A colorimetric sensor array for detection of triacetone triperoxide vapor

Triacetone triperoxide (TATP), one of the most dangerous primary explosives, has emerged as an explosive of choice for terrorists in recent years. Owing to the lack of UV absorbance, fluorescence, or facile ionization, TATP is extremely difficult to detect directly. Techniques that are able to detect generally require expensive instrumentation, need extensive sample preparation, or cannot detect TATP in the gas phase. Here we report a simple and highly sensitive colorimetric sensor for the detection of TATP vapor with semiquantitative analysis from 50 ppb to 10 ppm. By using a solid acid catalyst to pretreat a gas stream, we have discovered that a colorimetric sensor array of redox sensitive dyes can detect even very low levels of TATP vapor from its acid decomposition products (e.g., H(2)O(2)) with limits of detection (LOD) below 2 ppb (i.e., <0.02% of its saturation vapor pressure). Common potential interferences (e.g., humidity, personal hygiene products, perfume, laundry supplies, volatile organic compounds, etc.) do not generate an array response, and the array can also differentiate TATP from other chemical oxidants (e.g., hydrogen peroxide, bleach, tert-butylhydroperoxide, peracetic acid).     

Decomposition of triacetone triperoxide is an entropic explosion

Both X-ray crystallography and electronic structure calculations using the cc-pVDZ basis set at the DFT B3LYP level were employed to study the explosive properties of triacetone triperoxide (TATP) and diacetone diperoxide (DADP). The thermal decomposition pathway of TATP was investigated by a series of calculations that identified transition states, intermediates, and the final products. Counterintuitively, these calculations predict that the explosion of TATP is not a thermochemically highly favored event. It rather involves entropy burst, which is the result of formation of one ozone and three acetone molecules from every molecule of TATP in the solid state.     

Rapid trace detection of triacetone triperoxide (TATP) by complexation reactions during desorption electrospray ionization

Desorption electrospray ionization (DESI) mass spectrometry is used for rapid, specific and sensitive detection of trace amounts of the notorious explosive TATP present on ambient surfaces by alkali metal complexation in a simple spray technique.     

Analysis of oligomeric peroxides in synthetic triacetone triperoxide samples by tandem mass spectrometry

Oligomeric peroxides formed in the synthesis of triacetone triperoxide (TATP) have been analyzed by mass spectrometry utilizing both electrospray ionization (ESI) and chemical ionization (CI) to form sodiated adducts (by ESI) and ammonium adducts (by CI and ESI). Tandem mass spectrometry and deuterium isotopic labeling experiments have been used to elucidate the collision‐induced dissociation (CID) mechanisms for the adducts. The CID mechanisms differ for the sodium and ammonium adducts and vary with the size of the oligoperoxide. The sodium adducts of the oligoperoxides, H[OOC(CH₃)₂]_nOOH, do not cyclize under CID, whereas the ammonium adducts of the smaller oligoperoides (n < 6) do form the cyclic peroxides under CID. Larger oligoperoxide adducts with both sodium and ammonium undergo dissociation through cleavage of the backbone under CID to form acyl‐ and hydroperoxy‐terminated oligomers of the general form CH₃C(O)[OOC(CH₃)₂]_xOOH, where x is an integer less than the original oligoperoxide degree of oligomerization. The oligoperoxide distribution is shown to vary batch‐to‐batch in the synthesis of TATP and the post‐blast distribution differs slightly from the distribution in the uninitiated material. The oligoperoxides are shown to be decomposed under gentle heating. Copyright © 2009 John Wiley & Sons, Ltd.     

Analysis of triacetone triperoxide (TATP) and TATP synthetic intermediates by electrospray ionization mass spectrometry

The explosive triacetone triperoxide (TATP) has been analyzed by electrospray ionization mass spectrometry (ESI-MS) on a linear quadrupole instrument, giving a 62.5 ng limit of detection in full scan positive ion mode. In the ESI interface with no applied fragmentor voltage the m/z 245 [TATP + Na](+) ion was observed along with m/z 215 [TATP + Na - C(2)H(6)](+) and 81 [(CH(3))(2)CO + Na](+). When TATP was ionized by ESI with an applied fragmentor voltage of 75 V, ions at m/z 141 [C(4)H(6)O(4) + Na](+) and 172 [C(5)H(9)O(5) + Na](+) were also observed. When the precipitates formed in the synthesis of TATP were analyzed before the reaction was complete, a new series of ions was observed in which the ions were separated by 74 m/z units, with ions occurring at m/z 205, 279, 353, 427, 501, 575, 649 and 723. The series of evenly spaced ions is accounted for as oligomeric acetone carbonyl oxides terminated as hydroperoxides, [HOOC(CH(3))(2){OOC(CH(3))(2)}(n)OOH + Na](+) (n = 1, 2 ... 8). The ESI-MS spectra for this homologous series of oligoperoxides have previously been observed from the ozonolysis of tetramethylethylene at low temperatures. Precipitates from the incomplete reaction mixture, under an applied fragmentor voltage of 100 V in ESI, produced an additional ion observed at m/z 99 [C(2)H(4)O(3) + Na](+), and a set of ions separated by 74 m/z units occurring at m/z 173, 247, 321, 395, 469 and 543, proposed to correspond to [CH(3)CO{OOC(CH(3))(2)}(n)OOH + Na](+) (n = 1,2 ... 5). Support for the assigned structures was obtained through the analysis of both protiated and perdeuterated TATP samples.     

Electrochemical detection of triacetone triperoxide employing the electrocatalytic reaction of iron(II/III)-ethylenediaminetetraacetate and hydrogen peroxide

An electrochemical method for the detection of triacetone triperoxide (TATP) is proposed and examined. In this method, TATP solutions were treated with 1.08 M HCl for 10 min releasing H₂O₂ and/or hydroperoxides. Subsequently, these peroxides undergo an electrocatalytic reduction through the Fe^II/IIIethylenediaminetetraacetate (EDTA) complex at a glassy carbon electrode. Cyclic voltammetric results indicate that no redox reaction was observed between Fe^IIEDTA and TATP. Acid treated TATP yielded voltammograms indicative of electrocatalysis of ROOH/HOOH reduction via Fe^II/IIIEDTA redox cycling. Chronoamperometric results yielded a detection limit of 0.89 μM for TATP and a sensitivity of 0.025 mA mM⁻¹. The influence of pH and O₂ interference on the analytical signal is briefly discussed.     

High-throughput walkthrough detection portal for counter terrorism: detection of triacetone triperoxide (TATP) vapor by atmospheric-pressure chemical ionization ion trap mass spectrometry

With the aim of improving security, a high‐throughput portal system for detecting triacetone triperoxide (TATP) vapor emitted from passengers and luggage was developed. The portal system consists of a push‐pull air sampler, an atmospheric‐pressure chemical ionization (APCI) ion source, and an explosives detector based on mass spectrometry. To improve the sensitivity of the explosives detector, a novel linear ion trap mass spectrometer with wire electrodes (wire‐LIT) is installed in the portal system. TATP signals were clearly obtained 2 s after the subject under detection passed through the portal system. Preliminary results on sensitivity and throughput show that the portal system is a useful tool for preventing the use of TATP‐based improvised explosive devices by screening persons in places where many people are coming and going. Copyright © 2011 John Wiley & Sons, Ltd.     

Vibrational spectroscopy of triacetone triperoxide (TATP): anharmonic fundamentals, overtones and combination bands

The vibrational spectrum of triacetone triperoxide (TATP) is studied by the correlation-corrected vibrational self-consistent field (CC-VSCF) method which incorporates anharmonic effects. Fundamental, overtone, and combination band frequencies are obtained by using a potential based on the PM3 method and yielding the same harmonic frequencies as DFT/cc-pVDZ calculations. Fundamentals and overtones are also studied with anharmonic single-mode (without coupling) DFT/cc-pVDZ calculations. Average deviations from experiment are similar for all methods: 2.1-2.5%. Groups of degenerate vibrations form regions of numerous combination bands with low intensity: the 5600-5800 cm(-1) region contains ca. 70 overtones and combinations of CH stretches. Anharmonic interactions are analyzed.     

Gas chromatography/mass spectrometry analysis of triacetone triperoxide (TATP) degradation products

Interest in the analysis and detection of triacetone triperoxide (TATP) and other organic peroxides has increased in recent years. Also of interest is the degradation and decomposition of the peroxides, not only to gain more detailed chemical information from organic peroxide samples, but also to investigate possible new procedures or mechanisms for chemical neutralisation. This report investigates the chemical degradation products of TATP after it has been treated with different acids within a sealed system over a period of 14 days. The samples were collected and analysed by solid-phase microextraction (SPME) and direct liquid injection gas chromatography/mass spectrometry (GC/MS). The results of the experiments indicate that the rate of chemical degradation of TATP and the products formed are dependent on the type of acid. The observed differences enables the type of acid used in the degradation process to be determined, provide complementary information to identify the presence of TATP, and possibly indicate new pathways that may be used to chemically neutralise TATP.     

Analysis of triacetone triperoxide by gas chromatography/mass spectrometry and gas chromatography/tandem mass spectrometry by electron and chemical ionization

The explosive triacetone triperoxide (TATP) has been analyzed by gas chromatography/mass spectrometry (GC/MS) and sub-nanogram detection limits are reported by ammonia positive ion chemical ionization (PICI), electron ionization (EI) and methane negative ion chemical ionization (NICI). Analysis by methane PICI and ammonia NICI gave detection limits in the low nanogram range. Analyses were carried out on (linear) quadrupole and ion trap instruments. Analysis of TATP by PICI using ammonia reagent gas is the preferred analytical method, producing low limits of detection as well as an abundant (greater than 60% of base peak) diagnostic adduct ion at m/z 240 corresponding to [TATP + NH4]+. Isolation of the [TATP + NH4]+ ion with subsequent collision-induced dissociation (CID) produces extremely low abundance product ions at m/z values greater than 60, and the m/z 223 ion corresponding to [TATP + H]+ was not observed. Density functional theory (DFT) calculations at the B88LYP/DVZP level indicate that dissociation of the complex to form NH4+ and TATP occurs at energies lower than peroxide bond dissociation, while protonation of TATP leads to cleavage of the ring structure. These results provide a method for pico-gram detection levels of TATP using commercial instrumentation commonly available in forensic laboratories. As a point of comparison, a detection limit of 15 ng was obtained by flame ionization detection.     

Fast detection of triacetone triperoxide (TATP) from headspace using planar solid-phase microextraction (PSPME) coupled to an IMS detector

Triacetone triperoxide (TATP) is a high explosive synthesized from easily available reactants making it accessible for illicit uses. In this study, fast detection of TATP is achieved using a novel planar solid-phase microextraction (PSPME) as a preconcentration and sampling device for headspace analysis offering improved sensitivity and reduced sampling time over the conventional fiber-based solid-phase microextraction (SPME) when followed by ion mobility spectrometer (IMS) detection. Quantitation and comparison of the retention capabilities of PSPME as compared to the commercially available SPME were determined using TATP standards and analyzed using gas chromatography–mass spectrometry for SPME analysis and a commercial IMS with no instrumental modification for PSPME. Static and dynamic headspace extractions were used and compared for PSPME extractions, in which low milligram quantities of TATP were detected within 30 s of static mode sampling and less than 5 s in the dynamic mode sampling for PSPME–IMS.     

Effects of various fire-extinguishing reagents for thermal hazard of triacetone triperoxide (TATP) by DSC/TG

Acetone, hydrogen peroxide (H₂O₂), and sulfuric acid (H₂SO₄) are easily to produce triacetone triperoxide (TATP), which is an organic peroxide and a hazardous material. The aim of this study was to analyze the thermal hazard of various fire-extinguishing reagents mixed with TATP. Various functions of fire-extinguishing reagents may have different extent of reactions with TATP. Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TG) were used to detect the thermal hazard and to evaluate the effect of fire-extinguishing reagents mixed with TATP under fire condition. TATP decomposed rapidly and final decomposition was calculated before 200 °C. Therefore, heat of decomposition (ΔH _d) of TATP was evaluated to be 2,500 J g^?1 by DSC under 2 °C min^?1 of heating rate. H₂O₂, acetone, and H₂SO₄ should not be mixed in a wastewater drum. TATP decomposed at 50 °C by DSC using O₂ of reaction gas that is an exothermic reaction and can decompose a large amount of heat. Therefore, TATP was applied to assess thermal pyrolysis by DSC employing N₂ of reaction gas that can analyze an endothermic reaction. Mass loss percentage of TATP was evaluated to be 100 % when the ambient temperature exceeds 110 °C by TG using O₂ or N₂ of reaction gas.     

Development of an LC/MS method for the trace analysis of triacetone triperoxide (TATP)

The detection and quantification of triacetone triperoxide (TATP) using LC/MS is investigated. GC/MS analysis of TATP is hindered by stationary phase activation in very short periods of time. Due to the lower temperatures used in LC. this problem is not encountered. This study presents a method that is suitable for the detection of TATP at levels as low as 100 pg microl(-1) (10 ng per 100 microl). Initial findings are also reported for the investigation of a secondary chromatographic peak, which is thought to be caused by separation of two conformers. This study concludes that LC/MS is a suitable technique for the analysis of trace levels of TATP.     

Gas chromatography/time‐of‐flight mass spectrometry of triacetone triperoxide based on femtosecond laser ionization

Triacetone triperoxide (TATP), which is used as an explosive in acts of terrorism, was measured by means of gas chromatography/multiphoton ionization/time‐of‐flight mass spectrometry using a deep‐ultraviolet (deep‐UV) femtosecond laser as an ionization source. The fragmentation process was investigated by changing the intensity of the laser at the center axis of a molecular beam. A molecular ion was observed using a femtosecond laser, and the ratio of the intensities of the molecular and fragment ions decreased as the intensity of the laser increased. These results suggest that TATP can be efficiently ionized using a deep‐UV, ultrashort optical pulse. Furthermore, fragmentation was accelerated by excess energy supplied through higher‐order multiphoton processes under a strong radiation field. The detection limits obtained using the molecular ion and two dominant fragment ions, C₂H₃O⁺ and CH, were determined to be 670, 83 and 150 pg, respectively. Copyright © 2009 John Wiley & Sons, Ltd.     

Electrochemical detection of the explosive, hexamethylene triperoxide diamine (HMTD)

A rapid electrochemical detection scheme for the improvised explosive, hexamethylene triperoxide diamine (HMTD) is demonstrated. This is based on the hydrolysis of HMTD releasing H₂O₂ and the electrochemical redox cycling of Fe^II/IIIEDTA via the following scheme:

Fe^IIIEDTA + e⁻→Fe^IIEDTA     

Selective and rapid determination of biogenic amines by capillary zone electrophoresis

Summary A rapid separation of 21 amines by high-performance capillary zone electrophoresis with indirect photometric detection is presented. The electrolyte is based on copper(II) as primary constituent. Factors affecting the separation by this electrolyte have been investigated and include the composition of the buffer, the voltage, the temperature and the mode of injection. External calibration was used to characterize the analytical response to each amine. The detection limits were approximately 0.05 μg mL⁻¹ for almost all the amines. After electrokinetic or hydrodynamic injection calibration plots of peak area against concentration were linear between 0.05 and 10 μg mL⁻¹. The method has been applied to the analysis of biogenic amines in synthetic samples; the recoveries of the amines from such samples, determined by the standard addition technique, were in the range 90 to 110%.     

Determination of the oxidant activity of chlorinated water by chronoamperometry

A new version of the chronoamperometric method, adapted to the determination of the oxidative (oxidant) activity of a medium on an example of chlorinated water, was proposed. The supporting solution contained K₄Fe(CN)₆. By its oxidation with oxidants present in the sample, K₃Fe(CN)₆ formed; its reduction current served as an analytical signal. The current of K₃Fe(CN)₆ reduction was recorded at a potential of 0 V, selected from the cyclic voltammogram of the K₃Fe(CN)₆/K₄Fe(CN)₆ system in the range where the oxidized form of the reagent was reduced and the reduced form was stable. A gold electrode was the measuring electrode. The possibility of using a stable solution of K₃Fe(CN)₆ as a component of a standard addition and as a solution for plotting a calibration curve was demonstrated. The limit of detection of the amount of dissolved chlorine and products of its interaction with water is 8 × 10^–6 M. The data obtained by the proposed procedure and by the iodometric methods correlate well with each other (r = 0.93–0.95). The proposed version of the chronoamperometric method can be used to monitor the amount of dissolved chlorine and products of its interaction with water in water supply systems, pools, and disinfecting solutions and to determine other water-soluble oxidants.     

Selective detection and identification of phosphorylated proteins by simultaneous ligand-exchange fluorescence detection and mass spectrometry

A ligand-exchange method for the detection and identification of phosphorylated peptides in complex mixtures is presented that is based on the characterization of phosphorylated species by solution-phase interactions with Fe(III) ions and subsequent fluorescence readout. After the separation of the peptides and digest products on a reversed-phase LC column, the flow is split between the two detection systems. One part is directed towards an electrospray mass spectrometer for direct detection and identification of all the peptides present in the sample. The other part of the flow is directed towards a ligand-exchange detection system. This system relies on the specific release of a fluorescent reporter ligand from a Fe(III)-complex in the presence of phosphorylated peptides. To recognize false positive signals due to high-affinity non-phosphorylated high-acidic peptides and other compounds which are known to be a problem in for instance immobilized metal affinity chromatography (IMAC), a second run is performed after incubation of the sample with alkaline phosphatase. A positive signal in this second run indicates a high-affinity non-phosphorylated compound. The method is illustrated using digest from a phosphorylated alpha-casein. Automated switching between MS and MS-MS was performed to obtain additional information about the compounds present in the sample. The linearity of the method was tested in the range of 0.5-80 microM of phosphorylated peptides. A limit of detection (LOD) of 0.5 microM was obtained for a mono-phosphorylated peptide. The interday (n=4) and intraday precision (n=3) expressed as relative standard deviation was better than 10%.