Quantification of copper remediation in the Allium cepa L. leaves using electric field assisted laser induced breakdown spectroscopy

Journal Pre-proof Quantification of copper remediation in the Allium cepa L. leaves using electric field assisted laser induced breakdown spectroscopy

A. Jabbar, M. Akhtar, S. Mehmmod, M. Iqbal, R. Ahmed, M.A. Baig PII:

S0584-8547(19)30373-8

DOI:

https://doi.org/10.1016/j.sab.2019.105719

Reference:

SAB 105719

To appear in:

Spectrochimica Acta Part B: Atomic Spectroscopy

Received date:

7 August 2019

Revised date:

31 October 2019

Accepted date:

31 October 2019

Please cite this article as: A. Jabbar, M. Akhtar, S. Mehmmod, et al., Quantification of copper remediation in the Allium cepa L. leaves using electric field assisted laser induced breakdown spectroscopy, Spectrochimica Acta Part B: Atomic Spectroscopy(2018), https://doi.org/10.1016/j.sab.2019.105719

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© 2018 Published by Elsevier.

Journal Pre-proof

Quantification of Copper Remediation in the Allium Cepa L. leaves using Electric Field Assisted Laser Induced Breakdown Spectroscopy A. Jabbar1,2, M. Akhtar1,2, S. Mehmmod1, M. Iqbal3, R. Ahmed2 and M. A. Baig2,* [email protected], [email protected] 1

Department of Physics, Mirpur University of Science and Technology, 10250-Mirpur, AJK National Centre for Physics, Quaid-i-Azam University Campus, 45320- Islamabad, Pakistan 3 Environmental science, Faculty of Biological sciences, Quaid-i-Azam University, 45320 Islamabad, Pakistan

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Corresponding author.

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Abstract

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We present trace constituents of three plants of Onion (Allium Cepa L.), grown in the prepared soil containing varying concentration of copper under controlled environment to check its remediation capacity using Laser Induced Breakdown Spectroscopy (LIBS). The quantitative analysis of the samples was performed using Atomic Absorption Spectroscopy (AAS). The deduced concentration of copper was 0.05, 0.085 and 0.17 ppm for different leaves samples prepared with 10, 20 and 30 mg/L copper dose added in the germination soils through water. The limit of detection (LOD) of copper (Cu) in the samples has been improved to about 0.028 ppm using the electric field assisted LIBS technique.

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Keywords: LIBS, LOD, Cu. Plasma parameters, Emission Spectroscopy

Introduction Laser Induced Breakdown Spectroscopy (LIBS) is emerging as a powerful analytical technique which is mainly based on the analysis of the optical emission lines resulting from the laser ablation of any material. In LIBS, a high power laser beam is focused on the surface of a material which ablates its small amount and forms a plasma. The constituent elements of the material occupy excited states and subsequently de-excite by emitting radiations of particular wavelengths. The emitted radiation is collected and recorded using a high resolution spectrometer for subsequent detection/analysis of the elements present in the sample [1, 2]. LIBS

Journal Pre-proof is a fast growing technique used for the analysis of plant samples [3-8]. Numerous books have been published during the last couple of decades on the application of LIBS describing the potential use of LIBS in determining the trace elements from the organic samples [9-11]. LIBS has been used as an analytical technique for the direct elemental analysis of micro, macro nutrient elements and heavy metals in food and plant samples [3]. Senesi et al [12] determined the elemental composition from the composts and plants using LIBS and compared the results with that of Inductively Coupled Plasma Optical Emission Spectrometry (ICP- OES) and

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inferred that LIBS is a compatible analytical technique to the standard techniques. Galiova et al [13] detected the heavy metals in plants using LIBS and Laser Ablation Inductively Couples

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Plasma Mass Spectrometry (LA-ICP-MS). LIBS has been used to detect the trace elements in plants, materials and determined the LOD of toxic metals in aqueous solution in the range of

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0.029-0.59 ppm [14]. The LOD of trace elements was reported as 2.2 ppm for B, 3.0 ppm for

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Cu, 3.6 ppm for Fe , 1.8 ppm for Mn and 1.2 ppm for Zn [15]. Arantes et al [16] reported the LOD of macro and micronutrients in plants samples using femtosecond LIBS and nanosecond

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LIBS. For Cu, the LOD was about 7, 1 and 3 ppm in the case of fs-LIBS and ns-LIBS at 1064 and 532 nm respectively. The use of of Cu and Zn in excessive amounts in food items and plants

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may results as phytotoxicity. Borkert et al. [17] reported the Zn and Cu toxicity in rice, corn, peanut and soybean. Common toxic metals which are hazardous for biosphere are Hg, Pb, Cd,

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Cu, Cr, Mn, Zn, and Al [18].

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The analytical determination of trace elements in plants or animal samples has always been a challenge for researchers. Therefore, a number of analytical techniques have been tried for the detection and analysis of the trace elements in organic samples. Besides much advancements in research, this problem is still under extensive investigations. In recent years, remarkable interest has been developed for the enhancement of LIBS signals by different techniques such as dual pulse LIBS [19], Spatial [20], Magnetic confinement [21-24], electric or spark discharge enhancement [5, 25, 26], resonance enhanced LIBS [27], cavity confinement [28], shock waves [29], nanoparticle enhanced LIBS [30, 31] and other methods [32-35]. However, a number of experiments reveal that the spark discharge or electric field assisted LIBS is an effective approach to improve the analytical performance of LIBS [25, 36, 37]. Recently Li et al. [38] reviewed the signal enhancement methods including spark discharged LIBS.

Journal Pre-proof The quantitative analysis can be performed using LIBS and the most accepted procedure to determine the composition of sample is by using the calibration curves. However, the calibration standards for a number of environmental samples are not available. To address this issue, Ciucci et al. [39] described the calibration free LIBS technique (CF-LIBS) in which the calibration curves are not required. This method is based on certain assumptions; (i) the plasma is optically thin (ii) in local thermal equilibrium (LTE) and (iii) stoichiometric ablations [40]. The added excitation source with the traditional LIBS improves the signal to noise ratio (S/N) and minimizes the self-absorption contribution. Recently, it has been reported that the CF-LIBS

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sensitivity can be improved by recording the emission spectra with shorter and longer delays to

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quantify major, minor and trace elements from the organic materials [41]. In the present work, we have applied the electric field assisted LIBS on the Allium Cepa L. leaves to improve the

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limit of detection of Cu. The LOD of Cu has also been improved by using the electric field assisted LIBS which has several advantages like multi-element detection and fast analysis

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technique as compared with the other conventional analytical techniques.

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Material and methods

Seed sowing: Seeds of Allium Cepa L. were collected from the local market and sown in the peat

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moss. After a week, the seedling was germinated that were allowed to grow further in the same

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soil for five weeks and then were provided by the tap water. Transferring of seedlings in to soil/sand mixture: After five weeks, each seedling was

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transferred into a separate pot containing a mixture of soil and sand with 3:1 ratio. Total sixteen pots were prepared, out of which each group of pots belongs to a common concentration of heavy metal provided and within the group each pot was denoted as replicate. Watering: For the initial time period of one week, the pots were watered by tap water, and later the pots were watered by the CuSO4 solution at different concentrations. Each group of four replicates were provided the following Cu concentrations; 0, 10, 20 and 30 mg L-1 for three weeks. Harvesting: After completing the stress providing period, the plants were harvested, and were projected to get dried in a dry oven at 70 0C for 72 Hrs. As soon as the plants got dried, they were crushed in to fine powder. Then sample size of 0.1 g (crushed powder) was separated from

Journal Pre-proof each plant and was acid digested by Aqua Regia on hot plate. The volume of the digest rate from each sample was raised up to 25 ml by adding distilled water in it. Experimental set up: For the LIBS analysis, the leaves were dried, grinded and pressed into pellets of diameter 1.2 cm and 2 mm thickness. For the AAS analysis, powdered samples were acid digested and then inserted to AAS in the liquid form. A schematics of the experimental setup is shown in Fig. 1. The procedure for the laser produced plasma studies of these samples is the same as described in

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our earlier publications [5, 21].

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Fig. 1: Schematic illustration of the LIBS Setup

A Q-switched Nd:YAG laser (Quantal, Brilliant B), capable of delivering about 500 mJ at 532 nm, 5 ns pulse duration and 10 Hz repetition rate was used to produce plasma at the surface of the sample. The laser beam was focused on the target surface using a 10 cm focal length quartz lens and the diameter of the focused laser beam was about 1 mm. During the experimentation, the laser pulse energy was measured by an energy meter (Nova-Quantal). To avoid the deep craters, the target was constantly rotated. In order to avoid the breakdown of the air in front of a sample, the lens to sample distance was kept less than the focal length of the lens. The plasma radiation was collected by optical fiber (core diameter of 600 µm) with a collimating lens (0– 450) which was placed perpendicular to the laser beam. The collected radiation was transferred to the detection system and detected through software (Avasoft 8.0). The detection system contains

Journal Pre-proof 4 spectrometers, each equipped with 10 µm slit width, charged coupled device (CCD) detectors and covers the wavelength range of 250 – 870 nm (Avantes: The Netherlands). The integration time of the spectrometer was adjusted at 1 ms and all the emission spectra were registered at the time delay of 2 µs after the plasma generating laser pulse. The instrumental width was measured as 0.06 nm at 500 nm using a narrow bandwidth dye laser. To correct the emission signal, the dark signal of the detector was subtracted through the software. To enhance the emission signals, an external electric field (100 Volts/mm) was applied across the two electrodes. The two rectangle shaped Aluminum plates (1cm x 1cm in size and 3 mm apart) were used for applying

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the electric field. The laser beam was focused on the sample surface placed at the middle of the

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two electrodes and the detector was positioned perpendicular to the focused laser beam. The two plates were connected to a regulated DC power supply. The field strength of the electrical

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breakdown in air is about 3 kV/mm, which is much higher than the applied electric field (≤ 100 V/mm). The ablation of the sample by the laser induced plasma also triggered the discharge

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between the electrodes. In addition, the concentration of Cu in the samples were determined by

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the standard atomic absorption technique (AAS) using Acetylene flame atomic absorption spectroscope. The pressure of acetylene flame was set to >700 kPa (~100 psi), the acetylene

Results and Discussions:

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valve was set to 11 psi, and the air valve was adjusted at 45 psi.

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The laser produced plasma on the surface of the samples having variable copper concentrations of 0, 10, 20 and 30 mg L-1 in the germination soil were studied by LIBS at about 25 J/cm2 laser

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fluence and the time delay between the laser pulse and the detection system was 2 µs. The experiments were repeated under identical experimental conditions using LIBS but the samples were placed in an external electric field, 100 V/mm. All the spectra were recorded at an average of 10 laser shots at different sites of the samples placed in air at atmospheric pressure. Fig. 2 (a) shows the emission spectra of all the three samples, having variable copper concentrations, without the external electric field. The spectral lines of calcium and magnesium are dominant. The structure around 526 nm belongs to Ca I 3d4p 3P0,1,2 → 3d4s 3D1,2,3 transitions and the triplet structure at 516.73 nm, 517.26 nm and 518. 36 nm belongs to Mg I 3s4s 3S1 → 3s 3p 3P0, 1, 2 transitions. The adjacent line at 518.84 nm is identified as Ca I 4s5d 1D2 → 4s4p 1P1 transition. The line at 373.69 nm corresponds to singly ionized calcium 5s 2S1/2 → 4p 2P3/2 transition. The lines were identified using the NIST database [42]. These identified elements are micronutrients

Journal Pre-proof which are very important for the plant growth and other mechanisms. In these spectra, not a single line of the added copper impurity has been detected. In Fig.2 (b), we show the emission spectra of the same samples, recorded in the presence of an external electric field of 100 V/mm, while all the other experimental parameters were kept the same. Evidently, numerous additional lines appear in the spectra. The resonance lines of copper (4p 2P3/2,1/2 → 4s 2S1/2) at 324.75 nm and 327.39 nm appear with good intensities. The lines at 521.82 nm, 515.32 nm due to the 4d 2

D5/2,3/2 → 4p 2P1/2,3/2 transitions and the line at 510.55 nm is due to the 4p 2P3/2 → 3d9 4s2 2D5/2

transition in copper. A singly ionized aluminum line is also observed at 358.66 nm. All the

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copper lines gain intensity as the copper concentration is increased. In addition, the intensities of

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the calcium and magnesium lines also increase as the copper concentration increases. Thus, applying electric field as an additional excitation source, numerous additional emission lines

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appear with better signal to noise ratio. The enhancement in the line intensities in the presence of external electric field is explained as follows. Plasma is produced between the two electrodes,

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once a laser beam is focused on the surface of sample. The distance between the electrodes is

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comparable to the dimensions of the plasma. As a result, the plasma touches the electrodes and a very high current flows between the electrodes through the plasma producing a spark. This spark

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reheats the plasma and hence the rates of recombination and collision excitation and ionization increases which also increases the emission intensities. In particular, the cold region around the hot ionized plasma is also energized by providing an additional energy. Thus, the layer of the

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cold region around the hot ionized plasma is also reduced under these conditions leading to the

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enhanced (self-absorption free) emission of the neutral lines.

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Fig. 2: Emission spectra of Allium Cepa L. leaves having 10, 20 and 30 mg L-1 added dose of Cu in the germination soil (a) without Electric field (b) with electric field. A comparison of the Ca and Mg line intensities in Fig.2 (a, b) reveals nearly 3-fold intensities enhancement in the presence of electric field. Much better signal to noise ratios (S/N) have been observed, nearly 10 in all the three sample with different copper concentrations. The S/N ratio is calculated by the following formula: 𝑆 𝑁

𝐼

=𝜎

(1)

Journal Pre-proof Where, I is the intensity of the spectral line and σ is the standard deviation calculated from the background in the vicinity of the line. In the 10 mg L-1 Cu added to the Allium cepa L. leaves sample, we observed only two lines of Cu while in the 20 mg L-1 added Cu sample, five lines of Cu I at 324.75 nm, 327.39 nm and 510.55 nm, 515.32 nm and 521.82 nm are observed. The intensities of these lines increase with the increase of the copper concentration. The other detected lines belong to different elements; Ca, Si, Mg, K, Na, Cu, N, O and H. Nitrogen and oxygen lines are although common elements in plants but as the experiments were performed in

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air therefore, their emission lines appear due to the surrounding moisture.

Fig. 3: Comparison of the line intensities of the Cu resonance lines in the three samples with varying copper concentrations in the germination soil. In Fig.3, we present the spectra of the samples with different concentrations of copper in the germination soil, 10 mg L-1. 20 mg L-1 and 30 mg L-1, recorded in the presence of electric field covering the wavelength region from 320 nm to 328 nm. The copper resonance lines at 324.75 nm and 327.39 nm are evident and their intensities increase as the copper concentration in the samples increases. It is worth to mention that these lines were too weak to be detected in the spectra registered in the absence of electric field (see Fig.2 a), the laser energy and other

Journal Pre-proof parameters were kept the same in both the experiments. Evidently, the emission intensity enhancement seems to be purely electric field dependent which is attributed to the energy deposition in the spark discharge that increases the collisional rates of the ablated species. Naseef and Elsayed-Ali [25] combined LIBS with spark discharge and applied to Al and Cu targets places in air at atmospheric pressure and reported significant lines intensity enhancements in Al and Cu lines. Hou et al [26] inferred that the spark discharge is an effective way for the signal enhancement in the Coal samples. To confirm that the plasma is optically thin, we compared the observed lines intensities ratio of

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various lines of different elements with their ratio of their transition probabilities [43]. The

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calculated ratio for the spectral lines of copper at 324.75 nm and 327.39 nm is 2.18 while the experimental value is 2.24 which differs only by 3% and supports our assertion that the plasma is

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optically thin and the lines are free from self-absorption. For the calculation of the electron temperature, we have used the Boltzmann plot method [44]. To draw the Boltzmann plot and to

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determine the excitation temperature, only those calcium lines were selected that fulfil certain

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crucial criteria [45]. The spectroscopic parameters of these lines are tabulated in Table-1. The Boltzmann plot based on the spectra taken in the presence and absence of E-field are displayed in

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Fig. 3. The values of the plasma temperatures in the 10 ppm sample is 7650 K, for the 20 ppm sample is 6500 K and for the 30 ppm sample is 7300 K in the presence of electric field while in the absence of electric field, the temperature values are 6500 K, 5500 K and 6900 K respectively.

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Evidently, the plasma temperature increases in the electric field assisted LIBS, about 10%, which

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may be attributed to reheating of the preexisting plasma in the presence of electric field. Moreover, it is also evident from the linearity of the Boltzmann plot that the lines possess good S/N ratio and are free from self-absorption effect.

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Fig. 4: Boltzmann Plot for the Ca I lines of the 20 mg L-1 sample. Table 1. Calcium lines used for to draw the Boltzmann Plot Upper Level

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Wavelength

Transition Probability A (s-1)

38551.55

5

4.34E+07

42919.05

5

4.00+07

526.55

39335.32

3

4.40E+07

559.01

38219.11

5

8.3E+06

559.84

38192.39

3

4.30E+07

560.28

38192.39

3

1.40E+07

610.27

31539.49

3

4.77E+07

643.90

35896.9

9

5.30E+07

387.57

46164.9

9

7.9E+6

422.67 518.88

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gk

λ (nm)

Energy Ek (cm-1)

Statistical Weight

Journal Pre-proof The electron density Ne was calculated from the Stark broadened line profile of Ca observed at 445.47 nm in the presence and absence of electric field. The full width at half maximum (FWHM) was determined by the Lorentzian profile fit to the Stark broadened spectral line of calcium at 445.47 nm. The FWHM was corrected by taking into account the instrumental width (0.06 nm) using the following relation [46]: ∆ 𝜆𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 = (

∆𝜆𝑆𝑡𝑎𝑟𝑘 2

∆𝜆𝑆𝑡𝑎𝑟𝑘 2

) + √⌊(

2

) + (∆ 𝜆𝐼𝑛𝑠𝑡𝑟𝑢𝑚𝑒𝑛𝑡𝑎𝑙 )2 ⌋

(2)

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Where ∆ 𝜆𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 is the measured FWHM from the observed line profile, ∆ 𝜆𝑆𝑡𝑎𝑟𝑘 is the true width of the Stark broadened line and ∆ 𝜆𝐼𝑛𝑠𝑡𝑟𝑢𝑚𝑒𝑛𝑡𝑎𝑙 is the instrumental broadening. The 𝑁

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FWHM of a Stark broadened profile is related with the electron density as [47]: (3)

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𝑒 ∆𝜆𝑆𝑡𝑎𝑟𝑘 = 2𝜔 (1016 )

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Where Ne is the electron density and ω is the electron impact parameter, listed by Griem [43]. The electron density is calculated as (5.0 ± 0.5) ×1016 cm-3 for the 10 ppm copper added sample

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without the applied electric field. The electron density calculated from the spectra taken in the presence of electric field increased to (7.1 ± 0.5) × 1016 cm-3. Similarly, for the 20 ppm and 30

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ppm Cu added samples, the electron densities in the absence of electric field are (5.5 ± 0.5) ×1016 cm-3 and (6.8 ± 0.5) × 1016 cm-3 that increase to (6.3 ± 0.5) ×1016 cm-3 and (7.1 ± 0.5) ×1016 cm-3

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respectively in the presence of electric field.

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Fig. 4: Stark Broadened profiles of the Ca-I line at 445.47 nm along with the Voigt Fit to the experimental data point acquired in the absence and presence of electric field. The validation of the local thermodynamic equilibrium (LTE) condition was achieved for all the

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three samples by using the McWhirter’s criteria [48]: 1

(4)

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𝑁𝑒 ≥ 1.6 × 1012 𝑇 2 (∆𝐸)3

Where Ne is the electron density (cm-3), ∆E(eV) is the difference between upper and lower level energy and T(K) is the excitation temperature. The minimum electron density required to satisfy the LTE criteria is about 1015 cm-3. The electron densities calculated from the Stark broadened line profile of calcium at 445.47 nm is much higher than that required to satisfy the LTE condition. As the plants were grown under controlled environment and with known copper concentrations in the water added to the germination soil therefore, to determine the copper concentrations in the leaves of the samples via remediation, we used the standard Atomic Absorption Spectroscopy (AAS). The copper concentration in the leaves samples have been determined as 0.05 mg L-1,

Journal Pre-proof 0.085 mg L-1 and 0.17 mg L-1 corresponding to 10, 20 and 30 mgL-1 copper concentrations added in the germination soils through water. In Fig.5, we present a calibration curve in which the intensities of all the copper lines in the three samples are drawn against the concentration of Cu in the leaves determined by the AAS in the three samples. Each point in the calibration curve is the mean value obtained from 5 replicate measurements. The linear regression fitting to the experimental data point shows a good linearity factor (R2 = 0.994). The LOD is determined by using the equation: 3𝜎

(5)

𝑏

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𝐿𝑂𝐷 =

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Where σ is the standard deviation of the background and b is the slope of the curve. Using the

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above relation, we have calculated the limit of detection from the Cu line at 324.75 nm as 0.028 mg L-1, which is much improved from the values reported in the literature [15, 16]. A possible

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reason for this improved LOD is attributed to the improved S/N ratio in the presence of electric

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field assisted LIBS.

Fig. 5: Calibration curve to calculate the LOD of Cu

Journal Pre-proof Conclusion We have presented LIBS studies of the Allium cepa L. leaves to detect its remediation capacity of up-taking copper from the plants germinated under controlled environment and controlled copper concentration in the soil. The copper lines that were too weak to be detected in the spectra taken in the absence of electric field emerged strongly in the presence of an external E-field. The electric field assisted LIBS yields signal enhancement along with an increase in the plasma temperature and electron density. The reheating of the plasma in the presence of electric field is

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responsible for the increase in the emission intensity enhancement, plasma temperature and electron number density. The limit of detection of Cu has been improved to 0.028 mg L-1. It is

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trace, minor and toxic elements can be improved.

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concluded that using electric field as an added excitation source, the limit of detection of the

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Acknowledgement

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We are grateful to the Pakistan Academy of Sciences (PAS) and National Centre for Physics (NCP) for the financial assistance to acquire the necessary laboratory equipment.

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References

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[1] J.P. Singh, S.N. Thakur, Laser-induced breakdown spectroscopy, Elsevier, 2007. [2] D. A. Cremers, L. J. Radziemski, Handbook of Laser-Induced Breakdown Spectroscopy: Second Edition, 2013. [3] D. Santos Jr, L.C. Nunes, G.G.A. de Carvalho, M. da Silva Gomes, P.F. de Souza, F. de Oliveira Leme, L.G.C. dos Santos, F.J. Krug, Laser-induced breakdown spectroscopy for analysis of plant materials: a review, Spectrochim. Acta B, 71 (2012) 3-13. [4] A. Jabbar, M. Akhtar, A. Ali, S. Mehmood, S. Iftikhar, M.A. Baig, Elemental composition of rice using calibration free laser induced breakdown spectroscopy, Optoelectronics Letters, 15 (2019) 57-63. [5] A. Jabbar, M. Akhtar, S. Mehmood, A. Nasar, Z.A. Umar, R. Ahmed, M.A. Baig, On the Detection of Heavy Elements in the Euphorbia Indica Plant Using Laser Induced Breakdown Spectroscopy and Laser Ablation Time of Flight Mass Spectrometry, Journal of Analytical Atomic Spectrometry, (2019). [6] P.F. de Souza, D.S. Júnior, G.G.A. de Carvalho, L.C. Nunes, M. da Silva Gomes, M.B.B. Guerra, F.J. Krug, Determination of silicon in plant materials by laser-induced breakdown spectroscopy, Spectrochim. Acta B, 83 (2013) 61-65. [7] M. da Silva Gomes, G.G.A. de Carvalho, D.S. Junior, F.J. Krug, A novel strategy for preparing calibration standards for the analysis of plant materials by laser-induced breakdown spectroscopy: A case study with pellets of sugar cane leaves, Spectrochim. Acta B, 86 (2013) 137-141.

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[8] G.G. Arantes de Carvalho, M.B. Bueno Guerra, A. Adame, C.S. Nomura, P.V. Oliveira, H.W. Pereira de Carvalho, D. Santos, L.C. Nunes, F.J. Krug, Recent advances in LIBS and XRF for the analysis of plants, Journal of Analytical Atomic Spectrometry, 33 (2018) 919-944. [9] D. Hahn, N. Omenetto, Laser-Induced Breakdown Spectroscopy (LIBS), Part II: Review of Instrumental and Methodological Approaches to Material Analysis and Applications to Different Fields, 2012. [10] R. Noll, Laser-induced breakdown spectroscopy, in: Laser-Induced Breakdown Spectroscopy, Springer, 2012, pp. 7-15. [11] D.A. Cremers, F.Y. Yueh, J.P. Singh, H. Zhang, Laser‐ induced breakdown spectroscopy, elemental analysis, Encyclopedia of Analytical Chemistry: Applications, Theory and Instrumentation, (2006). [12] G.S. Senesi, M. Dell'Aglio, A. De Giacomo, O. De Pascale, Z.A. Chami, T.M. Miano, C. Zaccone, Elemental Composition Analysis of Plants and Composts Used for Soil Remediation by Laser‐ Induced Breakdown Spectroscopy, Clean–Soil, Air, Water, 42 (2014) 791-798. [13] M. Galiova, J. Kaiser, K. Novotný, J. Novotný, T. Vaculovič, M. Liška, R. Malina, K. Stejskal, V. Adam, R. Kizek, Investigation of heavy-metal accumulation in selected plant samples using laser induced breakdown spectroscopy and laser ablation inductively coupled plasma mass spectrometry, Applied Physics A, 93 (2008) 917-922. [14] Z. Chen, H. Li, M. Liu, R. Li, Fast and sensitive trace metal analysis in aqueous solutions by laser-induced breakdown spectroscopy using wood slice substrates, Spectrochim. Acta B, 63 (2008) 64-68. [15] L.C. Trevizan, D. Santos Jr, R.E. Samad, N.D. Vieira Jr, L.C. Nunes, I.A. Rufini, F.J. Krug, Evaluation of laser induced breakdown spectroscopy for the determination of micronutrients in plant materials, Spectrochim. Acta B, 64 (2009) 369-377. [16] G.G. Arantes de Carvalho, J. Moros, D. Santos, F.J. Krug, J.J. Laserna, Direct determination of the nutrient profile in plant materials by femtosecond laser-induced breakdown spectroscopy, Analytica Chimica Acta, 876 (2015) 26-38. [17] C. Borkert, F. Cox, M. Tucker, Zinc and copper toxicity in peanut, soybean, rice, and corn in soil mixtures, Communications in soil science and plant analysis, 29 (1998) 2991-3005. [18] Y. Omura, Y. Shimotsuura, A. Fukuoka, H. Fukuoka, T. Nomoto, Significant mercury deposits in internal organs following the removal of dental amalgam, & development of precancer on the gingiva and the sides of the tongue and their represented organs as a result of inadvertent exposure to strong curing light (used to solidify synthetic dental filling material) & effective treatment: a clinical case report, along with organ representation areas for each tooth, Acupuncture & electro-therapeutics research, 21 (1996) 133-160. [19] A. Zakuskin, A. Popov, S. Zaytsev, N. Zorov, M. Belkov, T. Labutin, Orthogonal and Collinear Configurations in Double-Pulse Laser-Induced Breakdown Spectrometry to Improve Sensitivity in Chlorine Determination, Journal of Applied Spectroscopy, 84 (2017) 319-323. [20] A.M. Popov, F. Colao, R. Fantoni, Enhancement of LIBS signal by spatially confining the laser-induced plasma, Journal of Analytical Atomic Spectrometry, 24 (2009) 602-604. [21] M. Akhtar, A. Jabbar, S. Mehmood, N. Ahmed, R. Ahmed, M.A. Baig, Magnetic field enhanced detection of heavy metals in soil using laser induced breakdown spectroscopy, Spectrochim. Acta B, 148 (2018) 143-151. [22] L. Guo, W. Hu, B. Zhang, X. He, C. Li, Y. Zhou, Z. Cai, X. Zeng, Y. Lu, Enhancement of optical emission from laser-induced plasmas by combined spatial and magnetic confinement, Optics express, 19 (2011) 14067-14075.

Journal Pre-proof

Jo

ur

na

lP

re

-p

ro

of

[23] V.N. Rai, H. Zhang, F.Y. Yueh, J.P. Singh, A. Kumar, Effect of steady magnetic field on laser-induced breakdown spectroscopy, Applied Optics, 42 (2003) 3662-3669. [24] X.K. Shen, Y.F. Lu, T. Gebre, H. Ling, Y.X. Han, Optical emission in magnetically confined laser-induced breakdown spectroscopy, Journal of Applied Physics, 100 (2006) 053303. [25] O.A. Nassef, H.E. Elsayed-Ali, Spark discharge assisted laser induced breakdown spectroscopy, Spectrochim. Acta B, 60 (2005) 1564-1572. [26] Z. Hou, Z. Wang, J. Liu, W. Ni, Z. Li, Combination of cylindrical confinement and spark discharge for signal improvement using laser induced breakdown spectroscopy, Optics express, 22 (2014) 12909-12914. [27] T. Ohta, M. Ito, T. Kotani, T. Hattori, Emission enhancement of laser-induced breakdown spectroscopy by localized surface plasmon resonance for analyzing plant nutrients, Applied spectroscopy, 63 (2009) 555-558. [28] R. Ahmed, M. Akthar, A. Jabbar, Z. Umar, N. Ahmed, J. Iqbal, M. Baig, Signal Intensity Enhancement by Cavity Confinement of Laser-Produced Plasma, IEEE Trans. Plasma. Sci., 47 (2019) 1616-1620. [29] A. Zakuskin, A. Popov, N. Zorov, T. Labutin, Confinement of Laser Plasma by Shock Waves for Increasing Signal Intensity in Spectrochemical Determination of Trace Elements in Ores, Technical Physics Letters, 44 (2018) 73-76. [30] A. De Giacomo, M. Dell'Aglio, R. Gaudiuso, C. Koral, G. Valenza, Perspective on the use of nanoparticles to improve LIBS analytical performance: nanoparticle enhanced laser induced breakdown spectroscopy (NELIBS), Journal of Analytical Atomic Spectrometry, 31 (2016) 1566-1573. [31] M. Dell'Aglio, Z. Salajková, A. Mallardi, R. Mezzenga, L. van't Hag, N. Cioffi, G. Palazzo, A. De Giacomo, Application of gold nanoparticles embedded in the amyloids fibrils as enhancers in the laser induced breakdown spectroscopy for the metal quantification in microdroplets, Spectrochim. Acta B, 155 (2019) 115-122. [32] Y. Wang, H. Yuan, Y. Fu, Z. Wang, Experimental and computational investigation of confined laser-induced breakdown spectroscopy, Spectrochim. Acta B, 126 (2016) 44-52. [33] Y. Fu, Z. Hou, Z. Wang, Physical insights of cavity confinement enhancing effect in laserinduced breakdown spectroscopy, Optics express, 24 (2016) 3055-3066. [34] H. Yin, Z. Hou, T. Yuan, Z. Wang, W. Ni, Z. Li, Application of spatial confinement for gas analysis using laser-induced breakdown spectroscopy to improve signal stability, Journal of Analytical Atomic Spectrometry, 30 (2015) 922-928. [35] S. Zhang, S. Sheta, Z.-Y. Hou, Z. Wang, On the improvement of signal repeatability in laser-induced air plasmas, Frontiers of Physics, 13 (2018) 135201. [36] K. Li, W. Zhou, Q. Shen, Z. Ren, B. Peng, Laser ablation assisted spark induced breakdown spectroscopy on soil samples, Journal of Analytical Atomic Spectrometry, 25 (2010) 1475-1481. [37] P. Liu, J. Liu, D. Wu, L. Sun, R. Hai, H. Ding, Study of Spark Discharge Assisted to Enhancement of Laser-Induced Breakdown Spectroscopic Detection for Metal Materials, Plasma Chem. Plasma Process., 38 (2018) 803-816. [38] Y. Li, D. Tian, Y. Ding, G. Yang, K. Liu, C. Wang, X. Han, A review of laser-induced breakdown spectroscopy signal enhancement, Applied Spectroscopy Reviews, 53 (2018) 1-35. [39] A. Ciucci, M. Corsi, V. Palleschi, S. Rastelli, A. Salvetti, E. Tognoni, New Procedure for Quantitative Elemental Analysis by Laser-Induced Plasma Spectroscopy, Applied Spectroscopy, 53 (1999) 960-964.

Journal Pre-proof

Jo

ur

na

lP

re

-p

ro

of

[40] S. Pandhija, A. Rai, In situ multielemental monitoring in coral skeleton by CF-LIBS, Applied Physics B, 94 (2009) 545-552. [41] C.-T. Chen, D. Banaru, T. Sarnet, J. Hermann, Two-step procedure for trace element analysis in food via calibration-free laser-induced breakdown spectroscopy, Spectrochim. Acta B, 150 (2018) 77-85. [42] Y. Ralchenko, NIST atomic spectra database, 2005. [43] V.K. Unnikrishnan, K. Mridul, R. Nayak, K. Alti, V.B. Kartha, C. Santosh, G.P. Gupta, B.M. Suri, Calibration-free laser-induced breakdown spectroscopy for quantitative elemental analysis of materials, Pramana, 79 (2012) 299-310. [44] J. Aguilera, C. Aragón, Multi-element Saha–Boltzmann and Boltzmann plots in laserinduced plasmas, Spectrochim. Acta B, 62 (2007) 378-385. [45] A. De Giacomo, M. Dell'Aglio, O. De Pascale, S. Longo, M. Capitelli, Laser induced breakdown spectroscopy on meteorites, Spectrochim. Acta B, 62 (2007) 1606-1611. [46] D.W. Hahn, N. Omenetto, Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma–Particle Interactions: Still-Challenging Issues Within the Analytical Plasma Community, Appl. Spectrosc. 64 (2010) 335A [47] N. Konjević, A. Lesage, J.R. Fuhr, W.L. Wiese, Experimental Stark Widths and Shifts for Spectral Lines of Neutral and Ionized Atoms (A Critical Review of Selected Data for the Period 1989 Through 2000), J. Phys. Chem. Ref. Data, 31 (2002) 819-927. [48] R.W.P. McWhirter, Plasma Diagnostic Techniques (Pure and Applied Physics), 21 (1965) 201-264.

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Highlights  

Quantification of Remediation of copper in the Allium Cepa L. leaves grown under controlled environment using LIBS Signal Enhancement by Electric Field Assisted Laser Induced Breakdown Spectroscopy

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 Trace Elemental Detection and improved copper Limit of Detection Graphical abstract