Determination of Triacetone Triperoxide with a N,N-Dimethyl-p-phenylenediamine Sensor on Nafion Using Fe3O4 Magnetic Nanoparticles

Article abstract of DOI:10.1021/acs.analchem.5b01775

The explosive triacetone triperoxide (TATP) can be easily manufactured from readily accessible reagents and is extremely difficult to detect, owing to the lack of UV absorbance, fluorescence, or facile ionization. The developed method is based on the acidic hydrolysis of TATP into H₂O₂, pH adjustment to 3.6, and the addition of magnetite nanoparticles (Fe₃O₄ MNPs) to the medium to produce hydroxyl radicals from H₂O₂, owing to the peroxidase-like activity of MNPs. The formed radicals converted the N,N-dimethyl-p-phenylenediamine (DMPD) probe to the colored DMPD⁺ radical cation, the optical absorbance of which was measured at a wavelength of 554 nm. The molar absorptivity (ε) of the method for TATP was 21.06 × 10³ L mol^-1 cm^-1. The colored DMPD⁺ product in solution could be completely retained on a cation-exchanger Nafion membrane, constituting a colorimetric sensor for TATP and increasing the analytical sensitivity. The proposed method did not respond to a number of hand luggage items like detergent, sweetener, sugar, acetylsalicylic acid (aspirin), and paracetamol-caffeine-based analgesic drugs. On the other hand, TATP could be almost quantitatively recovered from a household detergent and sweetener that can be used as camouflage for the analyte. Neither common soil and groundwater ions (e.g., Ca²⁺, Mg²⁺, K⁺, Cl^-, SO₄^2-, and NO₃^-) at 100-fold ratios nor nitro-explosives of trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and pentaerythritol tetranitrate (PETN) at 10-fold amounts interfered with the proposed assay. The method was statistically validated against the standard GC/MS reference method.

Full text of DOI:10.1021/acs.analchem.5b01775

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Technical Note
Determination of Triacetone Triperoxide (TATP) with
a N,N-dimethyl-p-phenylene diamine (DMPD) Sensor
on Nafion using Fe3O4 Magnetic Nanoparticles
Ziya Can, Ay#em Üzer, Kader Türkekul, Erol Erça#, and Re#at Apak
Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.5b01775 • Publication Date (Web): 10 Sep 2015
Downloaded from http://pubs.acs.org on September 15, 2015
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Analytical Chemistry
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Determination of Triacetone Triperoxide (TATP) with a N,N-
dimethyl-p-phenylene diamine (DMPD) Sensor on Nafion using
Fe3O4 Magnetic Nanoparticles
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Ziya Can, Ayꢀem Üzer, Kader Türkekul, Erol Erçağ, Reꢀat Apak*
Department of Chemistry, Faculty of Engineering, Istanbul University, Avcilar, Istanbul 34320, Turkey
ABSTRACT: The explosive triacetone triperoxide (TATP) can be easily manufactured from readily accessible reagents, and is
extremely difficult to detect, owing to the lack of UV absorbance, fluorescence, or facile ionization. The developed method is
based on the acidic hydrolysis of TATP into H O , pH adjustment to 3.6, and the addition of magnetite nanoparticles (Fe O MNPs)
2
2
3
4
to the medium to produce hydroxyl radicals from H O , owing to the peroxidaseꢁlike activity of MNPs. The formed radicals conꢁ
2
2
+
verted the N,Nꢁdimethylꢁpꢁphenylene diamine (DMPD) probe to the colored DMPD radical cation, the optical absorbance of
which was measured at a wavelength of 554 nm. The molar absorptivity (ε) of the method for TATP was 21.06 x 10 L mol cm .
The colored DMPD product in solution could be completely retained on a cationꢁexchanger Nafion membrane, constituting a colꢁ
3
ꢁ1
ꢁ1
+
orimetric sensor for TATP and increasing the analytical sensitivity. The proposed method did not respond to a number of hand
luggage items like detergent, sweetener, sugar, acetylsalicylic acid (aspirin) and paracetamolꢁcaffeine based analgesic drugs. On the
other hand, TATP could be almost quantitatively recovered from a household detergent and sweetener that can be used as camouꢁ
2+
2+
+
ꢁ
2ꢁ
ꢁ
flage for the analyte. Neither common soil and groundwater ions (e.g., Ca , Mg , K , Cl , SO , and NO ) at 100ꢁfold ratios nor
4
3
nitroꢁexplosives of TNT, RDX, and PETN at 10ꢁfold amounts interfered with the proposed assay. The method was statistically
validated against the standard GCꢁMS reference method.
Introduction
source, and depend on volatile or aerosol type analytes. As a
result, they may not be available in many onꢁsite investigaꢁ
Triacetone triperoxide (TATP) was first discovered and synꢁ
thesized in the 19 century by Wolffenstein . TATP can be
easily manufactured from hydrogen peroxide and acetone
using hydrochloric or sulfuric acid as catalyst . TATP is estiꢁ
mated to be 88% of trinitrotoluene (TNT) blast strength and
classified as a primary explosive . However, TATP is both
sublimable and unstable, and therefore unsuitable for military
and engineering uses . Because of its high blast power and
simple synthesis, this homemade explosive is frequently used
10
th
1
tions . The results from IMS are affected by factors such as
temperature and moisture, whereas fluorescence suffers from
5
2
light scattering from luminophore impurities . For both miliꢁ
tary and improvised explosives, more appropriate devices and
colorimetric methods of onꢁsite analysis measuring liqꢁ
3
11
12,13
uid and air samples
have recently been developed in
4
laboratory scale, but are basically unavailable commercially.
Molecularly imprinted polymerꢁbased electrochemical senꢁ
14
5
5
sors , electrogenerated chemiluminescence (CL) and other
in terrorist actions .
15
16
CL techniques also utilizing nanoparticles have been used
for the determination of TATP. Our research group has colorꢁ
imetrically determined TATP with the aid of a molecular
spectroscopic sensor based on the reaction of H O with cuꢁ
TATP detection by conventional explosive identification
devices or realꢁtime use of canines at hot spots of public safety
control (such as airline terminals) is a challenging task, beꢁ
cause the chemical structure of TATP is devoid of nitroꢁ and
other easily reacting functional groups . TATP neither has a
significant UVꢁVis absorption nor fluorescence emission, and
2
2
17
6
pricꢁneocuproine reagent . In addition to these, microfluidic
paperꢁbased analytical devices (ꢂꢁPADs) for colorimetric
TATP determination in the field have been recently develꢁ
oped, using ammonium titanyl oxalate and acidic KI reaꢁ
7
additionally its (sugarꢁlike) appearance is quite unsuspicious .
In the recent decade, three reviews dealing with the detection
10,18
6
,8,9
gents . For optical (colorimetric or fluorometric) sensing of
of peroxideꢁbased explosives have been published . Several
tandem instrumental techniques involving spectroscopy have
been used to detect peroxideꢁbased explosives. Methods based
on MS are very sensitive and can detect trace amounts of
explosives, but instruments are expensive and often not suitaꢁ
ble for onꢁsite testing. Ion mobility spectrometry (IMS), Fouꢁ
rier transform infrared spectroscopy (FTIR), and Raman specꢁ
troscopy are some of the instrumental analytical methods that
have been used onꢁsite for explosive residues detection, but
their field use has certain limitations, because they are costly,
bulky, require an easily consumable battery pack as power
the hydrogen peroxide obtained from peroxide explosives,
some researchers have focused on peroxidaseꢁbased methods,
which are known to be prone to various interferences and
poisoning of enzymes by false substrates added to biocataꢁ
19
lysts . Thus, a combination of nanomaterialꢁbased degradaꢁ
tion and optical sensing of peroxide explosives is believed to
enable fieldꢁapplicable development of simple, low cost and
sensitive methods of determination. Firstly, Goa et al. reported
that Fe O nanoparticles have an intrinsic peroxidaseꢁlike
3
4
activity widely used in oxidative conversions of environmental
20
treatment or analytical detection . After this report, several
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Page 2 of 6
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9,21,22
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colorimetric
and fluorometric methods were developed
Preparation of Solutions
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for hydrogen peroxide determination and Fe O MNPs were
ꢁ1
3
4
The working solutions of TATP at 10ꢁ100 mg L were preꢁ
2
4,25
ꢁ1
used for removing organic pollutants . Peroxidaseꢁlike
activity of Fe O MNPs stems from its structural similarity to
pared from corresponding stock solutions of 500 mg L conꢁ
3
4
centration in acetone. HCl solution (4 M), NaOH solutions (2
M and 4 M), pH 3.6 acetic acid buffer (containing a total
CH COOH/CH COONa concentration of 2 M), Fe O MNPs
2
+
3+
20
the Fenton’s reagent (Fe /Fe ions in solution) . In this
regard, it was aimed to perform acid hydrolysis on TATP,
3
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3
4
ꢁ
1
ꢁ3
3
degrade the liberated hydrogen peroxide with the use of Fe O4
(100 mg L ), and DMPD (5 x 10 M) were prepared in water
and stored at room temperature before use.
MNPs as catalysts, and finally produce the colored pꢁquinoneꢁ
+
imine oxidation products (DMPD radical) with a pꢁ
Synthesis
phenylenediamineꢁbased (DMPD) reagent, thereby enabling
their spectrophotometric determination, and to develop a relatꢁ
ed molecular spectroscopic sensor for the rapid, selective, and
sensitive assay of TATP onꢁsite. Also, a colorimetric sensor
designed in our laboratories for antioxidant and prooxidant
compounds has been simultaneously developed for hydrogen
For synthesis of TATP and Fe O MNPs, literature methods
were applied directly (for details of synthesis, see Supportꢁ
ing Information).
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2,19
Recommended Procedure for TATP Determination
TATP assay consisted of three parts, namely, acidic hydrolꢁ
ysis of TATP into hydrogen peroxide, oxidative degradation
of the H O product with the aid of Fe O MNPs, and spectroꢁ
26
peroxide sensing . The devised method was favorably applied
to complex samples containing nitroꢁenergetic materials (such
as TNT, hexahydroꢁ1,3,5ꢁtrinitroꢁ1,3,5ꢁtriazine (RDX) and
pentaerythritol tetranitrate (PETN)), detergents bearing perꢁ
carbonateꢁ and perborateꢁbased bleaching agents, analgesic
drugs having acetylsalicylate, paracetamol and caffeine ingreꢁ
dients, and finally sugar and synthetic sweeteners. Common
ions present in soil extracts were also shown not to interfere,
as demonstrated by using loamy clay soil as analyte matrix.
2
2
3
4
+
photometric determination of the oxidized DMPD cation.
Acidic hydrolysis of TATP: A volume of 2 mL of 4 M HCl
ꢁ
1
was added to 1 mL of TATP solution at 10ꢁ100 mg L conꢁ
centration, and allowed to stand for 5 min for H O formation.
2
2
The sample was neutralized with 2 mL of 4 M NaOH, and
adjusted to pH 3.6 with 2 mL of acetic acid buffer solution.
Degradation of H O and Oxidation of DMPD to the Colꢁ
ored Cationic Product: After adjustment of pH, 2 mL of 100
mg L Fe O MNPs were added to the solution for degradaꢁ
tion of the liberated H O to reactive oxygen species (ROS,
essentially comprised of hydroxyl and perhydroxyl radicals).
Finally 1 mL of 5x10 M DMPD was added, where DMPD
was oxidized to the colored DMPD cationic radical. After 30
min, the tubes were centrifuged at 5000 rpm for 5 min and the
absorbance of the final solution at 554 nm was read against a
reagent blank. For measurement on a Nafion membrane, the
membrane was sliced into 4.5 x 0.5 cm pieces, and was imꢁ
mersed in a sample tube after adding DMPD to the sample
solution. The tube was placed in a rotator and agitated for 30
min so as to enable color development on the membrane surꢁ
face. After 30 min, the colored membrane was placed in a 1
2
2
Experimental
Safety Note
ꢁ1
3
4
TATP is an extremely dangerous material, which may lead
to explosions under impact, friction, and temperature changes.
Its synthesis may only be carried out by highly qualified perꢁ
sonnel, and at small quantities not exceeding 100 mg (as highꢁ
2 2
ꢁ3
+
2
7
er amounts may cause spontaneous explosions) .
Instrumentation and Chemicals
All reagents were of analytical reagent grade unless otherꢁ
wise stated. DMPD (suitable for peroxidase test) and Nafion
1
15 perfluorinated membrane were purchased from Sigmaꢁ
Aldrich and all other reagents from Merck and SigmaꢁAldrich.
The TATPꢁspiked standard loamy clay soil (51.9% sand, 28.2
clay, and 19.9% soil dust) for recovery studies was kindly
provided by the Forestry Faculty of Istanbul University. As
percarbonate is known to release hydrogen peroxide and sodiꢁ
um carbonate upon hydrolysis, a household detergent containꢁ
ing sodium percarbonate was studied for interference testing.
In addition, the handꢁluggage items of aspartameꢁbased sweetꢁ
ener (CANDEREL), acetylsalicylic acid, paracetamolꢁcaffeine
based analgesic drugs and sugars having similar color and
appearance to that of TATP were studied as possible interꢁ
ferents. TNT, RDX and PETN were kindly provided by the
Mechanical and Chemical Industry Corporation (MKEK) of
Turkey.
mm optical cuvette containing H O (to prevent sticking of
membrane to the walls of the cuvette), and its absorbance at
50 nm was read against a blank membrane prepared under
2
5
identical conditions.
The scheme for the method is summarized as: Add 1 mL of
TATP solution + 2 mL of 4 M HCl (allow to stand for 5 min
for hydrolysis into H O ) + 2 mL of 4 M NaOH + 2 mL of pH
2
2
ꢁ1
ꢁ3
3
.6 buffer + 2 mL 100 mg L Fe O MNPs + 1 mL of 5x10
3 4
M DMPD in this order. In the application of the solution and
membrane sensing methods, measure A554 and A550, respecꢁ
tively, against a reagent blank after 30 min of DMPD addition
Studies concerning method optimization are given in the
Supporting Information. For optimization of pH, DMPD conꢁ
centration, Fe O MNPs concentration and reaction time, see
(
The spectra and absorption measurements were recorded in
matched Hellma quartz cuvettes using a Varian CARY Bio
3
4
Figures Sꢁ1, Sꢁ2, Sꢁ3 and Sꢁ4, respectively.)
Determination of TATP in Complex Materials
1
00 UVꢁvis spectrophotometer. The optical thickness of the
cuvettes was 1 cm for solution phase, and 1 mm for Nafion
membrane measurements. The proposed method for TATP
assay was validated against GCꢁMS utilizing a Thermo Scienꢁ
tific Trace gas chromatograph coupled with a DSQII mass
spectrometer containing electron impact ionization and quadꢁ
rupole analyzer. SEM images of Fe O MNPs were recorded
For interference tests, the recovery of TATP was studied in
mixtures of nitroꢁexplosives (RDX, TNT and PETN), in synꢁ
thetic solutions containing common soil ions, in spiked houseꢁ
hold detergent and sweetener, and in artificially contaminated
clay soil (for details of methods, see Supporting Information).
3
4
with the aid of FEI Model Quanta 450 FEG scanning electron
microscope.
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Analytical Chemistry
Statistical Analysis
Descriptive statistical analyses were carried out by Miꢁ
Analytical Figures of Merit
1
2
The proposed assay was applied to the determination of
pure H O without any acidic hydrolysis and neutralization
crosoft Office 2013, covering the calculation of the population
means together with their corresponding standard errors using
Excel software. Results were expressed with acceptable preciꢁ
sion as {mean ± standard deviation (SD)}. As a measure of
accuracy and precision, Student (tꢁ) and Fꢁtests, respectively,
were used for validating the proposed method against GC/MS
determination of TATP.
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prior to measurement (i.e. 4 mL of water was added instead of
the solutions used in the recommended procedure), yielding
the calibration line equation:
A554 nm = 5426 CH2O2 + 0.0334 (r = 0.9990) … (Eq. 1)
ꢁ1
where CH2O2 is the H O concentration (in mol L ) in final
2
2
3
ꢁ1
solution and the molar absorptivity is: ε = 5.43 x 10 L mol
ꢁ1
Results and Discussion
cm .
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Analyte, catalyst and method
TATP solutions at final concentrations ranging between 1
ꢁ1
Mass spectrum of synthesized TATP was checked with the
aid of GCꢁMS, and the characteristic ions generated by the
analyte (m/z values of 43, 58, 75, 101 and 117) were observed.
For synthesized TATP, compatible results were achieved from
and 10 mg L gave a linear calibration curve:
ꢁ
2
ꢁ2
A554 nm = (9.48±0.48)x10 C
(r = 0.9993) ... (Eq. 2)
+ (7.40±2.93)x10
TATP
28
where the molar absorptivity for TATP was
ε =
both GCꢁMS library and literature .
3
ꢁ1
ꢁ1
(21.06±1.07) x 10 L mol cm (the optical thickness of the
cuvettes was 1 cm for the solution phase measurements), with
On the other hand, the size and shape of Fe O MNPs were
3
4
determined by SEM. It was demonstrated that the particles
appear spherical with diameter range between 20ꢁ30 nm (see
Figure Sꢁ5). Since Fe O MNPs with smaller sizes are reported
ꢁ1
a limit of detection (LOD) = 0.47 mg L and limit of quantifiꢁ
cation (LOQ) = 1.57 mg L (LOD = 3σ /m and LOQ =
ꢁ1
bl
3
4
1
0σ /m, where σ denotes the standard deviation of a blank
bl bl
to show higher catalytic activity, this property is indicative of
2
0
and m is the slope of calibration curve). The visible spectra of
good catalytic ability . In order to determine the magnetic
properties of nanoparticles that can potentially be used for
magnetic field guided targeting, Fe O MNPs were dispersed
+
DMPD cation (obtained from oxidation of DMPD with ROS
catalytically generated from hydrolyzed TATP solutions) are
shown in Fig. 1.
3
4
in water. After that, a magnet was applied near the tube to
separate the nanoparticles by collecting them on one side of
the tube wall. The developed method is based on the acidic
hydrolysis of TATP into H O , followed by pH adjustment to
2
2
3
.6, and addition of Fe O4 MNPs (having peroxidaseꢁlike
3
activity) to this medium to produce ROS (i.e. hydroxyl and
2
5
perhydroxyl radicals) from H O . Finally the produced ROS
2
2
+
oxidize DMPD to the colored DMPD radical cation, enabling
spectrophotometric measurement of this colored product either
in solution or on a Nafion membrane, the latter with higher
sensitivity (Scheme 1).
+
Figure 1. The visible spectra of DMPD cation (obtained from
oxidation of DMPD with ROS catalytically generated from hydroꢁ
ꢁ
1
ꢁ1
ꢁ1
lyzed TATP solutions) at (1) 1 mg L (2) 2 mg L (3) 4 mg L
ꢁ
1
ꢁ1
ꢁ1
(
4) 6 mg L (5) 8 mg L (6) 10 mg L final concentrations.
Fig. 2 compares the absorption spectra of the DMPDꢁ
TATPꢁFe O MNPs system and DMPDꢁTATP system (for 40
3
4
ꢁ
1
mg L TATP). It was observed that the H O intrinsically
2
2
derived from TATP could oxidize DMPD to a certain extent
(spectrum 1 in Fig 2) which would be expected to be advantaꢁ
geous for direct detection of TATP residues in sites of crimiꢁ
nologic investigation, but this oxidation could be significantly
enhanced in the presence of Fe O MNPs (spectrum 2 in Fig
3
4
2
), due to the peroxidaseꢁlike activity of these nanoparticles.
The two spectra shown in Fig. 2 have similar characteristics,
confirming that the identity of the chromophore in both cases
+
was the DMPD cation, but nanoparticles caused a strongly
+
increased signal. Although the colored DMPD radical exhibꢁ
ited two absorption maxima at the wavelengths of 554 nm and
15 nm, the higher wavelength maximum at 554 nm was used
for all subsequent measurements because of its strength ,
distinctive character and possibly less interference from natuꢁ
ral substances found in soil (such as plant pigments and humic
acids) which may absorb light at close wavelengths.
5
21
Scheme 1. Schematic presentation of H O formation upon
2
2
+
TATP hydrolysis, catalytic ROS generation, and DMPD
radical cation formation as the basis of indirect spectro-
photometric determination of TATP.
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Figure 2. Visible absorption spectra of the solutions from the (1)
DMPDꢁTATP, (2) DMPDꢁTATPꢁFe O MNPs systems.
3
4
For each concentration, three replicate readings were made,
and the relative standard deviation (RSD) of a given set of
readings varied in the range of 2.53ꢁ6.67%, depending on
TATP concentration. On the other hand, the same TATP soluꢁ
tions gave the calibration curve (Eq. 3) when the measureꢁ
ments were carried out on a Nafion membrane:
Figure 3. (a) Original Nafion membrane slice, (b) Reference
membrane (including all reagents, without TATP), (c) Nafion
ꢁ1
membrane – as in (b) – in the presence of TATP at 20 mg L
concentration after hydrolysis to H O , (d) Nafion membrane – as
2
2
ꢁ
1
in (b) – in the presence of TATP at 60 mg L concentration after
hydrolysis to H O , and (e) Nafion membrane – as in (b) – in the
2
2
ꢁ
1
ꢁ
2
ꢁ2
presence of TATP at 100 mg L concentration after hydrolysis to
A550 nm = (6.82±0.42)x10 CTATP+ (1.08±2.56)x10
ꢁ
1
H O .
2 2
(CTATP : mg L concn.; r=0.9990) ...(Eq. 3)
Household detergent and sweetener can be used as camouꢁ
where the molar absorptivity for TATP on Nafion memꢁ
4
ꢁ1
ꢁ1
flage material for TATP because of the color and appearance
similarities to TATP. For this reason, they were studied as
possible sources of interference. When the detergent was
dissolved in water, it yielded a mixture of hydrogen peroxide
brane surface was ε = (15.15±0.09)x10 L mol cm (the
optical thickness of the cuvettes was 0.1 cm for Nafion memꢁ
brane measurements), with a limit of detection (LOD) = 0.1
ꢁ
1
ꢁ1
mg L and limit of quantification (LOQ) = 0.33 mg L , RSD
varying between 2.61ꢁ8.39%, depending on the concentration.
The improvement in sensitivity of the sensorꢁbased method (as
reflected in lower detection and quantification limits compared
to the solutionꢁbased method) most probably arose from the
lower intercept value of Eq. 3 than of Eq. 2, because all the
colored product formed in solution was homogenously colꢁ
lected on the Nafion membrane (Fig. 3). This also increased
the apparent molar absorptivity approximately by an order of
magnitude.
(
which eventually decomposed to water and oxygen) and
29
sodium carbonate . The resulting hydrogen peroxide was a
potential interference for the proposed assay. For eliminating
this effect, we used solubility differences between the analyte
and detergent. After selective acetone extraction of TATP
from detergent or sweetener mixture, the proposed assay was
applied. TATP recoveries from detergentꢁadded sample using
the solution‒ and membrane‒based methods were 93 and
109%, and from sweetenerꢁadded sample 90 and 97%, respecꢁ
tively. Additionally, the proposed method was directly applied
to detergent, sweetener, sugar, acetylsalicylic acid and paraceꢁ
tamolꢁcaffeine. The bar diagram (Fig. 4) shows that these
camouflage materials carried by passengers as personal beꢁ
longings in handꢁheld luggages had no significant responses.
The coefficients of variation (CVs) of intraꢁassay measureꢁ
ments for TATP in the solution‒ and membrane‒based deterꢁ
minations were 1.75% and 5.07%, whereas those of interꢁ
assay measurements were 2.31% and 5.84%, respectively
(N=5), showing that sensor measurements enabled higher
precision.
0
.5
The physical appearance of Nafion membranes (before and
after treatment of TATP samples at different concentrations
following hydrolysis to H O ) can be seen in Fig. 3, where the
0.3
0.1
2
2
original membrane turned pinkꢁorange colored when loaded
with DMPD, and membrane color varied from light pinkꢁred
to dark pinkꢁred in the presence of H O formed from different
2
2
concentrations of TATP.
Recovery and interferences
1
2
3
4
5
6
-0.1
The percentage recoveries of TATP from a nitroꢁexplosive
mixture are shown in Table Sꢁ1. The recoveries were suffiꢁ
cient for the tested measurement media, both in solution (94ꢁ
Solution
Nafion Membrane
ꢁ1
Figure 4. Responses of (1) 40 mg L TATP, (2) Acetylsalicylꢁ
ic acid, (3) ParacetamolꢁCaffeine, (4) Household Detergent,
1
05%) and on the Nafion membrane (96ꢁ101%). The results
showed the nonꢁinterference of nitroꢁexplosives, i.e. TNT,
RDX and PETN, to the proposed method.
(5) Sweetener, (6) Sugar.
Reusability of membranes
Common ions abundantly found in soil and groundwater
+
2+
2+
ꢁ
ꢁ,
2ꢁ
4
(
K , Mg , Ca , Cl , NO SO ) at 100ꢁfold concentration of
TATP determinations were repeated five times with the use
of the same membrane to examine the reusability of Nafion.
3
TATP did not affect the recoveries in both solution (96ꢁ104%)
and Nafion membrane applications (97ꢁ108%).
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Analytical Chemistry
After each experiment, the Nafion membrane was immersed
SUPPORTING INFORMATION AVAILABLE
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in 1 M HNO solution for 2 min, then washed thoroughly with
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Additional information as noted in text. This information is availꢁ
able free of charge via the Internet at http://pubs.acs.org/.
deionized water before next use. The relative standard deviaꢁ
tion of measurements was 7.07%.
Method validation against GCꢁMS Determination of TATP
REFERENCES
ꢁ1
TATP working solutions in acetone at 1ꢁ10 mg L concenꢁ
(1) Wolffenstein, R. Berichte der deutschen chemischen
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trations were analyzed with GCꢁMS, and the mean value of
three repetitive injections was used for each calculation. The
calibration equation between peak area (A) and concentration
was:
1
159.
3) Marshall, M.; Oxley, J. C. In Aspects of Explosives Detection,
Oxley, M. M. C., Ed.; Elsevier: Amsterdam, 2009, pp 11ꢁ26.
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(
0
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0
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4
A = 4.17x10 C
ꢁ1.10x10 (r = 0.9998)
TATP
(
The results of measurements carried out in solution and on
Nafion membrane were validated against the reference GCꢁ
1
83ꢁ188.
28
(5) Parajuli, S.; Miao, W. J. Anal. Chem. 2013, 85, 8008ꢁ8015.
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MS procedure using TATPꢁcontaminated soil samples. For
ꢁ1
the recovery of TATP from 5 mg L solutions on N=5 repetiꢁ
3
tive determinations, the proposed and reference methods esꢁ
sentially showed no significant differences between the preciꢁ
sion and accuracy of results (see Supporting Information,
Table Sꢁ2). The tꢁ (Student) and Fꢁtests were used for comparꢁ
(
7) Kende, A.; Lebics, F.; Eke, Z.; Torkos, K. Microchimica Acta
2
008, 163, 335ꢁ338.
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ing the population means and variances, respectively . The
confidence level used in validation of solution phase findings
was 95% for both tꢁ and Fꢁ tests, whereas the corresponding
levels in Nafion membrane measurements were 95% and 99%,
respectively, for tꢁ and Fꢁtests (Table Sꢁ2).
(
(
Leibovich, R.; Pevzner, A.; Krivitsky, V.; Davivi, G.; Presman, I.;
Elnathan, R.; Engel, Y.; Flaxer, E.; Patolsky, F. Nat. Commun. 2014,
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Conclusions
(
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13) Lin, H. W.; Suslick, K. S. J. Am. Chem. Soc. 2010, 132,
There are a great many complex techniques for TATP analꢁ
ysis in the literature, but methods for field analysis are limited.
Some of these methods are patented and some require highꢁ
cost and easily inhibited peroxidase enzymes. Alternatively, a
novel colorimetric method using Fe O MNPs has been develꢁ
(
1
5519ꢁ15521.
(14) Mamo, S. K.; GonzalezꢁRodriguez, J. SensorsꢁBasel 2014, 14,
23269ꢁ23282.
(15) Girotti, S.; Ferri, E.; Maiolini, E.; Bolelli, L.; D'Elia, M.;
Coppe, D.; Romolo, F. S. Anal.&Bioanal. Chem. 2011, 400, 313ꢁ320.
3
4
oped and converted into a sensor on a Nafion membrane. The
method has high selectivity over possible interferents existing
in nitroꢁexplosive residues, household detergents, reducing
sugars, acetylsalicylic acid, paracetamolꢁcaffeine and soil
extracts. Both the Nafion membrane and Fe O MNPs are
(
(
16) Li, X. H.; Zhang, Z. J.; Tao, L. Analyst 2013, 138, 1596ꢁ1600.
17) Eren, S.; Uzer, A.; Can, Z.; Kapudan, T.; Ercag, E.; Apak, R.
Analyst 2010, 135, 2085ꢁ2091
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L. C. Anal MethodsꢁUk 2014, 6, 2047ꢁ2052.
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reusable; additionally, unlike peroxidase, MNPs can be magꢁ
netically separated from the medium to stop the reaction at any
desired point. Because of these advantages, the developed
method has a low cost per analysis, enabling the screening of
large numbers of samples in the field. In addition, the achieved
LOD values for the proposed method are very suitable for
field use and results validated against GCꢁMS. The combined
use of magnetite NPs and DMPD membrane sensor enables
the development of a precise, sensitive and selective method
for TATP assay, which is suitable for both automated and onꢁ
site analysis. This membrane sensor increased sensitivity and
precision with respect to solutionꢁbased measurements, and is
believed to find potential use in antiꢁterror activities for public
security.
(
19) Wei, H.; Wang, E. Anal. Chem. 2008, 80, 2250ꢁ2254.
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Wang, T.; Feng, J.; Yang, D.; Perrett, S.; Yan, X. Nature
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Tang, H. Q. Microchim. Acta 2009, 165, 299ꢁ305.
(
22) Zhuang, J.; Zhang, J. B.; Gao, L. Z.; Zhang, Y.; Gu, N.; Feng,
J.; Yang, D. L.; Yan, X. Y. Materials Letters 2008, 62, 3972ꢁ3974.
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(
Talanta 2011, 85, 1075ꢁ1080.
(24) Wang, N.; Zhu, L.; Wang, D.; Wang, M.; Lin, Z.; Tang, H.
Ultrasonics sonochemistry 2010, 17, 526ꢁ533.
(25) Zhang, S.; Zhao, X.; Niu, H.; Shi, Y.; Cai, Y.; Jiang, G.
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(
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AUTHOR INFORMATION
Corresponding Author
(
28) Rasanen, R. M.; Nousiainen, M.; Perakorpi, K.; Sillanpaa, M.;
Polari, L.; Anttalainen, O.; Utriainen, M. Anal. Chim. Acta 2008, 623,
9ꢁ65.
29) In Applications of Hydrogen Peroxide and Derivatives, Jones,
* Fax: +90 212 4737180. Eꢁmail: rapak@istanbul.edu.tr
5
ACKNOWLEDGMENT
(
The authors wish to express their gratitude to the Ministry of
National Defence, Office of Technical Services, and to the
Mechanical & Chemical Industry Corporation (MKEK) for the
donation of nitroꢁ and composite explosive samples. Additionally,
the authors thank TUBITAK (Turkish Scientific and Technical
Research Council) for the research project 114Z131.
C. W.; Clark, J. H., Eds.; The Royal Society of Chemistry, 1999, pp
37ꢁ78.
(30) Miller, J. C. J. C.; Miller, J. N. J. N. Statistics for analytical
chemistry, 3rd ed ed.; Ellis Horwood PTR Prentice Hall, 1993.
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