Analysis of Heavy Metal Pollution in Soil Using Transversely Excited Atmospheric CO₂ Laser-Induced Plasma by Trapping the Soil in Microstructured Holes on Metal Subtargets

Abstract

A unique technique for direct analysis of soil samples utilizing a special advantage of a transversely excited atmospheric (TEA) CO(2) laser-induced plasma generated at atmospheric pressure on a metal target has been developed. In this technique, a metal subtarget, such as nickel plate, structured with intentional microholes on its surface, each with dimensions of around 100 microm in diameter and depth, was used to selectively trap small sized soil particles by immersing the metal plate subtarget into the polluted soil sample. The trapped small soil particles on the metal subtarget were irradiated by a TEA CO(2) laser (10.6 microm, 1.5 J, 200 ns) at atmospheric pressure under defocused condition with a spot size of 3 mm x 3 mm. This trapping and confining scheme substantially suppresses the blowing off effect; thus, the trapped soil particles can effectively be dissociated and atomized in the microstructured holes. Using this method of a microstructured metal plate subtarget, quantitative analysis was carried out on loam soil samples polluted by Pb. A linear calibration curve was obtained with a detection limit of approximately 50 mg/kg. Preliminary quantitative studies were carried out for a quartz sand sample containing Cr and Hg, resulting in linear calibration curves with detection limits of approximately 25 mg/kg and 10 mg/kg, respectively, at this stage. This technique is promising as a potential field screening tool for soil analysis.

Comparative study of Nd:YAG laser-induced breakdown spectroscopy and transversely excited atmospheric CO2 laser-induced gas plasma spectroscopy on chromated copper arsenate preservative-treated wood

“…In addition, we have confirmed by JAS method that the non-treated wood (blank wood) does not contain chromium. In order to compensate for the uncontrolled fluctuation of the laser plasma intensity produced on the sample, internal standardization was carried out using the background emission employed in our previous work [15]. The standard deviation was Fig.…”

Determination of low alloying element concentrations in cast iron by laser induced breakdown spectroscopy based on TEA CO2 laser system

“…Nevertheless, for the analysis of a certain type of samples higher precision and sensitivity were obtained with CO 2 compared to Nd:YAG laser. [13][14][15][16] In the present study, a laboratory LIBS setup was used, in which the infrared pulsed transversely excited atmospheric (TEA) CO 2 laser is applied as the excitation source and time-integrated space-resolved detection scheme is used for the acquisition of emission spectra. The main benefit of this non-gated LIBS system, compared to commonly practiced LIBS, is simplification of the instrumentation and its cost.…”

Laser Spectroscopy for Atmospheric and Environmental Sensing

“…LOD were between 0.029 and 0.59 mg/L, which is 2–3 orders of magnitude more sensitive than LIBS without a substrate. Other recent publications utilize a substrate to provide a restricted space for the sample, such as a metal plate with 100 μm holes for the analysis of soils by LIBS [132]. The authors claim that this system reduces lost sample particles during irradiation and that atomization and excitation are enhanced due to sample confinement in the surrounding metal.…”