Sampling considerations when analyzing micrometric-sized particles in a liquid jet using laser induced breakdown spectroscopy

Abstract

International audiencePollution of water is a matter of concern all over the earth. Particles are known to play an important role in the transportation of pollutants in this medium. In addition, the emergence of new materials such as NOAA (Nano-Objects, their Aggregates and their Agglomerates) emphasizes the need to develop adapted instruments for their detection. Surveillance of pollutants in particulate form in waste waters in industries involved in nanopartide manufacturing and processing is a telling example of possible applications of such instrumental development. The LIBS (laser-induced breakdown spectroscopy) technique coupled with the liquid jet as sampling mode for suspensions was deemed as a potential candidate for on-line and real time monitoring. With the final aim in view to obtain the best detection limits, the interaction of nanosecond laser pulses with the liquid jet was examined. The evolution of the volume sampled by laser pulses was estimated as a function of the laser energy applying conditional analysis when analyzing a suspension of micrometric-sized particles of borosilicate glass. An estimation of the sampled depth was made. Along with the estimation of the sampled volume, the evolution of the SNR (signal to noise ratio) as a function of the laser energy was investigated as well. Eventually, the laser energy and the corresponding fluence optimizing both the sampling volume and the SNR were determined. The obtained results highlight intrinsic limitations of the liquid jet sampling mode when using 532 nm nanosecond laser pulses with suspensions

Recent development and application of laser induced breakdown spectroscopy

“…Bukhari等人 [30] 用吸收纸提取水样品中杂质, 采用Nd:YAG激光器(1064 nm, 10 ns, 10 Hz, 146.7 mJ-铬, 89.5 mJ-镉)检测制革废水中重金属铬和镉, 在延时4.5 μs、样品表面距离镜头70 mm、采光系统 距离样品表面7 mm的优化条件下, 得到了信噪比最 好的光谱. Faye等人 [31] 应用LIBS对含有硼硅玻璃颗 粒的受污染水进行监测, 也取得了理想效果. 目前用LIBS检测土壤成分被认为是最直接最有 效的方法.…”

Detection of trace metals in water by filament- and plasma-grating-induced breakdown spectroscopy

“…Grated plasma channels are expected to be immune to aqueous surface wobbling and wavelength-scale microstructures of plasma modulation could be even maintained across the wobbling air–solution interfaces. For verification of its technological effectiveness as well as further developments of its potential applications in detecting aqueous solutions, there remain some intriguing questions deserving further experimental explorations, such as how to overcome side effects from bubble generation induced by plasma gratings, 51 – 53 how to increase the plasma excitations dramatically in aqueous solutions, and how to effectively evade random multiple filamentation breakup during filaments passing through air–aqueous interfaces.…”

Determination of Arsenic by Hydride Generation—Laser-Induced Breakdown Spectroscopy: Characterization of Interelement Interferences

“…While LIBS offers fast and real-time measurement easily for the analysis of solids, liquid sample analysis by LIBS still needs some special methodologies to be performed due to inherent drawbacks of the technique encountered. Plasma formation; on flowing jet liquids (Haisch et al 1997;Kumar, Yueh, and Singh 2003;Feng et al 2010;Faye et al 2014), inside bubbles (Koch et al 2006), on liquid droplets (Janzen et al 2005;Cahoon and Almirall 2012), aerosol formation by nebulization (Radziemski et al 1983;Aras et al 2012) or by electro-spray ionization (Huang et al 2002;Huang, Liu, and Lin 2007), changing the samples physical condition by freezing (Cáceres et al 2001), absorbing the liquid on a solid substrate (Chen et al 2008;Sarkar et al 2010) and use of sequential laser pulses (Cremers, Radziemski, and Loree 1984;Pearman, Scaffidi, and Angel 2003;Rai, Yueh, and Singh 2008;Lee et al 2011;Rifai et al 2012) are some of the efforts devoted to increase analytical capability of the LIBS technique in liquid analysis.…”