Ultra-sensitive detection of heavy metal ions in tap water by laser-induced breakdown spectroscopy with the assistance of electrical-deposition

Abstract

The trace heavy metal ions in tap water were electrically deposited on the surface of a high purity aluminium rod and then analyzed with laser-induced breakdown spectroscopy (LIBS). Cr³⁺, Mn²⁺, Cu²⁺, Zn²⁺, Cd²⁺ and Pb²⁺ in tap water samples were quantitatively analyzed and the calibration curves have been built up within the concentration range of 1–1000 μgL⁻¹. The limits of detection of these ions were determined to be 0.16–1.35 μgL⁻¹, which are improved 5–6 orders than directly analyzing aqueous solutions by LIBS. The influence of Ca²⁺ and Mg²⁺ in water at different concentrations to the quantitative analysis of trace heavy metal ions was evaluated. It is possible to realize reliable quantitative analysis by using different calibration curves according to the hardness of the analyzed water samples. LIBS plus electrochemical enrichment is a potential approach to high sensitivity detection of trace heavy metal ions in tap water and natural water samples, and it will find applications in environmental pollution monitoring.