SHORT COMMUNICATION

Trace level triacetone-triperoxide identificationwith SPME–GC-MS in model systems

Anikó Kende & Ferenc Lebics &

Zsuzsanna Eke & Kornél Torkos

Received: 14 November 2007 /Accepted: 18 January 2008 /Published online: 4 March 2008# Springer-Verlag 2008

Abstract Triacetone-triperoxide is a high explosive mainlyused by terrorist groups. With the spreading of the recipe onthe Internet, increasing number of bomb attacks are beingreported worldwide using triacetone-triperoxide. A simpleidentification method is described using 100 μm polydi-methyl siloxane fibre solid phase microextraction and gaschromatography combined with spectrometry. The methodwas tested on various pre- and post-explosion models thatcan be collected in a house search or after a bomb attack.Sample preservation and stability was also examined.Identification of triacetone-triperoxide residues in post-explosion models was feasible 24 h after ignition, thedetection limit being 5 ng.

Keywords Explosive identification .

Triacetone-triperoxide . Solid phase microextraction .

Gas chromatography–mass spectrometry .Model systems .

Sample stability

Introduction

Triacetone-triperoxide (TATP) was discovered by Wolf-fenstein in 1895 [1], but because of its instability it wasrarely applied until the 1980s when terrorist groups startedusing it. It can be prepared of easily available ingredients[2] and cannot be detected by standard security systems orexplosive search trained dogs [3]. Because of its fast andeasy preparation it can be prepared on the spot, avoidingborder crossing. With the spreading of its recipe on theInternet the number of TATP explosion cases has increasedeven in such countries where earlier it was not character-istic. In some cases experimenting children prepared it,becoming causes of serious accidents [4].

TATP is a white crystal, usually characterised by itsterpen-like smell, but prepared of high purity ingredients itdoes not have any special odour. Its melting point is 94 °C,but sublimates at room temperature [2]. It is insoluble inwater, but soluble in numerous organic solvents (toluene,chloroform, acetone, dichloromethane, methanol) [5].When air-dry it becomes very shock, temperature andfriction sensitive. TATP is a slightly less powerful explosivethan TNT [3].

For the determination of TATP there has been reporteddifferent sample preparation methods, such as solventextraction [2], where the contaminated surface is tamponedwith a cotton wool soaked with cyclohexane. TATP is thenextracted from the cotton wool with clean cyclohexane andthe extract is filtered before gas chromatography (GC)analysis. There is a special headspace analysis methoddeveloped by Zitrin et al. [6], where the object of evidenceis put into a special plastic bag, tempered at 130 °C for15 min. Afterwards gas sample is taken from the bag. Thismethod was further improved by connecting a solid phaseadsorbent to the plastic bag, then air is pumped through it

Microchim Acta (2008) 163:335–338DOI 10.1007/s00604-008-0001-x

A. Kende (*) : Z. Eke :K. TorkosEötvös University,Pázmány Péter sétány 1/A,Budapest 1117, Hungarye-mail: kende.aniko@gmail.com

A. Kende : Z. EkeWessling International Research and Education Centre,Fóti út 56,1047 Budapest, Hungary

F. LebicsNSS Hungary,Budapest, Hungary

for 10 min, followed by the elution of TATP from theadsorbent. Solid Phase MicroExtraction using 85 μm polia-crylate fibre in unsuccessful preliminary experiments wasdescribed [6], but was successfully applied Muller et al. [7]when using polydimethyl siloxane (PDMS)/divinylbenzene(DVB) fibre. For the determination of TATP GC-FID [3],GC–mass spectrometry (MS) [5, 8] are used most frequently;or FT-IR in case of solid sample [3, 9, 10].

In this paper a simple identification method is described,using 100 μm PDMS fibre Solid Phase MicroExtractionand GC-MS. The procedure is adequate to identify TATP invarious matrices and sample types, in both pre- and postexplosion cases. The method was tested on model samplesthat can be collected in a house search or after a bomb attack.Sample preservation and stability was also examined.

Experimental

Risk statement of TATP

For our studies NSS Hungary provided the necessaryamount of TATP. If allowed to air dry, TATP becomes veryshock, temperature and friction sensitive, so if any amountis not used immediately, it should be kept under water. Thisway it is less explosive and can be stored long term withoutmajor decomposition. Scientific research of explosivematerials might be restricted to authorized laboratories insome countries.

Materials

Acetone super purity solvent was purchased from Romil(Cambridge, UK, http://www.romil.com), Solid PhaseMicroExtraction fibres: 7 μm PDMS, 30 μm PDMS,100 μm PDMS and 70 μm Carbowax/DVB were purchasedfrom Supelco (Budapest, Hungary, http://www.sigmaaldrich.com) [11]. 7.5 mL vials were used in SPME experiments.

Chromatographic conditions

For the measurements Agilent (Waldbronn, Germany,http://www.agilent.com) 6890N gas chromatograph and5973 mass spectrometer was used. The applied GC-MSconditions: Injector temperature 160 °C, splitless injectionwith 2 min split vent time. Column: HP 5 MS+ (Agilent,Waldbronn, Germany), 30 m×0.25 m×0.25 μm, tempera-ture program: 40 °C (2 min) 10 °C/min 250 °C (2 min).Carrier gas He, 0.4 bar, MS Interface temperature: 250 °C,solvent delay: 4 min, EI+ 70 eV, ion source temperature:230 °C. Software: MSD Chemstation. TATP eluted at9.11 min, its qualifier ions were 43, 58 and 222 in SIMmode.

Method optimisation

Identification of TATP was carried out from 100 μg mL−1

TATP solution in acetone. The main peaks of the obtainedmass spectra were 43 (100), 59 (55), 75 (54) and 222(33) [m/z (%)], correlating well with literature data.

Three fibre types were compared: 30 μm PDMS,100 μm PDMS and 65 μm PDMS/DVB. In order to selectthe most suitable SPME fibre the following samples wereprepared: few crystals of TATP were placed into a vial and3.5 mL distilled water was added. Each fibre was placed inthe headspace of a stirred aqueous suspension for 20 minabsorption time, then transferred to the injector of the gaschromatograph. After injection the fibres were conditionedfor 8 min at the injector temperature. Each fibre was re-runimmediately after conditioning to test for any possiblecarry-over.

Optimal absorption time was chosen in experimentsconducted with 100 μm PDMS fibre for 5, 10 and 20 minusing 100 μg mL−1 TATP aqueous suspension, stirringapplied.

Temperature dependence of the absorption was exam-ined at 25, 40, 60, 80 and 100 °C. The absorption wascarried out in a block heater, which did not allow samplestirring.

Model samples

In order to model possible evidences collected in an in-vestigation, different samples were prepared. These modelsincluded both pre-explosion – which could be collected i.e.in a house search – and post-explosion samples:

1. Few crystals of TATP in a closed vial, simulating anemptied but closed container.

2. TATP spilled on a tile and sampled after 2 days, whenTATP had sublimated to simulate any open surface,where TATP was handled. The tile was tamponed witha dry cotton wool, which was then placed into a vialand 3.5 mL distilled water was added.

3. 0.5 g mixture of soil and debris, containing 100 μg g−1

TATP was placed into a vial, simulating dry samplecollection in case TATP was strewn out on the field.

4. 0.5 g mixture of soil and debris, containing 100 μg g−1

TATP was placed into a vial, 3.5 mL distilled water wasadded, simulating sample collection applying distilledwater to prevent decomposition of TATP.

5. Approximately 0.5 g TATP was placed on a tile andignited. 1/3 of the surface of tile was tamponed with adry cotton wool right after igniting, another 3 h laterand the remaining part 24 h later. After sampling thecotton wool was placed into a vial containing 3.5 mLdistilled water.

336 Microchim Acta (2008) 163:335–338

6. Approximately 0.5 g TATP was placed on a tilecovered with soil and debris mixture and ignited. 1/3of the surface of tile was tamponed with a dry cottonwool right after igniting, another 3 h later and the last24 h later. After sampling the cotton wool was placedinto a vial containing 3.5 mL distilled water.

Models 5 and 6 simulate post-explosion sampling.For TATP identification in the models systems the

100 μm PDMS fibre was placed in the headspace of thevials for 10 min absorption time at room temperature.Model 1, 3 and 4 were further examined for a 10 daysperiod to observe sample stability.

Results and discussion

Based on the TATP peak area and peak shape in therespective chromatograms the 100 μm PDMS SPME fibrewas chosen for further experiments. For unambiguousidentification at low concentrations and reasonable time-frame for the measurements 10 min absorption time waschosen. In order to determine the optimal absorptiontemperature it was plotted against the peak area (Fig. 1).The curve reaches the maximum value at 60 °C. It maybe concluded that up to 60 °C the process determiningthe absorbed quantity is the migration of TATP from theaqueous phase to the headspace and absorption in thePDMS phase, while above this temperature the absorptioncapacity of the fibre starts to decrease. Detection limit ofthe method was calculated 5 ng as a signal to noise ratio of3 obtained in SIM mode.

Model 1 simulates an emptied but closed container,where the identification was based on the gas phaseresidues. Model 1 was further examined for a 10 daysperiod, while the TATP content has not changed signifi-

cantly. As a conclusion an emptied but closed containermay be adequate evidence even after a several days ofstorage.

Model 2 simulates any open surface, where TATP washandled in the preceding days. Though TATP sublimatesquickly, it can be identified 2 days later with tamponing thesurface.

Model 3 and 4 simulates TATP strewn out on the field.In the stability tests it was found that in Model 3 TATPconcentration decreases remarkably. At the end of the10 days period only one fifth of the original value wasdetected. This sample type is not reliable. Evaluation ofModel 4 showed that if distilled water was added to thesample, TATP could be identified in contaminated soil even6 days later without major decomposition (Fig. 2).

Both post-explosion models, Model 5 and 6 gavesatisfying results, since TATP was unambiguously identifi-able at each sampling time (Fig. 3).

10 20 30 40 50 60 70 80 90 1001.0x10

7

2.0x107

3.0x107

4.0x107

5.0x107

6.0x107

Peak A

rea

Absorption Temperature / ºC

Fig. 1 Temperature dependence of absorption

2 4 6 8 10

8.0x105

1.2x106

1.6x106

2.0x106

2.4x106

2.8x106

Number of days since sample preparation

Peak a

rea

2.0x107

4.0x107

6.0x107

8.0x107

1.0x108

1.2x108

Model 1

Model 3

Model 4

Fig. 2 Stability test of Model 1, 3 and 4

2000

4000

6000

8000

10000

12000

14000

16000

8 8.5 9 9.5 10 10.5 11 11.5 12

TATP 9.11

2000

4000

6000

8000

10000

12000

14000

16000

8 8.5 9 9.5 10 10.5 11 11.5 12

TATP 9.11

Time/min

Abundance

Fig. 3 Post-explosion models

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Conclusion

The developed method is easy to use and very simple: it doesnot require new sampling techniques on the field, and withthe addition of distilled water sample lifetime can beprolonged if it is necessary. Clear answer is achievable inonly 20 min including the short sample preparation and theGC-MS analysis with 5 ng detection limit. The method isproved to be utilizable in different case simulations.Application of the described method may help the work ofthe antiterrorist authorities whereas TATP can be detectedboth in pre-explosion samples collected in a house search,and in post-explosion samples collected after a bomb attack.

Acknowledgments This study was supported by Kromat Ltd. andNSS Hungary.

References

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6. Zitrin S (1998) The post explosion analysis of Triacetonetriper-oxide. In: Proceedings of the international symposium on theanalysis and detection of explosives. U.S. Government PrintingOffice, Washington, DC

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10. Schulte-Ladbeck R, Edelmann A, Quintas G, Lendl B, Karst U(2006) Application of selected-ion flow tube mass spectrometry tothe real-time detection of triacetone triperoxide. Anal Chem 78(23):8150

11. US Patent #5691206 (SPME)

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