification.3. To obtain reproducible detection of Pb in illicit Ecstasy seizures withminimal interference effects, using ET-AAS.EXPERIMENTAL METHODSSample preparation: Ecstasy tablets were powdered and digested(150 mg) in 10% HNO3 , using a CEM 2000 microwave and following the di-gestion programme outlined in Table I. Digests were diluted to give a finalconcentration of 1.5 mg tablet/ml in 1% HNO3.414 R. J. H. Waddell, D. Littlejohn, N. Nic DaéidA Sciex Elan 6000 ICP/MS instrument, set to the default parameters,was used to analyse the Ecstasy tablet digests. A UNICAM 929 ET-AASSpectrometerwas used to detect Pb in the tablet digests.TABLE I. MICROWAVE DIGESTION PROGRAMMEStage 1 2 3Power [%] 60 60 60Pressure [psi] 40 180 150Time [min] 10 10 10Time at pressure [min] 5 5 5Using matrix-matched standards, linearity over the concentration range0 to 30 ng Pb/ml was established and the regression equation and co-efficientof the calibration graph were determined. Digested tablets were analysed intriplicate and quantified, expressing the Pb concentration determined as mgPb/g tablet in the original digest. In addition, a L’Vov platform was insertedinto the furnace tube to investigate the benefits of platform atomisation overtube wall atomisation. The optimised furnace temperature programme forplatform atomisation is presented in Table II.TABLE II. OPTIMISED FURNACE TEMPERATURE PROGRAMME FOR PLATFORMATOMISATIONStage Temp [°C] Time [s] Ramp [°C/s] Gas typeGas flow[ml/min]Dry 1 80 20 10 Ar 200Dry 2 150 40 2 Ar 200Pyrolysis 700 30 50 Ar 200Atomisation 2000 3 > 2000 Ar 0Clean 2600 2 >2000 Ar 200RESULTS AND DISCUSSIONAnalysis by ICP/MS indicated significantly higher concentrations of Pb,Cu and Zn in the tablet digests compared with blank digests, as illustratedin Figure 1.Pb was initially chosen for quantification by ET-AAS, due to its apparentease of analysis. Using tube wall atomisation, there was poor recovery of Pb,especially at low concentrations (10 ng Pb/ml). However, with a L’Vov plat-form in place, improvements in recovery of up to 20% were obtained. For4 different seizures, the calculated mean Pb concentrations ranged from1.8 mg Pb/g tablet to 2.9 mg Pb/g tablet. Yet, despite platform atomisation,background absorbance was observed on the sample absorption profilesPreliminary studies identifying and quantifying trace metal impurities in illicit Ecstasy tablets... 415416 R.J. H. Waddell, D. Littlejohn, N. Nic Daéid0510152025303540B Cu Zn I PbBlankSample 1Sample 2Sample 3Fig. 1. Concentration of selected elements detected by ICP/MS.Fig. 2a. 10 ng Pb/ml standard solution.Fig. 2a. Sample NND 143 (1.5 mg/ml).(Figure 2), indicating that the interference effect had not been fully elimi-nated. This was further supported with a spike and recovery experimentwhere Pb recoveries were found to be outwith the acceptable 95%–105%range[1].CONCLUSIONS & FURTHER WORKICP/MS analysis proved to be effective in rapidly screening tablet digeststo identify elements of potential use in chemical profiling. Additionally,ET-AAS analysis was successful in detecting low levels of Pb in acid digestedEcstasy tablets. However, in spite of platform atomisation, an interferenceeffect continued to be present, as indicated by Pb recoveries which wereoutwith the acceptable 95%–105% range. The work has illustrated the po-tential benefits of trace metal analysis to enhance conventional profilingmethods although the problem of interference effects remains to be fully ad-dressed.In terms of further work, numerous possibilities are available and, per-haps those of most interest include the analysis of a number of large Ecstasyseizures (which are known to be different from HPLC and GC/MS analysis)by ICP-MS to assess differences in the metals present and concentrations ofeach. To improve Pb recovery at low concentrations by ET-AAS and to inves-tigate the use of alternative matrix modifiers such as palladium are also oninterest. Quantification of the Pb concentration in a number of large Ecstasyseizures and, in combination with HPLC and GC-MS data, attempting tolink seizures and expanding the ET-AAS technique for the detection of othertrace metals indicated as potentially discriminating by ICP/MS analysis arebeing undertaken.Acknowledgements:Thanks to David Lyon for carrying out the ICP-MS analysis and also to the Univer-sity of Strathclyde for providing financial assistance in funding this research.References:1. L e e M., Analytical method development in graphite furnace atomic absorptionspectrometry, UNICAM Analytical Systems Furnace Course Manual.2. M a r u m o Y., I n o u e T., S e t a S., Analysis of inorganic impurities in seizedmetamphetamine samples, Forensic Science International 1994, vol. 69,pp. 89–95.3. M y o r s R., W e l l s R. J. , S k o p e c S. V. [et al.], Preliminary investigation of her-oin fingerprinting using trace element concentrations, Analytical Communica-tions 1998, vol. 35, pp. 403–410.Preliminary studies identifying and quantifying trace metal impurities in illicit Ecstasy tablets... 417

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M a r u m o Y., I n o u e T., S e t a S., Analysis of inorganic impurities in seized metamphetamine samples,

Myors R.,Wells R.J.,Skopec S.V.[etal.],Preliminaryinvestigationofheroin fingerprinting using trace element concentrations, Analytical Communications

o r s R., W e l l s

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Preliminary studies identifying and quantifying trace metal impurities in illicit ecstasy tablets using atomic spectrometry techniques

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