Laser-Induced Breakdown Spectroscopic (LIBS) Analysis of Trace Heavy Metals Enriched by Al2O3 Nanoparticles

Abstract

We demonstrated a unique method for the detection of heavy metals, such as Ni, Cr, and Cd, at trace level in aqueous solutions by laser induced breakdown spectroscopy (LIBS) enriched by aluminum oxide (Al2O3) nanoparticles (NP) adsorption. Al2O3 NPs were used for the sample phase transformation and heavy metals pre-concentration because of its excellent adsorption capacity and sparse spectral lines. The influence of laser wavelength and laser irradiance on the signal intensity was investigated. With 45 mL solutions used for enrichment and adsorption, limits of detection obtained for Ni, Cr, and Cd were 9.61, 8.49, and 71.6 μg/L under 532 nm laser ablation, and 22.5, 20.4, and 83.8 μg/L under 1064 nm laser ablation, respectively. The relative standard deviations of all elements were about 12% or 13%. Moreover, Al2O3 NPs adsorption enrichment of target elements was verified and the detection sensitivity was improved by increasing the amount of sample solutions.