Sensitive detection of trace heavy metals in water by laser-induced breakdown spectroscopy with EDTA-modified filter paper enrichment

Abstract

To address the challenges in detecting trace heavy metals in water, this study developed a laser-induced breakdown spectroscopy (LIBS) method integrated with EDTA-modified filter paper for the rapid and sensitive detection of copper, lead, and chromium in aqueous solutions. The filter paper was chemically modified to immobilize EDTA molecules, enabling efficient adsorption and pre-concentration of the target ions. Key parameters, including pH, adsorption time, and temperature, were optimized to maximize the signal intensity, resulting in a 6.5- to 7.8-fold enhancement compared with an unmodified substrate. The method demonstrated low detection limits (0.023–0.135 mg L⁻¹), excellent reproducibility (relative standard deviation <7.5%), and strong anti-interference capability against common coexisting ions. When applied to real water samples (tap water, river water, and industrial wastewater), the method achieved recoveries of 96.5–109%, which were consistent with the ICP-MS results. The EDTA-filter paper-LIBS approach provides a simple, reliable, and portable solution for on-site monitoring of trace heavy metals, demonstrating great potential for environmental and water safety applications.