Laser-Induced Breakdown Spectroscopy of Liquids: Aqueous Solutions of Nickel and Chlorinated Hydrocarbons

Abstract

Spectrochemical analyses of aqueous solutions containing nickel or the chlorinated hydrocarbons (CHCs) C₂Cl₄, CCl₄, CHCl₃, and C₂HCl₃ were performed with the use of laser-induced breakdown spectroscopy. A Nd:YAG laser operating at 60 mJ/pulse was focused onto the surface of the liquid. Elemental line intensities were monitored in the laser-produced plume as a function of analyte concentration to determine detection limits. The limits of detection for nickel in water were 36.4 ± 5.4 mgAL and 18.0 ± 3.8 mg/L for laser irradiation at 1.06 μm and 355 nm, respectively. Ablation of pure CHCs at 355 nm produced extremely intense plasma emissions that primarily consisted of spectroscopic features attributed to CN, C₃, H, N, and Cl. The spectra were structurally identical for all the CHCs except for differences in the intensities of various emission lines. With the use of emission from neutral atomic chlorine as an identifier for CHC contamination of water, no detectable traces of these elements were observed in saturated aqueous solutions. The detection limits for the CHCs were well above the saturation limits of CHC in water.