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The in situ detection of smoking in public area by laser-induced breakdown spectroscopy
Journal Pre-proof The in situ detection of smoking in public area by laser-induced breakdown spectroscopy Qihang Zhang, Yuzhu Liu, Wenyi Yin, Yihui Yan, Lei Li, Guanhua Xing PII:
S0045-6535(19)32423-3
DOI:
https://doi.org/10.1016/j.chemosphere.2019.125184
Reference:
CHEM 125184
To appear in:
ECSN
Received Date: 12 July 2019 Revised Date:
13 October 2019
Accepted Date: 19 October 2019
Please cite this article as: Zhang, Q., Liu, Y., Yin, W., Yan, Y., Li, L., Xing, G., The in situ detection of smoking in public area by laser-induced breakdown spectroscopy, Chemosphere (2019), doi: https:// doi.org/10.1016/j.chemosphere.2019.125184. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2019 Published by Elsevier Ltd.
1
The in situ Detection of Smoking in Public Area by
2
Laser-induced Breakdown Spectroscopy
3
Qihang Zhang a, Yuzhu Liua,b,*, Wenyi Yina, Yihui Yana, Lei Lic and Guanhua Xingd
4 5 ， 7 8 9 10 11
a
Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing University of Information Science & Technology, Nanjing 210044, P. R. China b
Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology (CICAEET), Nanjing 210044, P. R. China
c
Institute of Mass Spectrometer and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, P.R. China d
China National Environmental Monitoring Center, Beijing 100012, P. R. China
12
Abstract: The cigarette smoke in public area could be harmful to the non-smokers. In this paper,
13
laser-induced breakdown spectroscopy (LIBS) is applied to the in situ detection of the cigarette
14
smoke in public area, and the single particles aerosol mass spectrometer (SPAMS) is utilized to aid
15
the elemental analysis as well as realize the isotope detection. According to the obtained emission
1，
spectra, the smoke consists of Mg, Ca, Sr, Na, K elements which are absent in air, and the
17
concentrations of H2O and CO2 in smoke increase obviously. Moreover, the cigarette ash after
18
burning is taken as the sample for off-line detection and several heavy metal elements are detected.
19
The comparison between the spectra of cigarette smoke and ash shows that these two kinds of
20
detection are greatly different in terms of constituent and plasma status. In addition, the molecular
21
emission of Carbon-Nitrogen was observed in smoke spectrum, and the molecular vibrational and
22
rotational temperature of CN molecule was calculated. Finally, the LIBS and SPAMS were applied
23
to the semi-quantitative detection and isotope analysis of Pb in the smoke.
24
Keywords: Laser-induced breakdown spectroscopy, Single Particles Aerosol Mass Spectrometer,
25
in situ detection; smoke pollution; Pb
2， 27
1. Introduction
28
It is well-known that cigarette smoking is harmful for health due to the toxic ingredient of
29
cigarette. Moreover, the noxious smoke of the cigarette containing nicotine, tar, Pb, As and other
30
noxious ingredient also has pernicious effects on the non-smokers (Salvi et al.,2009). The research
31
also shows that the second-hand smoke could cause a wide range of adverse health effects,
32
including cancer, respiratory infections, heart attacks and other diseases (Glantz et al., 1991; Teo et
33
al., 2006; Öberg et al., 2011). Non-smokers exposed to second-hand smoke increase their heart
34
disease risk by 25–30% and their lung cancer risk by 20–30% (Barnoya et al., 2005).
*
Corresponding to author: Yuzhu Liu. E-mail: [email protected]
35
Accordingly, the smoking is strictly forbidden in most public area such as hospital, train
3，
station or office building all around the world with the purpose of eliminating such great damage
37
to the non-smokers. However, this significant prohibition is often ignored by some smokers, and
38
the smoke generated from their smoking could fill the whole of public area. Although the smoke
39
becomes thinner as time goes on, the damage still exists but the smell is no longer scented by the
40
non-smokers.
41
Therefore, it is of great significance to accurately evaluate the exposure to the cigarette
42
smoke of the people in the public area. While it is obviously not possible to adapt the method of
43
conventional chemical analysis because of their complicated procedure. Similarly, the present
44
optical methods such as atomic absorption spectrometry(AAS) (Dos Santos et al., 2017; Huang et
45
al., 2019), atomic fluorescence spectrometry(AFS) (Duan et al., 2017), and X-ray
4，
fluorescence(XRF) (Felix et al., 2018; Kapishnikov et al., 2017; Gama et al., 2017) also need
47
complex sample pretreatment or consume too much time. Therefore, it is not feasible to use these
48
methods for the in situ detection of smoking.
49
Laser-induced breakdown spectroscopy(LIBS) is an analytical method with many advantages
50
such as rapid and precise response, simultaneous multi-element analysis, high sensitivity (Viana et
51
al., 2019; Guo et al., 2017). Due to the merits above, it is widely applied to the component
52
analysis of coal, alloy and other inorganic substances (Rehan et al., 2018; Baudelet et al., 2010).
53
However, it could be troublesome to identify the spectral lines in LIBS spectrum when there exist
54
two or more possibilities. It is necessary to utilize other analytical method, such as mass spectrum,
55
to aid the analysis of LIBS. While the conventional mass spectrometer is not available to the in
5，
situ detection of cigarette smoke. Single particles aerosol mass spectrometer (SPAMS) has proven
57
to be a suitable method for the in situ component analysis in recent years (Li et al., 2016). It can be
58
applied to identify particle size and chemical composition from a single particle with extremely
59
high temporal and spatial resolution. Therefore, it could be an excellent choice to combine these
，0
two technique for the smoking detection.
，1
However, to our best knowledge, the in situ detection of the cigarette smoke by laser-induced
，2
breakdown spectroscopy combined with single particles aerosol mass spectrometer has never been
，3
addressed. In the present work, the LIBS and SPAMS were applied to the in situ detection of
，4
smoke in public area and the rapid evaluation of the exposure to cigarette smoke of the
，5
non-smokers.
，， ，7 ，8
2. Experimental section 2.1 LIBS setup
，9
The schematic diagram of the experimental setup is shown in Fig.1. The smoke is generated
70
from the burning cigarette. In order to realize the in situ detection, the laser pulse is directly
71
focused on the smoke, and the emission spectrum is obtained by the monitor(spectrometer). The
72
excitation laser employed in our work is a Q-switched Nd:YAG laser and it was operated at a
73
fundamental wavelength of 1064 nm; the energy is 260 mJ in a single laser pulse with a 6 ns
74
duration at a frequency of 10 Hz. The plasma radiation emission was directly collected by an
75
optical fiber coupled to a spectrometer with a spectral window ranging from 220 to 770 nm. The
7，
spectral resolution of the spectrometer is around 0.1 nm.
77 78 79
Fig.1 The schematic diagram of the experimental setup
2.2 SPAMS setup
80
The SPAMS setup has been introduced in detail in our previous paper (Li et al., 2011). The
81
single particles of the cigarette smoke in the size range of 0.1-2.0 µm were effectively drawn from
82
ambient atmosphere into the vacuum chamber, and then were gradually focused onto the axis of an
83
aerodynamic lens. The Nd:YAG laser (266 nm) employed as the excitation laser and the particles
84
were desorbed/ionized at the ion source region by the pulsed laser to get the mass spectrum, and
85
the energy of each pulse is approximately 520 µJ.
8， 87
3. Results and Discussion
88
3.1 The in situ elemental detection of smoke by LIBS
89
In order to simulate the detection in real environment condition, all the experiments in the
90
present work were operated in the air and the samples such as the cigarette smoke and ash were
91
detected by LIBS technique. Taking the cigarette smoke, ash as targets, the spectra of them were
92
obtained and analyzed, respectively.
93
The LIBS spectrum of cigarette smoke (labeled as Smoke On) were obtained and shown in
94
Fig.2. For comparison, the spectrum of the air without any cigarette smoke (labeled as Smoke Off)
95
was also put in the same figure. Before the analysis, to avoid the overlap of their spectral lines, the
9，
smoke spectrum was moved up in the direction of y-axis. The Fig.2 shows that the spectral lines in
97
the spectrum of cigarette smoke are much more than air spectrum. The observed spectral lines are
98
identified based on the NIST atomic spectra database and the results are marked in Fig.2
99
respectively. It can be found from the figure that the observed spectrum of the smoke consists of
100
the lines of C, Mg, Ca, Sr, Na, H, O, N, K, while only the lines of H, O, N elements can be
101
observed in the spectrum of air. In particular, the intensity of the Hα (656.28nm) line is much
102
lower than that in smoke’s spectrum, which can be explained by the lower concentration of H2O in
103
the air. Similarly, the C I (247.86nm) line in smoke’s spectrum is observed obviously while that in
104
air’s spectrum is too weak to be observed. Ca II 315.89nm Ca II 317.93nm 6000
4000
Smoke Off Smoke On
5000
3000
3000
2000
0
Mg II 279.55nm
-20
2000
2000
-40
Mg II 280.27nm
Sr II 407.77nm
-60
Sr I 421.55nm
-100
245 246 247 248 249 250
0
410
420
430
440
Hα 656.28nm
6000 2000
4000
O I 615.96nm
1000
Ca I 585.73nm
O I 715.67nm 2000
N I 746.831nm
Smoke Off Smoke On
1000
450
Wavelength/nm 6000
4000
K I 766.49nm K I 769.89nm
Na I 588.99nm Na I 589.59nm
Ca I 526.17nm Ca I 526.42nm Ca I 527.03nm
Ca I 559.01nm Ca I 559.45nm Ca I 559.85nm Ca I 560.13nm
3000
400
3000
Smoke Off Smoke On
Intensity/arb.units
340
N I 742.364nm N I 744.23nm
320
N I 665.28nm
300
Wavelength/nm
N I 672.48nm
280
N I 648.47nm
260
4000
2000
0 0
0 240
0 0
105 10， 107 108 109
500
1000
1000
Mg I 285.21nm
-80
1000
2000
C I 247.86nm
2000
Intensity/arb.units
3000
Ca I 422.67nm
4000
CaI: 428.30nm CaI: 428.94nm CaI: 429.90nm CaI: 430.25nm CaI: 430.77nm CaI: 431.87nm
Intensity/arb.units
4000
Intensity/arb.units
Smoke Off Smoke On
Ca I 442.54nm Ca I 445.59nm Ca I 443.49nm
6000
0 0
520
540
560
580
Wavelength/nm
600
600
620
640
660
680
700
720
740
760
780
Wavelength/nm
Fig.2 The LIBS spectra of air and cigarette smoke. (a)240-340nm, (b)400nm-450nm, (c)500nm-600nm, (d)600nm-780nm (left y-axis for smoke off, right y-axis for smoke on)
3.2 The spectra of cigarette smoke and ash
110
In this part, the cigarette ash after burning is taken as the sample for off-line detection by
111
LIBS technique in order to reveal the difference between the present detection with the off-line
112
detection. The spectra of smoke and ash ranged from 240nm to 780nm were shown as Fig.3. The
113
two spectra were merged in order to analyze the respective contents of cigarette smoke and ash as
114
well as the difference between them. The observed spectral lines in the spectra were also identified
115
according to the NIST database and the line information was added into the figure.
10000
2000
Mg I 285.21nm
4000
CN ∆ν=0
0 240
260
280
300
320
340
360
380
400
420
440
460
480
460
480
500
Ca I 487.81nm
Ca I 442.54nm Ca I 443.49nm Ca I 445.59nm
Ca I 422.67nm
Sr I 421.55nm
Sr II 407.77nm
Ca II 315.89nm Ca II 317.93nm
Ca II 393.37nm Ca II 396.85nm
2000
Mg I 382.94nm Mg I 383.23nm Mg I 383.83nm
Mg II 279.55nm
4000
Ca I 363.08nm Ca I 364.44nm
Ash
Ba I 493.41nm
6000
Mg II 280.27nm Mg I 285.21nm
Intensity/arb.units
Mg II 279.55nm Mg II 280.27nm
C I 247.86nm
6000
Ca II 393.37nm Ca II 396.85nm
Ca II 370.60nm Ca II 373.69nm
Ca II 315.89nm Ca II 317.93nm
Ca I 422.67nm
Smoke 8000
0 240
11，
260
280
300
320
340
360
380
400
420
440
500
8000 H 656.28nm
Smoke
α
N I 672.48nm
2000
N I 665.28nm
Ca I 559.01nm Ca I 559.45nm Ca I 559.85nm Ca I 560.13nm
4000
O I 715.37nm
0 740
760
K I 766.49nm K I 769.89nm
Ca I 672.08nm
720
Ca I 714.81nm
700
K I 693.88nm
680
K I 691.10nm
Ca I 647.17nm
660
Li I 670.77nm Ca I 671.77nm
2000
640 Ca I 646.26nm
Mg I 516.73nm Mg I 517.27nm Mg I 518.36nm
4000
620 Ca I 612.22nm
Ca II 645.69nm
Ca I 559.01nm Ca I 559.45nm Ca I 559.85nm Ca I 560.13nm
Ash 6000
600
Ca I 644.98nm
580
Ca I 643.91nm
560
Ca I 616.22nm Ca I 616.95nm
540
Ca I 610.27nm
520
Ca I 585.73nm Na I 588.99nm Na I 589.59nm
500 8000
Ca I:534.94nm
Intensity/arb.units
Ca I 585.73nm Na I 588.99nm Na I 589.59nm
6000
N I 742.36nm N I 744.23nm N I 746.83nm
Wavelength/nm
Ca I 732.39nm
0
117 118 119 120 121 122 123 124 125 12， 127 128 129 130 131 132 133
500
520
540
560
580
600
620
640
660
680
700
720
740
760
Wavelength/nm
Fig.3 The LIBS spectra of cigarette smoke and ash.
By comparing these two spectra, it was found that the spectral lines of Ca, Na, K and Mg were observed in both smoke’s spectrum and ash’s spectrum, indicating that these elements exist in smoke and ash, while the difference between these two spectra is significant. For instance, the C I (247.86nm), O I(715.37nm) and Hα (656.28nm) lines are completely invisible in ash’s spectrum, while these lines have high intensity in smoke’s spectrum. The burning of the cigarette makes C and H elements in the organics transfer to CO2, H2O, and they escape together with the smoke. Hence, there exists no C and H elements in the cigarette ash and their spectral lines are invisible in the spectrum. On the contrary, the spectral lines of several metal elements, such as Ba(493.41nm), Li(670.77nm), can only be observed in the spectrum of ash. Hence, there exists great difference between the constituents of cigarette smoke and ash. In addition, the comparison of the spectra above shows that, apart from the difference between the constituents of smoke and ash, there appears an interesting relationship between the intensities of ionic lines and atomic lines. Taking the spectral lines of Ca for instance, the atomic lines and ionic lines of Ca in the region from 365nm to 450nm are shown in Fig.4. It can be seen that the intensities of ionic lines (370.60nm, 373.69nm) in smoke are much higher than the
134 135 13，
intensities of Ca II lines in ash’s spectrum. Conversely, it is completely opposite in the case of atomic lines, the intensities of Ca I lines (430.25nm, 442.54nm, 443.49nm, 445.59nm, etc.) is far lower than those lines in ash’s spectrum. Similarly, the relationship between atomic lines and ionic
137
lines of Mg are the same as that of Ca as shown in Appendix(Fig.A.1). 6000
Smoke Ca I 428.30nm Ca I 428.94nm Ca I 429.90nm Ca I 430.25nm Ca I 430.77nm Ca I 431.87nm
Ca II 373.69nm
4000
Ca I 443.49nm Ca I 442.54nm Ca I 445.59nm
0 365
370
375
425
430
435
440
445
450
6000
Ash Ca I 428.30nm Ca I 428.94nm Ca I 429.90nm Ca I 430.25nm Ca I 430.77nm Ca I 431.87nm
Intensity/arb.units
Ca II 370.60nm
2000
4000
2000
Ca I 445.59nm Ca I 443.49nm Ca I 442.54nm
Ca II 370.60nm Ca II 373.69nm
0 365
138
370
375
425
430
435
440
445
450
Wavelength/nm
139
Fig.4 The atomic lines and ionic lines of Ca in the region from 365nm to 450nm
140 141 142 143 144 145 14， 147 148 149 150 151 152 153 154 155 15， 157 158 159
In consideration of the different matrix of these two samples, the matrix effect could be the primary cause accounting for this phenomenon. The matrix effect is of great significance to the LIBS detection and severely influences the accuracy of LIBS technique. It refers to the nonlinear laser-substance interaction in the process of laser ablation due to the difference in physical and chemical structure of the substance, which could lead to different spectral signals (Hahn et al., 2012). In this work, to be specific, the density of smoke is far lower than ash, which may cause higher temperature in smoke plasma. The extremely high temperature in the process of laser-matter interaction would make the atom ionize. The higher the plasma temperature is, the more likely the atoms are to ionize. Therefore, the intensity of ionic lines becomes higher with the increase of plasma temperature, while the intensity of atomic lines gets lower. To sum up the analysis and results, the on-line detection of smoke is quite different with the off-line detection of ash. 3.3 Molecular analysis of LIBS The LIBS technique is capable of elemental analysis as well as molecule analysis. In the present work, the LIBS technique was applied to the analysis of Carbon-Nitrogen free radical system. CN radical plays an important role in the combustion of carbides. In the outer layer of the plasma, the temperature is lower than the center, the molecular species could be direct released from the sample and combine with the molecular species in ambient atmosphere (Amiri et al., 2018). The formation of CN molecule can be elucidated by the reaction of carbon with atmospheric nitrogen (Kushwaha et al., 2008). In the most of cases, the CN emission band results
1，0 1，1 1，2 1，3 1，4 1，5 1，， 1，7 1，8 1，9 170 171 172 173 174 175 17， 177 178 179 180 181 182 183 184
from the recombination of C2 molecules released from aromatic rings and N2 molecules from air (St-Onge et al., 2002), where the C2 molecules being formed by recombination of carbon atoms and ions. However, as is shown in Fig.3, the C2 emission band (usually about 516.5nm) and the ionic lines of C element (usually about 426.7nm) are all absent in the spectrum of smoke. Therefore, the recombination of C2 molecules and N2 molecules could not be the explanation for the formation of CN molecules in this case, and there exists the other pathways. According to the literature (Lucena et al., 2011), it is likely that the CN molecules result from the direct reaction of C atoms from carbon dioxide or organic molecules and N atoms from air in the plasma. Hence, it is deduced that the CN emission band is intimately related to the organic constituent such as nicotine and benzopyrene in the smoke, and the analysis of CN radical is promising to be an effective method to detect the combustion of carbides in the air. The CN molecule emission band were observed in the spectrum of cigarette and shown in Fig.5. In order to accurately identify these lines, the CN molecule emission in air was simulated on LIFBASE, and the simulated emission band was also shown together with the experimental result. In addition, the CN emission band population distribution was shown in Appendix (Fig.A.2). The simulated result indicates that the emission band ranged from 375nm to 389nm generated by the B-X transition. And the intensities of the lines generated by the transition of the vibrational levels, which are distributed on the right of the band, are higher than those lines generated by the transition of the rotation levels. Hence, only the vibrational lines could be obviously distinguished, and the transition levels were identified and marked according to the simulated emission band. In addition, temperature is an important thermodynamic parameters and significant for studying the transitions of molecules and their chemical reactions. Hence, in this part, the vibrational temperature and rotational temperature are fitted on LIFBASE, and the result shows the vibrational and rotational temperatures are approximately 8000K and 7700K, respectively. 800
400
0-0 700
4-4 5-5 3-3
500
2-2
200
400
0
300 200
Intensity/arb.units
Intensity/arb.units
1-1
Exp Sim
600
-200
100 0
185 18， 187 188 189 190
376
378
380
382
384
386
388
-400 390
Wavelength/nm
Fig.5 The experimental and simulated emission band of CN
3.4 semi-quantitative detection and isotope analysis of Pb in smoke The experiment and analysis above preliminarily validate it achievable to qualitatively detect the ingredient of cigarette smoke in situ with LIBS method. However, the quantitative analysis of the toxic ingredient in smoke is essential as well as meaningful. In this part, we focused on Pb
191 192 193 194 195 19， 197 198 199 200 201
element due to its great damage on environment and human health. The cigarette samples to be measured were prepared by soaking them in the ሺܪܥଷ COOሻଶ Pb ∙ 3ܪଶ ܱ solution of different concentrations. The experiments were operated as before after the cigarettes were completely dried in the drying cabinet, and the spectra of these samples were obtained. Before the comparison, we normalized the spectra data by the intensity of the Ca II (396.85nm), which is close to the Pb I (405.78nm) line. Fig.6 shows the spectra in the region from 395nm to 450nm. As can be seen from the figure, there exists no signal of Pb I line when the Pb concentration equals to 0. While with the increase of the Pb concentration, the Pb I(405.78nm) appears and its intensity grows gradually. Therefore, it is deduced that the LIBS method in this work is promising to realize the quantitative analysis of Pb or other toxic ingredients in cigarette smoke in situ. Ca II 396.85nm
2.0 % 1.0 % 0.1 % 0.0 %
Pb I 405.78nm
Intensity/arb.units
Ca I 422.67nm
202 203 204 205 20， 207 208 209 210 211 212
400
410
420
430
440
450
Wavelength/nm
Fig.6 The variations of the spectral lines with the different concentration of Pb What’s more, as is well-known, there exist four isotopes (m/z=204,206,207,208) of Pb element. While it is impossible to detect the isotope of the single atom by LIBS technique. Hence, in order to analyze these isotopes of Pb, the smoke was also in situ detected by using a self-design Single Particles Aerosol Time of Flight Mass Spectrometer. The mass spectrometry can not only verify the result of the element analysis by LIBS, which is helpful for the identification of spectral lines, but also detect the abundance of the Pb in smoke samples. The mass spectrum of the isotope of Pb was shown as Fig.7. It is evident that the isotopes of Pb(206Pb+,207Pb+,208Pb+) can be obviously observed in the mass spectrum while the 204Pb cannot be observed for its low abundance in nature.
300
250
(53±4%)
200
208
+
Intensity/mV
Pb
150
(25±3%) 206
100
+ ±3%) Pb (22 207 + Pb
50
0 200
213 214 215 21， 217 218 219
201
202
203
204
205
206
207
208
209
210
M/Z
Fig.7 The mass spectrum of Pb isotope and abundance in the smoke Then the abundances of these three isotopes were calculated according to the intensities of peaks, and it shows that the abundance of Pb in smoke is similar to that in nature. However, it is well known that the isotopes obtained from different sources is likely to have different isotope ratios (Bol′shakov et al., 2015). Therefore, it can be deduced that the sources of the heavy mental elements can be determined according to the isotope abundance by using SPAMS.
220 221
Conclusion
222
In the present work, the LIBS was applied to the in situ detection of the cigarette smoke and
223
ash, and the SPAMS was used to aid the elemental analysis and realize the isotope detection of Pb
224
element. Based on the identification of the smoke spectrum, it can be found that the smoke from
225
burning consists of Ca, Na, Sr, K elements, which are nonexistent in the air. And the comparison
22，
with the air spectrum shows that the concentrations of the CO2 and H2O are much higher than
227
those in the air. In addition, the cigarette ash after burning is taken as the sample for off-line
228
detection, and then the ash spectrum is compared with smoke. It shows that there exists great
229
difference between the constituents of smoke and ash. The smoke spectrum contains spectral lines
230
of C, O, H elements while no Ba, Li lines exists, which can only be observed in the spectrum of
231
ash. Besides, the matrix effect of LIBS was also discussed by comparing the atomic lines and
232
ionic lines of Ca and Mg in cigarette smoke and ash. It shows that intensity of ionic line could be
233
higher in smoke than that in ash and the intensity of atomic lines could become lower because of
234
the high plasma temperature. Therefore, the results of on-line detection of smoke and off-line
235
detection of ash are greatly different. Moreover, the emission band of CN molecule in the region
23，
from 375nm to 389nm only appears in smoke spectrum, which is likely to generate from the direct
237
reaction of C atoms from carbon dioxide or organic molecules and N atoms from air in the plasma.
238
By simulated its emission band in LIFBASE, this band was identified and the vibrational and
239
rotational temperatures in our experiments are approximately 8000K and 7700K, respectively.
240
Then the Pb element in smoke was semi-quantitatively detected and the results shows that the with
241
the increase of the Pb concentration, the intensity of Pb I(405.78nm) grows gradually. Finally, the
242
Pb isotopes (206Pb,207Pb,
243
isotope was calculated. It is expected that LIBS combined with the SPAMS is promising to realize
244
the quantitative detection and source analysis of the toxic constituents in cigarette smoke in situ.
208
Pb) were in situ detected by the SPAMS, and the abundance of Pb
245 24，
Funding
247
National Key R&D Program of China (Grant No. 2017YFC0212700).
248 249
Acknowledgments
250
We would like to thank Miss Yuchen Hu for assisting in drawing Figure 1.
251 252
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253
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1.The first study of the in situ detection of smoking in public area by LIBS and SPAMS. 2.The smoking was firstly detected by both on-line and off-line optical methods. 3.The CN band for cigarette was firstly studied by combining theory and experiment. 4.The self-designed SPAMS was applied to the isotope abundance analysis.
Dear editor, All the authors agree to submit this manuscript entitled “The in situ Detection of Smoking in Public Area by Laser-induced Breakdown Spectroscopy” to Chemosphere. All the authors declare that there is no conflict of interest. And I signed in the name of all the following authors for the agreement.
Qihang Zhang a, Yuzhu Liua,b,1, Wenyi Yina, Yihui Yana, Lei Lic and Guanhua Xingd a
Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing University of
Information Science & Technology, Nanjing 210044, P. R. China b
Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology
(CICAEET), Nanjing 210044, P. R. China c
Institute of Mass Spectrometer and Atmospheric Environment, Guangdong Provincial Engineering Research
Center for On-line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, P.R. China d
China National Environmental Monitoring Center, Beijing 100012, P. R. China
Corresponding author’s signiture: Yuzhu Liu
1
Corresponding to author: Yuzhu Liu. E-mail: [email protected]
S0045-6535(19)32423-3
DOI:
https://doi.org/10.1016/j.chemosphere.2019.125184
Reference:
CHEM 125184
To appear in:
ECSN
Received Date: 12 July 2019 Revised Date:
13 October 2019
Accepted Date: 19 October 2019
Please cite this article as: Zhang, Q., Liu, Y., Yin, W., Yan, Y., Li, L., Xing, G., The in situ detection of smoking in public area by laser-induced breakdown spectroscopy, Chemosphere (2019), doi: https:// doi.org/10.1016/j.chemosphere.2019.125184. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2019 Published by Elsevier Ltd.
1
The in situ Detection of Smoking in Public Area by
2
Laser-induced Breakdown Spectroscopy
3
Qihang Zhang a, Yuzhu Liua,b,*, Wenyi Yina, Yihui Yana, Lei Lic and Guanhua Xingd
4 5 ， 7 8 9 10 11
a
Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing University of Information Science & Technology, Nanjing 210044, P. R. China b
Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology (CICAEET), Nanjing 210044, P. R. China
c
Institute of Mass Spectrometer and Atmospheric Environment, Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, P.R. China d
China National Environmental Monitoring Center, Beijing 100012, P. R. China
12
Abstract: The cigarette smoke in public area could be harmful to the non-smokers. In this paper,
13
laser-induced breakdown spectroscopy (LIBS) is applied to the in situ detection of the cigarette
14
smoke in public area, and the single particles aerosol mass spectrometer (SPAMS) is utilized to aid
15
the elemental analysis as well as realize the isotope detection. According to the obtained emission
1，
spectra, the smoke consists of Mg, Ca, Sr, Na, K elements which are absent in air, and the
17
concentrations of H2O and CO2 in smoke increase obviously. Moreover, the cigarette ash after
18
burning is taken as the sample for off-line detection and several heavy metal elements are detected.
19
The comparison between the spectra of cigarette smoke and ash shows that these two kinds of
20
detection are greatly different in terms of constituent and plasma status. In addition, the molecular
21
emission of Carbon-Nitrogen was observed in smoke spectrum, and the molecular vibrational and
22
rotational temperature of CN molecule was calculated. Finally, the LIBS and SPAMS were applied
23
to the semi-quantitative detection and isotope analysis of Pb in the smoke.
24
Keywords: Laser-induced breakdown spectroscopy, Single Particles Aerosol Mass Spectrometer,
25
in situ detection; smoke pollution; Pb
2， 27
1. Introduction
28
It is well-known that cigarette smoking is harmful for health due to the toxic ingredient of
29
cigarette. Moreover, the noxious smoke of the cigarette containing nicotine, tar, Pb, As and other
30
noxious ingredient also has pernicious effects on the non-smokers (Salvi et al.,2009). The research
31
also shows that the second-hand smoke could cause a wide range of adverse health effects,
32
including cancer, respiratory infections, heart attacks and other diseases (Glantz et al., 1991; Teo et
33
al., 2006; Öberg et al., 2011). Non-smokers exposed to second-hand smoke increase their heart
34
disease risk by 25–30% and their lung cancer risk by 20–30% (Barnoya et al., 2005).
*
Corresponding to author: Yuzhu Liu. E-mail: [email protected]
35
Accordingly, the smoking is strictly forbidden in most public area such as hospital, train
3，
station or office building all around the world with the purpose of eliminating such great damage
37
to the non-smokers. However, this significant prohibition is often ignored by some smokers, and
38
the smoke generated from their smoking could fill the whole of public area. Although the smoke
39
becomes thinner as time goes on, the damage still exists but the smell is no longer scented by the
40
non-smokers.
41
Therefore, it is of great significance to accurately evaluate the exposure to the cigarette
42
smoke of the people in the public area. While it is obviously not possible to adapt the method of
43
conventional chemical analysis because of their complicated procedure. Similarly, the present
44
optical methods such as atomic absorption spectrometry(AAS) (Dos Santos et al., 2017; Huang et
45
al., 2019), atomic fluorescence spectrometry(AFS) (Duan et al., 2017), and X-ray
4，
fluorescence(XRF) (Felix et al., 2018; Kapishnikov et al., 2017; Gama et al., 2017) also need
47
complex sample pretreatment or consume too much time. Therefore, it is not feasible to use these
48
methods for the in situ detection of smoking.
49
Laser-induced breakdown spectroscopy(LIBS) is an analytical method with many advantages
50
such as rapid and precise response, simultaneous multi-element analysis, high sensitivity (Viana et
51
al., 2019; Guo et al., 2017). Due to the merits above, it is widely applied to the component
52
analysis of coal, alloy and other inorganic substances (Rehan et al., 2018; Baudelet et al., 2010).
53
However, it could be troublesome to identify the spectral lines in LIBS spectrum when there exist
54
two or more possibilities. It is necessary to utilize other analytical method, such as mass spectrum,
55
to aid the analysis of LIBS. While the conventional mass spectrometer is not available to the in
5，
situ detection of cigarette smoke. Single particles aerosol mass spectrometer (SPAMS) has proven
57
to be a suitable method for the in situ component analysis in recent years (Li et al., 2016). It can be
58
applied to identify particle size and chemical composition from a single particle with extremely
59
high temporal and spatial resolution. Therefore, it could be an excellent choice to combine these
，0
two technique for the smoking detection.
，1
However, to our best knowledge, the in situ detection of the cigarette smoke by laser-induced
，2
breakdown spectroscopy combined with single particles aerosol mass spectrometer has never been
，3
addressed. In the present work, the LIBS and SPAMS were applied to the in situ detection of
，4
smoke in public area and the rapid evaluation of the exposure to cigarette smoke of the
，5
non-smokers.
，， ，7 ，8
2. Experimental section 2.1 LIBS setup
，9
The schematic diagram of the experimental setup is shown in Fig.1. The smoke is generated
70
from the burning cigarette. In order to realize the in situ detection, the laser pulse is directly
71
focused on the smoke, and the emission spectrum is obtained by the monitor(spectrometer). The
72
excitation laser employed in our work is a Q-switched Nd:YAG laser and it was operated at a
73
fundamental wavelength of 1064 nm; the energy is 260 mJ in a single laser pulse with a 6 ns
74
duration at a frequency of 10 Hz. The plasma radiation emission was directly collected by an
75
optical fiber coupled to a spectrometer with a spectral window ranging from 220 to 770 nm. The
7，
spectral resolution of the spectrometer is around 0.1 nm.
77 78 79
Fig.1 The schematic diagram of the experimental setup
2.2 SPAMS setup
80
The SPAMS setup has been introduced in detail in our previous paper (Li et al., 2011). The
81
single particles of the cigarette smoke in the size range of 0.1-2.0 µm were effectively drawn from
82
ambient atmosphere into the vacuum chamber, and then were gradually focused onto the axis of an
83
aerodynamic lens. The Nd:YAG laser (266 nm) employed as the excitation laser and the particles
84
were desorbed/ionized at the ion source region by the pulsed laser to get the mass spectrum, and
85
the energy of each pulse is approximately 520 µJ.
8， 87
3. Results and Discussion
88
3.1 The in situ elemental detection of smoke by LIBS
89
In order to simulate the detection in real environment condition, all the experiments in the
90
present work were operated in the air and the samples such as the cigarette smoke and ash were
91
detected by LIBS technique. Taking the cigarette smoke, ash as targets, the spectra of them were
92
obtained and analyzed, respectively.
93
The LIBS spectrum of cigarette smoke (labeled as Smoke On) were obtained and shown in
94
Fig.2. For comparison, the spectrum of the air without any cigarette smoke (labeled as Smoke Off)
95
was also put in the same figure. Before the analysis, to avoid the overlap of their spectral lines, the
9，
smoke spectrum was moved up in the direction of y-axis. The Fig.2 shows that the spectral lines in
97
the spectrum of cigarette smoke are much more than air spectrum. The observed spectral lines are
98
identified based on the NIST atomic spectra database and the results are marked in Fig.2
99
respectively. It can be found from the figure that the observed spectrum of the smoke consists of
100
the lines of C, Mg, Ca, Sr, Na, H, O, N, K, while only the lines of H, O, N elements can be
101
observed in the spectrum of air. In particular, the intensity of the Hα (656.28nm) line is much
102
lower than that in smoke’s spectrum, which can be explained by the lower concentration of H2O in
103
the air. Similarly, the C I (247.86nm) line in smoke’s spectrum is observed obviously while that in
104
air’s spectrum is too weak to be observed. Ca II 315.89nm Ca II 317.93nm 6000
4000
Smoke Off Smoke On
5000
3000
3000
2000
0
Mg II 279.55nm
-20
2000
2000
-40
Mg II 280.27nm
Sr II 407.77nm
-60
Sr I 421.55nm
-100
245 246 247 248 249 250
0
410
420
430
440
Hα 656.28nm
6000 2000
4000
O I 615.96nm
1000
Ca I 585.73nm
O I 715.67nm 2000
N I 746.831nm
Smoke Off Smoke On
1000
450
Wavelength/nm 6000
4000
K I 766.49nm K I 769.89nm
Na I 588.99nm Na I 589.59nm
Ca I 526.17nm Ca I 526.42nm Ca I 527.03nm
Ca I 559.01nm Ca I 559.45nm Ca I 559.85nm Ca I 560.13nm
3000
400
3000
Smoke Off Smoke On
Intensity/arb.units
340
N I 742.364nm N I 744.23nm
320
N I 665.28nm
300
Wavelength/nm
N I 672.48nm
280
N I 648.47nm
260
4000
2000
0 0
0 240
0 0
105 10， 107 108 109
500
1000
1000
Mg I 285.21nm
-80
1000
2000
C I 247.86nm
2000
Intensity/arb.units
3000
Ca I 422.67nm
4000
CaI: 428.30nm CaI: 428.94nm CaI: 429.90nm CaI: 430.25nm CaI: 430.77nm CaI: 431.87nm
Intensity/arb.units
4000
Intensity/arb.units
Smoke Off Smoke On
Ca I 442.54nm Ca I 445.59nm Ca I 443.49nm
6000
0 0
520
540
560
580
Wavelength/nm
600
600
620
640
660
680
700
720
740
760
780
Wavelength/nm
Fig.2 The LIBS spectra of air and cigarette smoke. (a)240-340nm, (b)400nm-450nm, (c)500nm-600nm, (d)600nm-780nm (left y-axis for smoke off, right y-axis for smoke on)
3.2 The spectra of cigarette smoke and ash
110
In this part, the cigarette ash after burning is taken as the sample for off-line detection by
111
LIBS technique in order to reveal the difference between the present detection with the off-line
112
detection. The spectra of smoke and ash ranged from 240nm to 780nm were shown as Fig.3. The
113
two spectra were merged in order to analyze the respective contents of cigarette smoke and ash as
114
well as the difference between them. The observed spectral lines in the spectra were also identified
115
according to the NIST database and the line information was added into the figure.
10000
2000
Mg I 285.21nm
4000
CN ∆ν=0
0 240
260
280
300
320
340
360
380
400
420
440
460
480
460
480
500
Ca I 487.81nm
Ca I 442.54nm Ca I 443.49nm Ca I 445.59nm
Ca I 422.67nm
Sr I 421.55nm
Sr II 407.77nm
Ca II 315.89nm Ca II 317.93nm
Ca II 393.37nm Ca II 396.85nm
2000
Mg I 382.94nm Mg I 383.23nm Mg I 383.83nm
Mg II 279.55nm
4000
Ca I 363.08nm Ca I 364.44nm
Ash
Ba I 493.41nm
6000
Mg II 280.27nm Mg I 285.21nm
Intensity/arb.units
Mg II 279.55nm Mg II 280.27nm
C I 247.86nm
6000
Ca II 393.37nm Ca II 396.85nm
Ca II 370.60nm Ca II 373.69nm
Ca II 315.89nm Ca II 317.93nm
Ca I 422.67nm
Smoke 8000
0 240
11，
260
280
300
320
340
360
380
400
420
440
500
8000 H 656.28nm
Smoke
α
N I 672.48nm
2000
N I 665.28nm
Ca I 559.01nm Ca I 559.45nm Ca I 559.85nm Ca I 560.13nm
4000
O I 715.37nm
0 740
760
K I 766.49nm K I 769.89nm
Ca I 672.08nm
720
Ca I 714.81nm
700
K I 693.88nm
680
K I 691.10nm
Ca I 647.17nm
660
Li I 670.77nm Ca I 671.77nm
2000
640 Ca I 646.26nm
Mg I 516.73nm Mg I 517.27nm Mg I 518.36nm
4000
620 Ca I 612.22nm
Ca II 645.69nm
Ca I 559.01nm Ca I 559.45nm Ca I 559.85nm Ca I 560.13nm
Ash 6000
600
Ca I 644.98nm
580
Ca I 643.91nm
560
Ca I 616.22nm Ca I 616.95nm
540
Ca I 610.27nm
520
Ca I 585.73nm Na I 588.99nm Na I 589.59nm
500 8000
Ca I:534.94nm
Intensity/arb.units
Ca I 585.73nm Na I 588.99nm Na I 589.59nm
6000
N I 742.36nm N I 744.23nm N I 746.83nm
Wavelength/nm
Ca I 732.39nm
0
117 118 119 120 121 122 123 124 125 12， 127 128 129 130 131 132 133
500
520
540
560
580
600
620
640
660
680
700
720
740
760
Wavelength/nm
Fig.3 The LIBS spectra of cigarette smoke and ash.
By comparing these two spectra, it was found that the spectral lines of Ca, Na, K and Mg were observed in both smoke’s spectrum and ash’s spectrum, indicating that these elements exist in smoke and ash, while the difference between these two spectra is significant. For instance, the C I (247.86nm), O I(715.37nm) and Hα (656.28nm) lines are completely invisible in ash’s spectrum, while these lines have high intensity in smoke’s spectrum. The burning of the cigarette makes C and H elements in the organics transfer to CO2, H2O, and they escape together with the smoke. Hence, there exists no C and H elements in the cigarette ash and their spectral lines are invisible in the spectrum. On the contrary, the spectral lines of several metal elements, such as Ba(493.41nm), Li(670.77nm), can only be observed in the spectrum of ash. Hence, there exists great difference between the constituents of cigarette smoke and ash. In addition, the comparison of the spectra above shows that, apart from the difference between the constituents of smoke and ash, there appears an interesting relationship between the intensities of ionic lines and atomic lines. Taking the spectral lines of Ca for instance, the atomic lines and ionic lines of Ca in the region from 365nm to 450nm are shown in Fig.4. It can be seen that the intensities of ionic lines (370.60nm, 373.69nm) in smoke are much higher than the
134 135 13，
intensities of Ca II lines in ash’s spectrum. Conversely, it is completely opposite in the case of atomic lines, the intensities of Ca I lines (430.25nm, 442.54nm, 443.49nm, 445.59nm, etc.) is far lower than those lines in ash’s spectrum. Similarly, the relationship between atomic lines and ionic
137
lines of Mg are the same as that of Ca as shown in Appendix(Fig.A.1). 6000
Smoke Ca I 428.30nm Ca I 428.94nm Ca I 429.90nm Ca I 430.25nm Ca I 430.77nm Ca I 431.87nm
Ca II 373.69nm
4000
Ca I 443.49nm Ca I 442.54nm Ca I 445.59nm
0 365
370
375
425
430
435
440
445
450
6000
Ash Ca I 428.30nm Ca I 428.94nm Ca I 429.90nm Ca I 430.25nm Ca I 430.77nm Ca I 431.87nm
Intensity/arb.units
Ca II 370.60nm
2000
4000
2000
Ca I 445.59nm Ca I 443.49nm Ca I 442.54nm
Ca II 370.60nm Ca II 373.69nm
0 365
138
370
375
425
430
435
440
445
450
Wavelength/nm
139
Fig.4 The atomic lines and ionic lines of Ca in the region from 365nm to 450nm
140 141 142 143 144 145 14， 147 148 149 150 151 152 153 154 155 15， 157 158 159
In consideration of the different matrix of these two samples, the matrix effect could be the primary cause accounting for this phenomenon. The matrix effect is of great significance to the LIBS detection and severely influences the accuracy of LIBS technique. It refers to the nonlinear laser-substance interaction in the process of laser ablation due to the difference in physical and chemical structure of the substance, which could lead to different spectral signals (Hahn et al., 2012). In this work, to be specific, the density of smoke is far lower than ash, which may cause higher temperature in smoke plasma. The extremely high temperature in the process of laser-matter interaction would make the atom ionize. The higher the plasma temperature is, the more likely the atoms are to ionize. Therefore, the intensity of ionic lines becomes higher with the increase of plasma temperature, while the intensity of atomic lines gets lower. To sum up the analysis and results, the on-line detection of smoke is quite different with the off-line detection of ash. 3.3 Molecular analysis of LIBS The LIBS technique is capable of elemental analysis as well as molecule analysis. In the present work, the LIBS technique was applied to the analysis of Carbon-Nitrogen free radical system. CN radical plays an important role in the combustion of carbides. In the outer layer of the plasma, the temperature is lower than the center, the molecular species could be direct released from the sample and combine with the molecular species in ambient atmosphere (Amiri et al., 2018). The formation of CN molecule can be elucidated by the reaction of carbon with atmospheric nitrogen (Kushwaha et al., 2008). In the most of cases, the CN emission band results
1，0 1，1 1，2 1，3 1，4 1，5 1，， 1，7 1，8 1，9 170 171 172 173 174 175 17， 177 178 179 180 181 182 183 184
from the recombination of C2 molecules released from aromatic rings and N2 molecules from air (St-Onge et al., 2002), where the C2 molecules being formed by recombination of carbon atoms and ions. However, as is shown in Fig.3, the C2 emission band (usually about 516.5nm) and the ionic lines of C element (usually about 426.7nm) are all absent in the spectrum of smoke. Therefore, the recombination of C2 molecules and N2 molecules could not be the explanation for the formation of CN molecules in this case, and there exists the other pathways. According to the literature (Lucena et al., 2011), it is likely that the CN molecules result from the direct reaction of C atoms from carbon dioxide or organic molecules and N atoms from air in the plasma. Hence, it is deduced that the CN emission band is intimately related to the organic constituent such as nicotine and benzopyrene in the smoke, and the analysis of CN radical is promising to be an effective method to detect the combustion of carbides in the air. The CN molecule emission band were observed in the spectrum of cigarette and shown in Fig.5. In order to accurately identify these lines, the CN molecule emission in air was simulated on LIFBASE, and the simulated emission band was also shown together with the experimental result. In addition, the CN emission band population distribution was shown in Appendix (Fig.A.2). The simulated result indicates that the emission band ranged from 375nm to 389nm generated by the B-X transition. And the intensities of the lines generated by the transition of the vibrational levels, which are distributed on the right of the band, are higher than those lines generated by the transition of the rotation levels. Hence, only the vibrational lines could be obviously distinguished, and the transition levels were identified and marked according to the simulated emission band. In addition, temperature is an important thermodynamic parameters and significant for studying the transitions of molecules and their chemical reactions. Hence, in this part, the vibrational temperature and rotational temperature are fitted on LIFBASE, and the result shows the vibrational and rotational temperatures are approximately 8000K and 7700K, respectively. 800
400
0-0 700
4-4 5-5 3-3
500
2-2
200
400
0
300 200
Intensity/arb.units
Intensity/arb.units
1-1
Exp Sim
600
-200
100 0
185 18， 187 188 189 190
376
378
380
382
384
386
388
-400 390
Wavelength/nm
Fig.5 The experimental and simulated emission band of CN
3.4 semi-quantitative detection and isotope analysis of Pb in smoke The experiment and analysis above preliminarily validate it achievable to qualitatively detect the ingredient of cigarette smoke in situ with LIBS method. However, the quantitative analysis of the toxic ingredient in smoke is essential as well as meaningful. In this part, we focused on Pb
191 192 193 194 195 19， 197 198 199 200 201
element due to its great damage on environment and human health. The cigarette samples to be measured were prepared by soaking them in the ሺܪܥଷ COOሻଶ Pb ∙ 3ܪଶ ܱ solution of different concentrations. The experiments were operated as before after the cigarettes were completely dried in the drying cabinet, and the spectra of these samples were obtained. Before the comparison, we normalized the spectra data by the intensity of the Ca II (396.85nm), which is close to the Pb I (405.78nm) line. Fig.6 shows the spectra in the region from 395nm to 450nm. As can be seen from the figure, there exists no signal of Pb I line when the Pb concentration equals to 0. While with the increase of the Pb concentration, the Pb I(405.78nm) appears and its intensity grows gradually. Therefore, it is deduced that the LIBS method in this work is promising to realize the quantitative analysis of Pb or other toxic ingredients in cigarette smoke in situ. Ca II 396.85nm
2.0 % 1.0 % 0.1 % 0.0 %
Pb I 405.78nm
Intensity/arb.units
Ca I 422.67nm
202 203 204 205 20， 207 208 209 210 211 212
400
410
420
430
440
450
Wavelength/nm
Fig.6 The variations of the spectral lines with the different concentration of Pb What’s more, as is well-known, there exist four isotopes (m/z=204,206,207,208) of Pb element. While it is impossible to detect the isotope of the single atom by LIBS technique. Hence, in order to analyze these isotopes of Pb, the smoke was also in situ detected by using a self-design Single Particles Aerosol Time of Flight Mass Spectrometer. The mass spectrometry can not only verify the result of the element analysis by LIBS, which is helpful for the identification of spectral lines, but also detect the abundance of the Pb in smoke samples. The mass spectrum of the isotope of Pb was shown as Fig.7. It is evident that the isotopes of Pb(206Pb+,207Pb+,208Pb+) can be obviously observed in the mass spectrum while the 204Pb cannot be observed for its low abundance in nature.
300
250
(53±4%)
200
208
+
Intensity/mV
Pb
150
(25±3%) 206
100
+ ±3%) Pb (22 207 + Pb
50
0 200
213 214 215 21， 217 218 219
201
202
203
204
205
206
207
208
209
210
M/Z
Fig.7 The mass spectrum of Pb isotope and abundance in the smoke Then the abundances of these three isotopes were calculated according to the intensities of peaks, and it shows that the abundance of Pb in smoke is similar to that in nature. However, it is well known that the isotopes obtained from different sources is likely to have different isotope ratios (Bol′shakov et al., 2015). Therefore, it can be deduced that the sources of the heavy mental elements can be determined according to the isotope abundance by using SPAMS.
220 221
Conclusion
222
In the present work, the LIBS was applied to the in situ detection of the cigarette smoke and
223
ash, and the SPAMS was used to aid the elemental analysis and realize the isotope detection of Pb
224
element. Based on the identification of the smoke spectrum, it can be found that the smoke from
225
burning consists of Ca, Na, Sr, K elements, which are nonexistent in the air. And the comparison
22，
with the air spectrum shows that the concentrations of the CO2 and H2O are much higher than
227
those in the air. In addition, the cigarette ash after burning is taken as the sample for off-line
228
detection, and then the ash spectrum is compared with smoke. It shows that there exists great
229
difference between the constituents of smoke and ash. The smoke spectrum contains spectral lines
230
of C, O, H elements while no Ba, Li lines exists, which can only be observed in the spectrum of
231
ash. Besides, the matrix effect of LIBS was also discussed by comparing the atomic lines and
232
ionic lines of Ca and Mg in cigarette smoke and ash. It shows that intensity of ionic line could be
233
higher in smoke than that in ash and the intensity of atomic lines could become lower because of
234
the high plasma temperature. Therefore, the results of on-line detection of smoke and off-line
235
detection of ash are greatly different. Moreover, the emission band of CN molecule in the region
23，
from 375nm to 389nm only appears in smoke spectrum, which is likely to generate from the direct
237
reaction of C atoms from carbon dioxide or organic molecules and N atoms from air in the plasma.
238
By simulated its emission band in LIFBASE, this band was identified and the vibrational and
239
rotational temperatures in our experiments are approximately 8000K and 7700K, respectively.
240
Then the Pb element in smoke was semi-quantitatively detected and the results shows that the with
241
the increase of the Pb concentration, the intensity of Pb I(405.78nm) grows gradually. Finally, the
242
Pb isotopes (206Pb,207Pb,
243
isotope was calculated. It is expected that LIBS combined with the SPAMS is promising to realize
244
the quantitative detection and source analysis of the toxic constituents in cigarette smoke in situ.
208
Pb) were in situ detected by the SPAMS, and the abundance of Pb
245 24，
Funding
247
National Key R&D Program of China (Grant No. 2017YFC0212700).
248 249
Acknowledgments
250
We would like to thank Miss Yuchen Hu for assisting in drawing Figure 1.
251 252
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1.The first study of the in situ detection of smoking in public area by LIBS and SPAMS. 2.The smoking was firstly detected by both on-line and off-line optical methods. 3.The CN band for cigarette was firstly studied by combining theory and experiment. 4.The self-designed SPAMS was applied to the isotope abundance analysis.
Dear editor, All the authors agree to submit this manuscript entitled “The in situ Detection of Smoking in Public Area by Laser-induced Breakdown Spectroscopy” to Chemosphere. All the authors declare that there is no conflict of interest. And I signed in the name of all the following authors for the agreement.
Qihang Zhang a, Yuzhu Liua,b,1, Wenyi Yina, Yihui Yana, Lei Lic and Guanhua Xingd a
Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing University of
Information Science & Technology, Nanjing 210044, P. R. China b
Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology
(CICAEET), Nanjing 210044, P. R. China c
Institute of Mass Spectrometer and Atmospheric Environment, Guangdong Provincial Engineering Research
Center for On-line Source Apportionment System of Air Pollution, Jinan University, Guangzhou 510632, P.R. China d
China National Environmental Monitoring Center, Beijing 100012, P. R. China
Corresponding author’s signiture: Yuzhu Liu
1
Corresponding to author: Yuzhu Liu. E-mail: [email protected]