Accepted Manuscript The chemiluminescence determination of 2-chloroethyl ethyl sulphide using luminol– AgNO3 –silver nanoparticls system Bozorgmehr Maddah, Javad Shamsi, Mehran Jam Barsang, Mehdi RahimiNasrabadi PII: DOI: Reference:
S1386-1425(15)00161-4 http://dx.doi.org/10.1016/j.saa.2015.02.009 SAA 13299
To appear in:
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Received Date: Revised Date: Accepted Date:
11 November 2014 29 January 2015 4 February 2015
Please cite this article as: B. Maddah, J. Shamsi, M. Jam Barsang, M. Rahimi-Nasrabadi, The chemiluminescence determination of 2-chloroethyl ethyl sulphide using luminol– AgNO3 –silver nanoparticls system, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2015), doi: http://dx.doi.org/10.1016/j.saa.2015.02.009
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
The chemiluminescence determination of 2-chloroethyl ethyl sulphide using luminol–
2
AgNO3–silver nanoparticls system
3
Bozorgmehr Maddah, Javad Shamsi, Mehran Jam Barsang and Mehdi Rahimi-Nasrabadi*
4
Nanoscience Center, Imam Hossein University, Tehran, Iran
5 6
*
1
Corresponding author. Tel.: +98-2177594707; [email protected] (M. Rahimi-Nasrabadi)
Fax:
+98-2177594707;
Email:
7
Abstract:
8
A highly sensitive chemiluminescence (CL) method for the determination of 2-chloroethyl ethyl
9
sulphide (2-CEES) was presented. It was found that 2-chloroethyl ethyl sulphide (2-CEES) could
10
inhibit the CL of the luminol-AgNO3 system in the presence of silver nanoparticles in alkaline
11
solution, which made it applicable for determination of 2-CEES. The presented method is
12
simple, convenient, rapid and sensitive. Under the optimized conditions, the calibration curve
13
was linear in the range of 0.0001-1 ng mL-1, with the correlation coefficient of 0.992; while the
14
limit of detection (LOD), based on signal-to-noise ratio (S/N) of 3, was 6×10-6 ng mL-1. Also, the
15
relative standard deviation (RSD, n=5) for determination of 2-CEES (0.50 ng mL-1) was 3.1%.
16
The method was successfully applied for the determination of 2-CEES in environmental aqueous
17
samples.
18 19
Keywords: Chemical warfare agent (CWA); 2-Chloroethyl ethyl sulfide; Chemiluminescence; Ag
20
NPs; AgNO3; luminal
21 22
Introduction
23
In recent years, extremely sensitive analytical techniques based on chemiluminescence
24
(CL) and bioluminescence systems have received considerable attention. Simplicity of detection,
25
low limit of detection, large calibration ranges and short analysis times are some of the
26
characteristics that make the methods attractive. Since it was first reported by Albrecht [1] in
27
1928, the CL resulting from the reaction of luminol (5-amino-2,3-dihydrophthalzine-1,4-dione)
28
and an oxidant (H2O2 in particular), in a strongly basic medium, has been extensively studied [2]
29
and applied to the determination of several inorganic species [3].
2
30
In recent years, many attentions have been paid to use metal nanoparticles (MNPs) as
31
nanocatalysts in CL reactions [4-7], because of their unique physical and chemical properties and
32
great analytical potential [8-18]. Cui et al. found that the gold [19], platinum [20] and silver [21]
33
NPs could catalyze and enhance luminol–AgNO3 CL reaction. Sun and Xia [22] also found that
34
Ag NPs exhibited a better CL catalytic ability than gold and platinum NPs. AgNO3 in presence
35
of silver can oxidize water; producing hydroxyl radicals, more easily than gold, since its
36
oxidation potential is lower than that of gold.
37
2-CEES (C4H9ClS) is the stimulants of sulfur mustard and it is important to develop the
38
detectors to detect CWA like sulfur mustard [23]. 2-CEES contains a single chlorine atom on the
39
carbon relative to the sulfur atom (mustard is 2,2-dichlorodiethyl sulfide) [24]. The 2-CEES
40
molecule is much less toxic. Thus, it is expected that 2-CEES closely mimics the reactivity of
41
mustard gas [25]. Other studies have reported various principles and devices for the detection of
42
CWA and stimulants, such as piezoelectric quartz crystal microbalance (QCM), sensors,
43
spectroscopic and chromatographic-based techniques [30-32], including ion mobility mass
44
spectrometry [33,34], enzyme-based [35] and surface acoustic wave (SAW) sensors [36,37].
45
According to the available literature and to the best of our knowledge, no report is available
46
so far for the sensing of 2-CEES based on CL method. In this work, the effect of Ag NPs on the
47
luminol-AgNO3 system was investigated. It was found that Ag NPs could act as a nanocatalyst
48
on the luminol-AgNO3 system to generate CL. Based on the catalytic effect of Ag NPs, a new,
49
rapid, simple, sensitive and inexpensive method was presented for the determination of 2-CEES.
50 51
Experimental
52
Materials
3
53
Silver
nitrate
(AgNO3),
sodium
borohydride
(NaBH4),
trisodium
citrate
54
(C6H5Na3O7·2H2O), sodium hydroxide (NaOH) were purchased from Merck (Darmstadt,
55
Germany). Luminol was purchased from Fluka Corporation (Buchs, Switzerland). All reagents
56
were analytical grade and used without further purification.
57
A 1.77 mg mL-1 stock solution of luminol (3-aminophthalhydrazide) was prepared by
58
dissolving luminol in 0.004 mg mL-1 NaOH. Working solutions of luminol were prepared by
59
diluting the stock solution with appropriate amounts of NaOH solution. Doubly distilled water
60
was used throughout.
61 62
Apparatus
63
The CL intensity was measured and recorded with a Berthold (USA) Luminometer. CL
64
intensity was recorded as a function of time, the time resolution of the apparatus was 0.5 second.
65
UV–visible adsorption spectra were recorded on a Hitachi U-3900H UV–Vis Spectrophotometer
66
(Tokyo, Japan) with 1 cm quartz cells at room temperature. Determining the particle size
67
distribution of the sample suspended in distilled water was performed by dynamic light
68
scattering (DLS) using Malvern instrument (England). TEM image was obtained using a
69
transmission electron microscope (Ziess- EM900). Prior to the measurement, the sample was
70
treated with coating on the Cu-carbon coated grid.
71 72
Preparation of Silver NPs
73
Ag NPs (~5 nm in diameter) were synthesized by the reduction of AgNO3 with NaBH4
74
and stabilized using tri sodium citrate (Na3C6 H5O7) according to the literature [38]. 100 mL of a
75
solution containing AgNO3 and Na3C6 H5O7, both in a concentration of 0.25 mM, was prepared
4
76
and stirred for 30 S. Then, 3 mL solution of NaBH4 (0.037 mg mL-1, freshly prepared) was added
77
quickly to the mixture. The solution immediately turned to yellow and was stirred for 60 S and
78
then stored in refrigerator at 4 °C before use. Ag NPS were characterized by UV-vis
79
spectrophotometer and the surface Plasmon resonance band of silver nanoparticles appears at
80
400 nm (Fig. 1). Furthermore, the prepared Ag NPs were characterized by TEM for definition of
81
its morphology; the TEM image confirms that synthesized Ag NPs have an average size about 5
82
nm (Fig. 2). Meanwhile, particle size distribution of Ag NPs was obtained as shown in Fig. 3. As
83
could be seen, this figure confirms the TEM data (Fig. 2) and most frequency numbers are
84
corresponding to the particles with size of 5 nm.
85 86
CL Measurement
87
100 µL of phosphate buffer and 100 µL Ag NPs solution with certain size was injected
88
into a 40×14-mm quartz tube (used as CL detector). Then, 0.5 mL 1.77 mg mL-1 luminol
89
solution was mixed with 0.5 mL 16.9 µg mL-1 AgNO3 solution and 200 µL of luminol-AgNO3
90
mixture were injected into the quartz tube. The CL signal was measured and recorded with the
91
Luminometer. To optimize the reaction conditions, the concentration of each reactant was varied
92
whilst holding the others constant. Ultimately, the CL intensity as a function of time was
93
recorded in the presence of various trace amounts of 2-CEES. Inhibition in CL intensity in the
94
presence of trace 2-CEES material was considered as an analytical signal.
95 96 97
5
98
Results and discussion
99 100
Inhibition of the Ag NPs-catalysed luminol–AgNO3 reaction by 2-CEES
101
The effect of 2-CEES on the luminol CL reaction catalyzed by Ag NPs was studied using
102
the static injection analysis process. As illustrated in Fig. 4 the CL intensity of luminol-AgNo3
103
reaction was significantly enhanced in the presence of Ag NPs. Interestingly, the CL intensity of
104
luminol-AgNO3 system (catalyzed by Ag NPs) was significantly decreased by addition of 2-
105
CEES. Results revealed that the extent of inhibition is related to the concentration of 2-CEES in
106
the sample. According to the results obtained by Sheng et al [39] it can be deduced that the
107
decreasing of CL intensity can be attributed to high affinity 2-CEES to silver NPs. The sulfur
108
atoms can interaction with Ag NPs and its catalystic feature as luminescence decreased in
109
various concentration with comparison to the luminescence while 2-CEES has not presented.
110
The mechanism of chemiluminescence is based on the oxidation of luminol with AgNO3
111
in alkaline solution. When the silver nanoparticles (NPs) were added to the solution the CL
112
remarkably enhanced. The silver nanoparticles may catalyze the reduction of AgNO3 by luminol.
113
The product luminol radicals reacted with the dissolved oxygen, to produce a strong CL
114
emission. As a result, the CL intensity was substantially increased. While by addition of 2-CEES
115
to the solution containing the luminol-AgNO3-Ag NPs, the 2-CEES adsorbed by the Ag NPs and
116
its catalyzing effect was reduced and resulted to quenching of CL (Fig. 5).
117 118 119
Optimization conditions of CL reaction
120
In order to achieve the highest sensitivity, the reaction conditions of the Ag NPs-
121
catalyzed luminol-AgNO3 system, such as pH, AgNO3, luminol and Ag NPs concentration were 6
122
investigated. The influence of pH on the CL was examined in the range of 9.0-13.0 (Fig. 6A).
123
The highest CL intensity was obtained at pH 12.0. Therefore, pH was adjusted at 12 using
124
phosphate buffer for the subsequent experiments. Results indicated that at the pH higher than
125
12.0, the CL intensity decreases with increasing pH. The effect of AgNO3 concentration on the
126
CL was studied in the range of 0.21 – 8.49 µg mL-1. As shown in Fig. 6B, the CL intensity
127
increased with increasing AgNO3 concentration up to 1.69 µg mL-1 and decrease in the more
128
AgNO3 concentration. The luminol concentration was varied in the range 0.17-1.77 mg mL-1.
129
The CL signal increases linearly with the increasing luminol concentration up to 1.77 mg mL-1.
130
Since the CL signal at luminol concentration of 1.77 mg mL-1 was reached to the highest
131
detectable level of the luminometer; hence, 1.77 mg mL-1 of luminol concentration was used for
132
further experiments (Fig. 6C). Finally, the influence of the concentration of Ag NPs was also
133
investigated (Fig. 6D). As can be seen, the CL intensity increased significantly with the
134
concentration of Ag NPs. The CL signal was reached to the highest detectable level of the
135
luminometer in 100 µL of Ag NPs volume; hence, 100 µL was selected for next experiments. As
136
a result, the optimized conditions for the luminol-AgNO3-silver colloids CL system were as
137
follows: 1.77 mg mL-1 luminol in pH 12.0, 1.69 µg mL-1 and 100 µL of Ag NPs.
138 139
Analytical features of method
140
Calibration curve (i.e., the CL intensity as function of 2-CEES) was obtained by
141
analyzing standard solutions containing different concentrations of the 2-CEES under the
142
optimized experimental conditions. Calibration curve (Fig. 7) was linear in the range of 0.0001-1
143
ng mL-1 with a regression equation of y=11.75x+309.30 (x, ng mL-1; R2 =0.992). The limit of
7
144
detection (LOD), based on signal-to-noise ratio (S/N) of 3, was 6×10-6 ng mL -1. The relative
145
standard deviation (RSD, n=5) for determination of 2-CEES (0.50 ng mL-1) was 3.1%.
146 147
Application of the procedure to real aqueous sample analysis
148
River water sample was collected in 1 L amber glass bottles (without any further
149
treatment), and cooled in refrigerator. Prior to performing procedure, each sample was filtered
150
through a 0.45 µm membrane filter and then was used for analysis. The spiked samples were
151
extracted using the optimized procedure. The real aqueous samples were spiking with standard at
152
concentrations of 0.0005 ng mL−1, 0.01 ng mL-1 and 0.50 ng mL−1. The spiked samples were
153
analyzed using the optimized procedure and then analyzed using Luminometer. The
154
experimental results do not show the presence of any 2-CEES or their residues in the river water
155
sample of this work. The results (Table I) indicated that the recoveries for spiked environmental
156
aqueous samples were in the range of 98.4 - 103.6 %. These results show that the matrices used
157
in this study, had little effect on procedure. Therefore, presented CL method can be used for the
158
determination of 2-CEES in aqueous samples.
159 160
Conclusion
161
Since Ag NPs shows stronger CL catalytic ability than those of gold and Pt nanoparticles,
162
in this study Ag NPs-catalyzed luminol–AgNO3 reaction was employed for the determination of
163
2-chloroethyl ethyl sulphide. The method is on the basis of the inhibition of the Ag NPs
164
catalyzed luminol- AgNO3 reaction by 2-CEES. Under the optimum conditions, measuring
165
shows good selectivity and sensitivity.
166
8
167
References
168
[1] H.O. Albrecht, Z. Phys. Chem. 136 (1928) 321-324.
169
[2] E.H. White, D.F. Rosewell, Chemi- and Bioluminescence. J.G. Burr (Ed.), Marcel Decker,
170
New York, pp. 215–244. 1985.
171
[3] K. Robards, P.J. Worsfold, Anal. Chim. Acta. 266 (1992) 147-152.
172
[4] M. Rahimi-Nasrabadi, S.M. Pourmortazavi, S.A. Sadat Shandiz, F. Ahmadi, H. Batooli, Nat.
173 174 175
Prod. Res. 28 (2014) 1964–1969. [5] SM Pourmortazavi, M Taghdiri, V Makari, M Rahimi-Nasrabadi, Spectrochim Acta A 136 (2015) 1249-1254
176
[6] Z.F. Zhang, H. Cui, M.J. Shi, Phys. Chem. Chem. Phys. 8 (2006) 1017–21.
177
[7] W. Wang, T. Xiong, H. Cui, Langmuir 24 (2008) 2826–33.
178
8] C.F. Duan, Y.Q. Yu, H. Cui, Analyst 133 (2008) 1250–55.
179
[9] H. Cui, J.Z. Guo, N. Li, L.J. Liu, J. Phys. Chem. C 112 (2008) 11319–23.
180
[10] Z.F. Zhang, H. Cui, M.J. Shi, Phys. Chem. 8 (2006) 1017–21.
181
[11] W. Wang, T. Xiong, H. Cui, Langmuir 24 (2008) 2826–33.
182
[12] S.L. Xu, H. Cui, Luminescence 22 (2007) 77–87.
183
[13] H. Chen, F. Gao, R. He, D.X. Cui, J. Colloid Interface Sci. 315 (2007) 158–163.
184
[14] Z.F. Zhang, H. Cui, C.Z. Lai, L.J. Liu, Anal. Chem. 77 (2005) 3324–29.
185
[15] L.R. Luo, Z.J. Zhang, L.Y. Hou, Anal. Chim. Acta 584 (2007) 106–111.
186
[16] J.Z. Guo, H. Cui, W. Zhou, W. Wang, J. Photochem. Photobiol. A 193 (2008) 89–96.
187
[17] J.Z. Guo, H. Cui, J. Phys. Chem. C 11 (2007) 12254–59.
9
188
[18] L. Wang, P. Yang, Y.X. Li, H.Q. Chen, M.G. Li, F.B. Luo, Talanta 72 (2007) 1066–72.
189
[19] Z.F. Zhang, H. Cui, C.Z. Lai, L.J. Liu, Anal. Chem. 77 (2005) 3324–29.
190
[20] S. Xu, H. Cui, Luminescence 22 (2007) 77–87.
191
[21] J.Z. Guo, H. Cui, W. Zhou, W. Wang, J. Photochem. Photobiol. A 193 (2008) 89–96.
192
[22] Y.G. Sun, Y.N. Xia, J. Am. Chem. Soc. 126 (2004) 3892-3901.
193
[23] V.S. Virendra, K.N. Anil, M. Boopathi, P. Pandey, S.R. Beer, Sensor. Actuat. B: Chem. 161
194
(2012) 1000–1009.
195
[24] D.B. Mawhinney, J.A. Rossin, K. Gerhart, J.T. Yates, Langmuir 15 (1999) 4789–95.
196
[25] J.H. Sharp, M. Abkowitz, J. Phys. Chem. 77 (1973) 477–481.
197
[26] W.P. Carey, B.R. Kowalski, Anal. Chem. 50 (1986) 3077–84.
198
[27] O.S. Milanko, S.A. Milinkovic, L.V. Rajakovic, Anal. Chim. Acta. 269 (1992) 289–300.
199
[28] S.W. Zhang, T.M. Swager, J. Am. Chem. Soc. 25 (2003) 3420–21.
200
[29] L. Bertilsson, K. Potje-Kamloth, H.D. Liess, B. Liedberg, Langmuir 15 (1999) 1128–35.
201
[30] R.M. Black, R.J. Clarke, R.W. Read, M.T.J. Reid, J. Chromatogr. A 662 (1994) 301–321.
202
[31] P.A. D’agostino, L.R. Provost, P.W. Brooks, J. Chromatogr. 541 (1991) 121–130.
203
[32] C.S. Kim, R.J. Lad, C.P. Tripp, Sens. Actuators B Chem. 76 (2001) 442–448.
204
[33] K. Tuovinen, H. Paakkanen, O. Hanninen, Anal. Chim. Acta. 440 (200) 151–159.
205
[34] W.E. Steiner, B.H. Clowers, L.H. Matz, W.F. Siems, H.H. Hill, Anal. Chem. 74 (2002)
206 207 208 209 210
4343–52. [35] D.H. Ellison, Handbook of Chemical and Biological Warfare Agents. CRC Press. Boca Raton. 1999. [36] J.W. Grate, S.L. Rose-Pehrsson, D.L. Venezky, M. Klusty, H. Wohltjen, Anal. Chem. 65 (1993) 1868–81. 10
211
[37] J.W. Grate, R.A. McGill, Anal. Chem. 67 (1995) 4015–19.
212
[38] V.V. Pinto, M.J. Ferreira, R. Silva, H.A. Santos, F. Silva, C.M. Pereira, Colloid Surfaces A
213 214
364 (2010) 19–25. [39] Z. Sheng, H. Han, G. Yang, G. Luminescence. 26 (2011) 196–201.
215 216
11
217
Figure legends:
218
Fig. 1. UV-Vis spectra of Ag NPS
219
Fig. 2. TEM images of Ag NPs
220
Fig. 3. The average size of nanoparticle with DLS spectrum
221
Fig.4. CL intensity as a function of time; AgNO3 (1.69 µg mL-1), luminol (1.77 mg mL-1), and
222
pH=12.0 A) In the absence of nanoparticle, B) In the presence of nanoparticle
223
Fig. 5. Mechanism of fluorescence quenching
224
Fig. 6. The Influence of reaction conditions on the CL intensity of the luminal- AgNO3 CL
225
reaction catalyzed by Ag NPs. (A) pH effect: luminol, 1.77 mg mL-1 ; AgNO3, 1.69 µg mL-1
226
.NP,100 µ
227
pH=12.0;NP,100 µ liter(C) Effect of luminol concentration: pH=12.0 ; 1.69 µg mL-1.
228
NP,100 µ liter (D) AgNPs concentration: luminol, 1.77 mg mL-1; pH 12.0; 1.69 µg mL-1.
liter (B)
Effect of AgNO3 concentration: luminol, 1.77 mg mL-1,
229
Fig. 7. Calibration curve. CL intensity as a function of 2-CEES concentration (ng mL-1).
230
Conditions: luminol, 1.77 mg mL-1; pH 12.0; AgNO3 1.69 µg mL-1.; Ag colloid 100 µ liter.
231
12
232
Table I. Determination of 2-CEES in real water sample
Sample (River water)
233
Sample1 Sample2 Sample3 * ± Standard deviation (n=5)
Injected amount (ng mL-1) 0.50 0.01 0.0005
234 235
13
This method (ng mL-1)* 4.92 ± 0.03% 0.98 ± 0.026% 0.000518 ± 0.042%
Recovery (%) 98.4 98.6 103.6
236 237 238 239 240 241 242 243 244 245 246
Fig. 1
247 248
14
249 250
Fig. 2
251
15
252 253 254 255 256 257 258
Fig. 3
259 260
16
261
262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277
Fig. 4
278
17
O
O NH NH
279
NH2
+
OH
N
-
NH
O
NH2
O
O N
-
+ + Ag + OH NH
280
+
H2 O
O -
. Ag nanoparticle
N N
NH2 O
NH2 O
281
282
18
+
+ Ag + H2O
283 284 285
NH2
Cl
NH
2-CEES
.. S
CH3
2-CEES
287 288
NH
+
NH O
O
AgNPs
AgNPs
NH
AgNO3 +
286
NH2
O
Fig. 5
289
19
O
+ AgNO3
290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310
Fig. 6
311 312 313 314 315 316
20
317 318 319 320 321
322 323 324 325
Fig. 7
326 327 328 329 330 331 332 333 334 335 21
NH2
NH
+
NH O
O
AgNPs
AgNPs
NH
AgNO3 +
336
NH2
O
Cl
.. S
NH
2-CEES CH3
2-CEES
337
22
O
+ AgNO3
338
•
(2-CEES) could inhibit the chemiluminescence of the luminol-AgNO3 system
339
•
2-CEES was determined based on chemiluminescence quenching of luminol-AgNO3 system
340
•
The presented method is simple, convenient, rapid and sensitive
341
•
The presented method offer low LODs and good repeatability and recoveries
342
343
23
S1386-1425(15)00161-4 http://dx.doi.org/10.1016/j.saa.2015.02.009 SAA 13299
To appear in:
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Received Date: Revised Date: Accepted Date:
11 November 2014 29 January 2015 4 February 2015
Please cite this article as: B. Maddah, J. Shamsi, M. Jam Barsang, M. Rahimi-Nasrabadi, The chemiluminescence determination of 2-chloroethyl ethyl sulphide using luminol– AgNO3 –silver nanoparticls system, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2015), doi: http://dx.doi.org/10.1016/j.saa.2015.02.009
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
The chemiluminescence determination of 2-chloroethyl ethyl sulphide using luminol–
2
AgNO3–silver nanoparticls system
3
Bozorgmehr Maddah, Javad Shamsi, Mehran Jam Barsang and Mehdi Rahimi-Nasrabadi*
4
Nanoscience Center, Imam Hossein University, Tehran, Iran
5 6
*
1
Corresponding author. Tel.: +98-2177594707; [email protected] (M. Rahimi-Nasrabadi)
Fax:
+98-2177594707;
Email:
7
Abstract:
8
A highly sensitive chemiluminescence (CL) method for the determination of 2-chloroethyl ethyl
9
sulphide (2-CEES) was presented. It was found that 2-chloroethyl ethyl sulphide (2-CEES) could
10
inhibit the CL of the luminol-AgNO3 system in the presence of silver nanoparticles in alkaline
11
solution, which made it applicable for determination of 2-CEES. The presented method is
12
simple, convenient, rapid and sensitive. Under the optimized conditions, the calibration curve
13
was linear in the range of 0.0001-1 ng mL-1, with the correlation coefficient of 0.992; while the
14
limit of detection (LOD), based on signal-to-noise ratio (S/N) of 3, was 6×10-6 ng mL-1. Also, the
15
relative standard deviation (RSD, n=5) for determination of 2-CEES (0.50 ng mL-1) was 3.1%.
16
The method was successfully applied for the determination of 2-CEES in environmental aqueous
17
samples.
18 19
Keywords: Chemical warfare agent (CWA); 2-Chloroethyl ethyl sulfide; Chemiluminescence; Ag
20
NPs; AgNO3; luminal
21 22
Introduction
23
In recent years, extremely sensitive analytical techniques based on chemiluminescence
24
(CL) and bioluminescence systems have received considerable attention. Simplicity of detection,
25
low limit of detection, large calibration ranges and short analysis times are some of the
26
characteristics that make the methods attractive. Since it was first reported by Albrecht [1] in
27
1928, the CL resulting from the reaction of luminol (5-amino-2,3-dihydrophthalzine-1,4-dione)
28
and an oxidant (H2O2 in particular), in a strongly basic medium, has been extensively studied [2]
29
and applied to the determination of several inorganic species [3].
2
30
In recent years, many attentions have been paid to use metal nanoparticles (MNPs) as
31
nanocatalysts in CL reactions [4-7], because of their unique physical and chemical properties and
32
great analytical potential [8-18]. Cui et al. found that the gold [19], platinum [20] and silver [21]
33
NPs could catalyze and enhance luminol–AgNO3 CL reaction. Sun and Xia [22] also found that
34
Ag NPs exhibited a better CL catalytic ability than gold and platinum NPs. AgNO3 in presence
35
of silver can oxidize water; producing hydroxyl radicals, more easily than gold, since its
36
oxidation potential is lower than that of gold.
37
2-CEES (C4H9ClS) is the stimulants of sulfur mustard and it is important to develop the
38
detectors to detect CWA like sulfur mustard [23]. 2-CEES contains a single chlorine atom on the
39
carbon relative to the sulfur atom (mustard is 2,2-dichlorodiethyl sulfide) [24]. The 2-CEES
40
molecule is much less toxic. Thus, it is expected that 2-CEES closely mimics the reactivity of
41
mustard gas [25]. Other studies have reported various principles and devices for the detection of
42
CWA and stimulants, such as piezoelectric quartz crystal microbalance (QCM), sensors,
43
spectroscopic and chromatographic-based techniques [30-32], including ion mobility mass
44
spectrometry [33,34], enzyme-based [35] and surface acoustic wave (SAW) sensors [36,37].
45
According to the available literature and to the best of our knowledge, no report is available
46
so far for the sensing of 2-CEES based on CL method. In this work, the effect of Ag NPs on the
47
luminol-AgNO3 system was investigated. It was found that Ag NPs could act as a nanocatalyst
48
on the luminol-AgNO3 system to generate CL. Based on the catalytic effect of Ag NPs, a new,
49
rapid, simple, sensitive and inexpensive method was presented for the determination of 2-CEES.
50 51
Experimental
52
Materials
3
53
Silver
nitrate
(AgNO3),
sodium
borohydride
(NaBH4),
trisodium
citrate
54
(C6H5Na3O7·2H2O), sodium hydroxide (NaOH) were purchased from Merck (Darmstadt,
55
Germany). Luminol was purchased from Fluka Corporation (Buchs, Switzerland). All reagents
56
were analytical grade and used without further purification.
57
A 1.77 mg mL-1 stock solution of luminol (3-aminophthalhydrazide) was prepared by
58
dissolving luminol in 0.004 mg mL-1 NaOH. Working solutions of luminol were prepared by
59
diluting the stock solution with appropriate amounts of NaOH solution. Doubly distilled water
60
was used throughout.
61 62
Apparatus
63
The CL intensity was measured and recorded with a Berthold (USA) Luminometer. CL
64
intensity was recorded as a function of time, the time resolution of the apparatus was 0.5 second.
65
UV–visible adsorption spectra were recorded on a Hitachi U-3900H UV–Vis Spectrophotometer
66
(Tokyo, Japan) with 1 cm quartz cells at room temperature. Determining the particle size
67
distribution of the sample suspended in distilled water was performed by dynamic light
68
scattering (DLS) using Malvern instrument (England). TEM image was obtained using a
69
transmission electron microscope (Ziess- EM900). Prior to the measurement, the sample was
70
treated with coating on the Cu-carbon coated grid.
71 72
Preparation of Silver NPs
73
Ag NPs (~5 nm in diameter) were synthesized by the reduction of AgNO3 with NaBH4
74
and stabilized using tri sodium citrate (Na3C6 H5O7) according to the literature [38]. 100 mL of a
75
solution containing AgNO3 and Na3C6 H5O7, both in a concentration of 0.25 mM, was prepared
4
76
and stirred for 30 S. Then, 3 mL solution of NaBH4 (0.037 mg mL-1, freshly prepared) was added
77
quickly to the mixture. The solution immediately turned to yellow and was stirred for 60 S and
78
then stored in refrigerator at 4 °C before use. Ag NPS were characterized by UV-vis
79
spectrophotometer and the surface Plasmon resonance band of silver nanoparticles appears at
80
400 nm (Fig. 1). Furthermore, the prepared Ag NPs were characterized by TEM for definition of
81
its morphology; the TEM image confirms that synthesized Ag NPs have an average size about 5
82
nm (Fig. 2). Meanwhile, particle size distribution of Ag NPs was obtained as shown in Fig. 3. As
83
could be seen, this figure confirms the TEM data (Fig. 2) and most frequency numbers are
84
corresponding to the particles with size of 5 nm.
85 86
CL Measurement
87
100 µL of phosphate buffer and 100 µL Ag NPs solution with certain size was injected
88
into a 40×14-mm quartz tube (used as CL detector). Then, 0.5 mL 1.77 mg mL-1 luminol
89
solution was mixed with 0.5 mL 16.9 µg mL-1 AgNO3 solution and 200 µL of luminol-AgNO3
90
mixture were injected into the quartz tube. The CL signal was measured and recorded with the
91
Luminometer. To optimize the reaction conditions, the concentration of each reactant was varied
92
whilst holding the others constant. Ultimately, the CL intensity as a function of time was
93
recorded in the presence of various trace amounts of 2-CEES. Inhibition in CL intensity in the
94
presence of trace 2-CEES material was considered as an analytical signal.
95 96 97
5
98
Results and discussion
99 100
Inhibition of the Ag NPs-catalysed luminol–AgNO3 reaction by 2-CEES
101
The effect of 2-CEES on the luminol CL reaction catalyzed by Ag NPs was studied using
102
the static injection analysis process. As illustrated in Fig. 4 the CL intensity of luminol-AgNo3
103
reaction was significantly enhanced in the presence of Ag NPs. Interestingly, the CL intensity of
104
luminol-AgNO3 system (catalyzed by Ag NPs) was significantly decreased by addition of 2-
105
CEES. Results revealed that the extent of inhibition is related to the concentration of 2-CEES in
106
the sample. According to the results obtained by Sheng et al [39] it can be deduced that the
107
decreasing of CL intensity can be attributed to high affinity 2-CEES to silver NPs. The sulfur
108
atoms can interaction with Ag NPs and its catalystic feature as luminescence decreased in
109
various concentration with comparison to the luminescence while 2-CEES has not presented.
110
The mechanism of chemiluminescence is based on the oxidation of luminol with AgNO3
111
in alkaline solution. When the silver nanoparticles (NPs) were added to the solution the CL
112
remarkably enhanced. The silver nanoparticles may catalyze the reduction of AgNO3 by luminol.
113
The product luminol radicals reacted with the dissolved oxygen, to produce a strong CL
114
emission. As a result, the CL intensity was substantially increased. While by addition of 2-CEES
115
to the solution containing the luminol-AgNO3-Ag NPs, the 2-CEES adsorbed by the Ag NPs and
116
its catalyzing effect was reduced and resulted to quenching of CL (Fig. 5).
117 118 119
Optimization conditions of CL reaction
120
In order to achieve the highest sensitivity, the reaction conditions of the Ag NPs-
121
catalyzed luminol-AgNO3 system, such as pH, AgNO3, luminol and Ag NPs concentration were 6
122
investigated. The influence of pH on the CL was examined in the range of 9.0-13.0 (Fig. 6A).
123
The highest CL intensity was obtained at pH 12.0. Therefore, pH was adjusted at 12 using
124
phosphate buffer for the subsequent experiments. Results indicated that at the pH higher than
125
12.0, the CL intensity decreases with increasing pH. The effect of AgNO3 concentration on the
126
CL was studied in the range of 0.21 – 8.49 µg mL-1. As shown in Fig. 6B, the CL intensity
127
increased with increasing AgNO3 concentration up to 1.69 µg mL-1 and decrease in the more
128
AgNO3 concentration. The luminol concentration was varied in the range 0.17-1.77 mg mL-1.
129
The CL signal increases linearly with the increasing luminol concentration up to 1.77 mg mL-1.
130
Since the CL signal at luminol concentration of 1.77 mg mL-1 was reached to the highest
131
detectable level of the luminometer; hence, 1.77 mg mL-1 of luminol concentration was used for
132
further experiments (Fig. 6C). Finally, the influence of the concentration of Ag NPs was also
133
investigated (Fig. 6D). As can be seen, the CL intensity increased significantly with the
134
concentration of Ag NPs. The CL signal was reached to the highest detectable level of the
135
luminometer in 100 µL of Ag NPs volume; hence, 100 µL was selected for next experiments. As
136
a result, the optimized conditions for the luminol-AgNO3-silver colloids CL system were as
137
follows: 1.77 mg mL-1 luminol in pH 12.0, 1.69 µg mL-1 and 100 µL of Ag NPs.
138 139
Analytical features of method
140
Calibration curve (i.e., the CL intensity as function of 2-CEES) was obtained by
141
analyzing standard solutions containing different concentrations of the 2-CEES under the
142
optimized experimental conditions. Calibration curve (Fig. 7) was linear in the range of 0.0001-1
143
ng mL-1 with a regression equation of y=11.75x+309.30 (x, ng mL-1; R2 =0.992). The limit of
7
144
detection (LOD), based on signal-to-noise ratio (S/N) of 3, was 6×10-6 ng mL -1. The relative
145
standard deviation (RSD, n=5) for determination of 2-CEES (0.50 ng mL-1) was 3.1%.
146 147
Application of the procedure to real aqueous sample analysis
148
River water sample was collected in 1 L amber glass bottles (without any further
149
treatment), and cooled in refrigerator. Prior to performing procedure, each sample was filtered
150
through a 0.45 µm membrane filter and then was used for analysis. The spiked samples were
151
extracted using the optimized procedure. The real aqueous samples were spiking with standard at
152
concentrations of 0.0005 ng mL−1, 0.01 ng mL-1 and 0.50 ng mL−1. The spiked samples were
153
analyzed using the optimized procedure and then analyzed using Luminometer. The
154
experimental results do not show the presence of any 2-CEES or their residues in the river water
155
sample of this work. The results (Table I) indicated that the recoveries for spiked environmental
156
aqueous samples were in the range of 98.4 - 103.6 %. These results show that the matrices used
157
in this study, had little effect on procedure. Therefore, presented CL method can be used for the
158
determination of 2-CEES in aqueous samples.
159 160
Conclusion
161
Since Ag NPs shows stronger CL catalytic ability than those of gold and Pt nanoparticles,
162
in this study Ag NPs-catalyzed luminol–AgNO3 reaction was employed for the determination of
163
2-chloroethyl ethyl sulphide. The method is on the basis of the inhibition of the Ag NPs
164
catalyzed luminol- AgNO3 reaction by 2-CEES. Under the optimum conditions, measuring
165
shows good selectivity and sensitivity.
166
8
167
References
168
[1] H.O. Albrecht, Z. Phys. Chem. 136 (1928) 321-324.
169
[2] E.H. White, D.F. Rosewell, Chemi- and Bioluminescence. J.G. Burr (Ed.), Marcel Decker,
170
New York, pp. 215–244. 1985.
171
[3] K. Robards, P.J. Worsfold, Anal. Chim. Acta. 266 (1992) 147-152.
172
[4] M. Rahimi-Nasrabadi, S.M. Pourmortazavi, S.A. Sadat Shandiz, F. Ahmadi, H. Batooli, Nat.
173 174 175
Prod. Res. 28 (2014) 1964–1969. [5] SM Pourmortazavi, M Taghdiri, V Makari, M Rahimi-Nasrabadi, Spectrochim Acta A 136 (2015) 1249-1254
176
[6] Z.F. Zhang, H. Cui, M.J. Shi, Phys. Chem. Chem. Phys. 8 (2006) 1017–21.
177
[7] W. Wang, T. Xiong, H. Cui, Langmuir 24 (2008) 2826–33.
178
8] C.F. Duan, Y.Q. Yu, H. Cui, Analyst 133 (2008) 1250–55.
179
[9] H. Cui, J.Z. Guo, N. Li, L.J. Liu, J. Phys. Chem. C 112 (2008) 11319–23.
180
[10] Z.F. Zhang, H. Cui, M.J. Shi, Phys. Chem. 8 (2006) 1017–21.
181
[11] W. Wang, T. Xiong, H. Cui, Langmuir 24 (2008) 2826–33.
182
[12] S.L. Xu, H. Cui, Luminescence 22 (2007) 77–87.
183
[13] H. Chen, F. Gao, R. He, D.X. Cui, J. Colloid Interface Sci. 315 (2007) 158–163.
184
[14] Z.F. Zhang, H. Cui, C.Z. Lai, L.J. Liu, Anal. Chem. 77 (2005) 3324–29.
185
[15] L.R. Luo, Z.J. Zhang, L.Y. Hou, Anal. Chim. Acta 584 (2007) 106–111.
186
[16] J.Z. Guo, H. Cui, W. Zhou, W. Wang, J. Photochem. Photobiol. A 193 (2008) 89–96.
187
[17] J.Z. Guo, H. Cui, J. Phys. Chem. C 11 (2007) 12254–59.
9
188
[18] L. Wang, P. Yang, Y.X. Li, H.Q. Chen, M.G. Li, F.B. Luo, Talanta 72 (2007) 1066–72.
189
[19] Z.F. Zhang, H. Cui, C.Z. Lai, L.J. Liu, Anal. Chem. 77 (2005) 3324–29.
190
[20] S. Xu, H. Cui, Luminescence 22 (2007) 77–87.
191
[21] J.Z. Guo, H. Cui, W. Zhou, W. Wang, J. Photochem. Photobiol. A 193 (2008) 89–96.
192
[22] Y.G. Sun, Y.N. Xia, J. Am. Chem. Soc. 126 (2004) 3892-3901.
193
[23] V.S. Virendra, K.N. Anil, M. Boopathi, P. Pandey, S.R. Beer, Sensor. Actuat. B: Chem. 161
194
(2012) 1000–1009.
195
[24] D.B. Mawhinney, J.A. Rossin, K. Gerhart, J.T. Yates, Langmuir 15 (1999) 4789–95.
196
[25] J.H. Sharp, M. Abkowitz, J. Phys. Chem. 77 (1973) 477–481.
197
[26] W.P. Carey, B.R. Kowalski, Anal. Chem. 50 (1986) 3077–84.
198
[27] O.S. Milanko, S.A. Milinkovic, L.V. Rajakovic, Anal. Chim. Acta. 269 (1992) 289–300.
199
[28] S.W. Zhang, T.M. Swager, J. Am. Chem. Soc. 25 (2003) 3420–21.
200
[29] L. Bertilsson, K. Potje-Kamloth, H.D. Liess, B. Liedberg, Langmuir 15 (1999) 1128–35.
201
[30] R.M. Black, R.J. Clarke, R.W. Read, M.T.J. Reid, J. Chromatogr. A 662 (1994) 301–321.
202
[31] P.A. D’agostino, L.R. Provost, P.W. Brooks, J. Chromatogr. 541 (1991) 121–130.
203
[32] C.S. Kim, R.J. Lad, C.P. Tripp, Sens. Actuators B Chem. 76 (2001) 442–448.
204
[33] K. Tuovinen, H. Paakkanen, O. Hanninen, Anal. Chim. Acta. 440 (200) 151–159.
205
[34] W.E. Steiner, B.H. Clowers, L.H. Matz, W.F. Siems, H.H. Hill, Anal. Chem. 74 (2002)
206 207 208 209 210
4343–52. [35] D.H. Ellison, Handbook of Chemical and Biological Warfare Agents. CRC Press. Boca Raton. 1999. [36] J.W. Grate, S.L. Rose-Pehrsson, D.L. Venezky, M. Klusty, H. Wohltjen, Anal. Chem. 65 (1993) 1868–81. 10
211
[37] J.W. Grate, R.A. McGill, Anal. Chem. 67 (1995) 4015–19.
212
[38] V.V. Pinto, M.J. Ferreira, R. Silva, H.A. Santos, F. Silva, C.M. Pereira, Colloid Surfaces A
213 214
364 (2010) 19–25. [39] Z. Sheng, H. Han, G. Yang, G. Luminescence. 26 (2011) 196–201.
215 216
11
217
Figure legends:
218
Fig. 1. UV-Vis spectra of Ag NPS
219
Fig. 2. TEM images of Ag NPs
220
Fig. 3. The average size of nanoparticle with DLS spectrum
221
Fig.4. CL intensity as a function of time; AgNO3 (1.69 µg mL-1), luminol (1.77 mg mL-1), and
222
pH=12.0 A) In the absence of nanoparticle, B) In the presence of nanoparticle
223
Fig. 5. Mechanism of fluorescence quenching
224
Fig. 6. The Influence of reaction conditions on the CL intensity of the luminal- AgNO3 CL
225
reaction catalyzed by Ag NPs. (A) pH effect: luminol, 1.77 mg mL-1 ; AgNO3, 1.69 µg mL-1
226
.NP,100 µ
227
pH=12.0;NP,100 µ liter(C) Effect of luminol concentration: pH=12.0 ; 1.69 µg mL-1.
228
NP,100 µ liter (D) AgNPs concentration: luminol, 1.77 mg mL-1; pH 12.0; 1.69 µg mL-1.
liter (B)
Effect of AgNO3 concentration: luminol, 1.77 mg mL-1,
229
Fig. 7. Calibration curve. CL intensity as a function of 2-CEES concentration (ng mL-1).
230
Conditions: luminol, 1.77 mg mL-1; pH 12.0; AgNO3 1.69 µg mL-1.; Ag colloid 100 µ liter.
231
12
232
Table I. Determination of 2-CEES in real water sample
Sample (River water)
233
Sample1 Sample2 Sample3 * ± Standard deviation (n=5)
Injected amount (ng mL-1) 0.50 0.01 0.0005
234 235
13
This method (ng mL-1)* 4.92 ± 0.03% 0.98 ± 0.026% 0.000518 ± 0.042%
Recovery (%) 98.4 98.6 103.6
236 237 238 239 240 241 242 243 244 245 246
Fig. 1
247 248
14
249 250
Fig. 2
251
15
252 253 254 255 256 257 258
Fig. 3
259 260
16
261
262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277
Fig. 4
278
17
O
O NH NH
279
NH2
+
OH
N
-
NH
O
NH2
O
O N
-
+ + Ag + OH NH
280
+
H2 O
O -
. Ag nanoparticle
N N
NH2 O
NH2 O
281
282
18
+
+ Ag + H2O
283 284 285
NH2
Cl
NH
2-CEES
.. S
CH3
2-CEES
287 288
NH
+
NH O
O
AgNPs
AgNPs
NH
AgNO3 +
286
NH2
O
Fig. 5
289
19
O
+ AgNO3
290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310
Fig. 6
311 312 313 314 315 316
20
317 318 319 320 321
322 323 324 325
Fig. 7
326 327 328 329 330 331 332 333 334 335 21
NH2
NH
+
NH O
O
AgNPs
AgNPs
NH
AgNO3 +
336
NH2
O
Cl
.. S
NH
2-CEES CH3
2-CEES
337
22
O
+ AgNO3
338
•
(2-CEES) could inhibit the chemiluminescence of the luminol-AgNO3 system
339
•
2-CEES was determined based on chemiluminescence quenching of luminol-AgNO3 system
340
•
The presented method is simple, convenient, rapid and sensitive
341
•
The presented method offer low LODs and good repeatability and recoveries
342
343
23
