|
|
|
| Analysis of Trace Metal Elements in Water Based on Discharge-Assisted Laser-Induced Breakdown Spectroscopy |
| Xu Boping1,2, Liu Yinghua1,2, Liu Zaihao1,2, Yin Peiqi1,2, Tang Jie1,2 |
1. State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics of CAS Xi'an 710119 China;
2. University of Chinese Academy of Sciences Beijing 100049 China |
|
|
|
Abstract Heavy metal ion-induced water pollution has become a severe environment in the world. Laser-induced breakdown spectroscopy (LIBS) is a novel analytical technique based on the atomic emission spectroscopy, which can be used for the target in any state. Thus, LIBS is widely applied in various applications, including environmental pollution monitoring, food safety, and chemical engineering production. However, for liquid sample detection, the rapid quenching of the plasma, the contamination of the optical system by the unstable liquid level, and the limited laser energy absorption of the plasma have limited the further development of LIBS technology. Here, a discharge-assisted LIBS technique (D-LIBS) for the detection of trace elements in solutions is proposed and compared with the conventional LIBS (C-LIBS).
Rapid sampling of mixed BaCl2 and NaCl2 solutions is performed using medium-speed filter paper. A Nd:YAG laser is implemented to generate plasmas containing the target elements on the filter paper. A discharge assistance consists mainly of a high voltage DC power supply, a capacitor, and a pair of rod electrodes. The capacitor is first charged by the high voltage DC power supply. The electrodes are respectively connected to the positive and negative terminals of the capacitor, and placed horizontally on the surface of the filter paper. Once the sample surface is ablated by the focused laser beam, the pre-existing plasma between the electrodes acts as the seed charged particles in the discharge gap, which rapidly ignites a strong discharge there.
Compared to the time-integrated spectra in C-LIBS and D-LIBS, the LIBS signal has been greatly increased by using the discharge assistance. Emission lines of BaⅡ455.40 nm and NaⅠ588.99 nm are respectively enhanced to 30-fold and 6-fold. The spectral intensities in C-LIBS and D-LIBS are positively correlated with laser energy. However, the spectral enhancement factors show higher values at small laser energy conditions, and the BaⅡ spectral enhancement factor decreases from 30 (20 mJ) to 2 (50 mJ) with increasing laser energy. Compared with the spectral signal-to-noise ratio (SNR) in C-LIBS, D-LIBS results in a SNR enhancement of more than 1 order of magnitude. When the laser energy is 20 mJ, the SNR enhancement factor of BaⅡ spectral line and Na I spectral line is 56 and 16, respectively. In addition, the quantitative analysis performance of C-LIBS and D-LIBS for trace metal elements in solution under different laser energy conditions are comparatively studied. The limit of detection (LoD) of Ba is decreased along with the laser energy in C-LIBS, reaching 0.823 mg/L at 50 mJ. Moreover, under the optimal condition the LoD is reduced from 12.5 mg/L in C-LIBS to 0.26 mg/L in D-LIBS, and the detection sensitivity of LIBS technique is increased by 47-fold due to the discharge assistance.
The following conclusions can be drawn from the experimental results: (1) The spectral intensity, SNR can be enhanced by over 1 order of magnitude. The increases in the intensity and SNR of the plasma spectra are due to the additional electrical energy injection resulting in the reheating and excitation of the plasma. (2) The spectral intensity and SNR are positively correlated with laser energy. The enhancement factor reaches the maximum in the smallest laser energy condition. This is due to the fact that the lower the laser energy, the smaller the mass of sample ablated, and therefore the more significant the enhancement effect is when the plasma is excited by the additional discharge. (3) The quantitative analysis of LIBS can be efficiently enhanced over 1 order of magnitude by the discharge assistance. And the LoD is reduced to 0.26 mg/L which is 1/48 of the original level.
|
|
Received: 13 January 2023
|
|
|
|
|
|
[1] Hilbk-Kortenbruck F, Noll R, Wintjens P, et al.Analysis of heavy metals in soils using laser-induced breakdown spectrometry combined with laser-induced fluorescence[J]. Spectrochimica Acta Part B: Atomic Spectroscopy, 2001, 56(6): 933-945.
[2] Sirven J -B, Bousquet B, Canioni L, et al.Qualitative and quantitative investigation of chromium-polluted soils by laser-induced breakdown spectroscopy combined with neural networks analysis[J]. Analytical and Bioanalytical Chemistry, 2006, 385(2): 256-262.
[3] Piñon V, Mateo M P, Nicolas G.Laser-induced breakdown spectroscopy for chemical mapping of materials[J]. Applied Spectroscopy Reviews, 2013, 48(5): 357-383.
[4] Dong Fengzhong, Chen Xinglong, Wang Qi, et al.Recent progress on the application of LIBS for metallurgical online analysis in China[J]. Frontiers of Physics, 2012, 7(6): 679-689.
[5] Jiang Chenyu, Cui Jinjiang, Shi Yanbo, et al.LIBS: a new method for heavy metal in biomedical field and applied in plasma medical[C]//International Symposium on Bioelectronics and Bioinformations, Suzhou, China, 2011: 210-213.
[6] Colao F, Fantoni R, Lazic V, et al.Investigation of LIBS feasibility for in situ planetary exploration: an analysis on Martian rock analogues[J]. Planetary and Space Science, 2004, 52(1/2/3): 117-123.
[7] Gottfried J L, De Lucia F C, Munson C A, et al. Laser-induced breakdown spectroscopy for detection of explosives residues: a review of recent advances, challenges, and future prospects[J]. Analytical and Bioanalytical Chemistry, 2009, 395(2): 283-300.
[8] Vinić M, Aruffo E, Andreoli F, et al.Quantification of heavy metals in oils with µL volume by laser induced breakdown spectroscopy and minimazing of the matrix effect[J]. Spectrochimica Acta Part B: Atomic Spectroscopy, 2020, 164: 105765.
[9] Reis B F, Knochen M, Pignalosa G, et al.A multicommuted flow system for the determination of copper, chromium, iron and lead in lubricating oils with detection by flame AAS[J]. Talanta, 2004, 64(5): 1220-1225.
[10] Souza R M, da Silveira C L P, Aucélio R Q. Determination of refractory elements in used lubricating oil by ICPOES employing emulsified sample introduction and calibration with inorganic standards[J]. Analytical Sciences, 2004, 20(2): 351-355.
[11] Rohman A, Che Man Y B. Fourier transform infrared (FTIR) spectroscopy for analysis of extra virgin olive oil adulterated with palm oil[J]. Food Research International, 2010, 43(3): 886-892.
[12] Mastoi G M, Khuhawar M Y, Bozdar R B.Spectrophotometric determination of vanadium in crude oil[J]. Journal of Quantitative Spectroscopy and Radiative Transfer, 2006, 102(2): 236-240.
[13] Escobar M P, Smith B W, Winefordner J D.Determination of metallo-organic species in lubricating oil by electrothermal vaporization inductively coupled plasma mass spectrometry[J]. Analytica Chimica Acta, 1996, 320(1): 11-17.
[14] 夏文杰, 刘定新. Ar等离子体射流处理乙醇水溶液的放电特性及灭菌效应[J]. 电工技术学报, 2021, 36(4): 765-776.
Xia Wenjie, Liu Dingxin.Discharge characteristics and bactericidal effect of Ar plasma jet treating ethanol aqueous solution[J]. Transactions of China Electrotechnical Society, 2021, 36(4): 765-776.
[15] 徐晗, 陈泽煜, 刘定新. 大气压冷等离子体处理水溶液:液相活性粒子检测方法综述[J]. 电工技术学报, 2020, 35(17): 3561-3582.
Xu Han, Chen Zeyu, Liu Dingxin.Aqueous solutions treated by cold atmospheric plasmas: a review of the detection methods of aqueous reactive species[J]. Transactions of China Electrotechnical Society, 2020, 35(17): 3561-3582.
[16] 石富坤, 郭雨怡, 王群, 等. 大气压低温等离子体射流制备刺激响应型凝胶[J]. 电工技术学报, 2021, 36(15): 3147-3153.
Shi Fukun, Guo Yuyi, Wang Qun, et al.Polymerization of stimuli-responsive hydrogels by using a cold atmospheric plasma jetrevoke[J]. Transactions of China Electrotechnical Society, 2021, 36(15): 3147-3153.
[17] 林茂, 徐浩军, 魏小龙, 等. 放电参数变化对电感耦合等离子闭式等离子体空间分布特性研究[J]. 电工技术学报, 2022, 37(5): 1294-1304.
Lin Mao, Xu Haojun, Wei Xiaolong, et al.Study on spatial distribution of inductive coupled plasma closed plasma with discharge parameter variation[J]. Transactions of China Electrotechnical Society, 2022, 37(5): 1294-1304.
[18] Wu C, Sun D X, Su M G, et al.Quantitative analysis of Pb in soil samples by laser-induced breakdown spectroscopy with a simplified standard addition method[J]. Journal of Analytical Atomic Spectrometry, 2019, 34(7): 1478-1484.
[19] Bellou E, Gyftokostas N, Stefas D, et al.Laser-induced breakdown spectroscopy assisted by machine learning for olive oils classification: the effect of the experimental parameters[J]. Spectrochimica Acta Part B: Atomic Spectroscopy, 2020, 163: 105746.
[20] Chen Youyuan, Yin Pengkun, Peng Zhengying, et al.High-throughput recognition of tumor cells using label-free elemental characteristics based on interpretable deep learning[J]. Analytical Chemistry, 2022, 94(7): 3158-3164.
[21] Skočovská K, Novotný J, Prochazka D, et al.Optimization of liquid jet system for laser-induced breakdown spectroscopy analysis[J]. The Review of Scientific Instruments, 2016, 87(4): 043116.
[22] Aras N, Yeşiller S Ü, Ateş D A, et al. Ultrasonic nebulization-sample introduction system for quantitative analysis of liquid samples by laser-induced breakdown spectroscopy[J]. Spectrochimica Acta Part B: Atomic Spectroscopy, 2012, 74/75: 87-94.
[23] Sobral H, Sanginés R, Trujillo-Vázquez A.Detection of trace elements in ice and water by laser-induced breakdown spectroscopy[J]. Spectrochimica Acta Part B: Atomic Spectroscopy, 2012, 78: 62-66.
[24] Fang Li, Zhao Nanjing, Ma Mingjun, et al.Detection of heavy metals in water samples by laser-induced breakdown spectroscopy combined with annular groove graphite flakes[J]. Plasma Science and Technology, 2019, 21(3): 034002.
[25] Lazic V, Jovicevic S, Fantoni R, et al.Efficient plasma and bubble generation underwater by an optimized laser excitation and its application for liquid analyses by laser-induced breakdown spectroscopy[J]. Spectrochimica Acta Part B: Atomic Spectroscopy, 2007, 62(12): 1433-1442.
[26] Lei Bingying, Xu Boping, Wang Jing, et al.Large modulation of ion dynamics for discharge-assisted laser-induced breakdown spectroscopy[J]. Cell Reports Physical Science, 2023, 4(2): 101267.
[27] Jung J, Yang J H, Yoh J J.An optimal configuration for spark-induced breakdown spectroscopy of bulk minerals aimed at planetary analysis[J]. Journal of Analytical Atomic Spectrometry, 2020, 35(6): 1103-1114.
[28] 刘晓鹏, 董曼玲, 邓虎威, 等. 空气间隙击穿后放电通道内的气体运动特性[J]. 电工技术学报, 2021, 36(13): 2667-2674.
Liu Xiaopeng, Dong Manling, Deng Huwei, et al.Movement characteristics of the gas in discharge channel after air gap breakdown[J]. Transactions of China Electrotechnical Society, 2021, 36(13): 2667-2674.
[29] 徐学基, 诸定昌. 气体放电物理[M]. 上海: 复旦大学出版社, 1996.
[30] Eschlböck-Fuchs S, Kolmhofer P J, Bodea M A, et al.Boosting persistence time of laser-induced plasma by electric arc discharge for optical emission spectroscopy[J]. Spectrochimica Acta Part B: Atomic Spectroscopy, 2015, 109: 31-38.
[31] Xu Boping, Liu Simeng, Lei Bingying, et al.A hybrid method combining discharge-assisted laser induced breakdown spectroscopy with wavelet transform for trace elemental analysis in liquid targets[J]. Journal of Analytical Atomic Spectrometry, 2022, 37(6): 1350-1359.
[32] Goueguel C L, Bhatt C R, Jain J C, et al.Quantification of dissolved metals in high-pressure CO2-water solutions by underwater laser-induced breakdown spectroscopy[J]. Optics & Laser Technology, 2018, 108: 53-58.
[33] 李文平, 周卫东. 溶液中Ba元素的水下单脉冲与正交双脉冲LIBS的比较研究[J]. 中国激光, 2019, 46(9): 306-315.
Li Wenping, Zhou Weidong.Comparative study of underwater single pulse and orthogonal double pulse laser-induced breakdown spectroscopy of Barium element in solution[J]. Chinese Journal of Lasers, 2019, 46(9): 306-315. |
|
|
|
2023, Vol. 38 
