High-sensitivity analysis of trace elements in water using femtosecond LIBS with dry droplet pretreatment on a metallic substrate

Abstract

Detection of heavy metals in environmental water is important in addressing water pollution. In this study, a simple and effective strategy was proposed that utilized femtosecond laser-induced breakdown spectroscopy (fs-LIBS) to investigate the effect of titration number in dry droplet pretreatment on an Al substrate for detecting trace elements in aqueous solutions. This method aimed to enhance signals for highly sensitive detection of trace metal elements in liquid samples. Cr, Pb, and Cu were detected in water solutions with 1, 2, and 4 titration numbers. The limit of detection (LOD) was calculated for Cr, Pb, and Cu at 1, 2, and 4 titrations, respectively. The LODs for Cr, Pb, and Cu obtained by 4 titration numbers were 0.19, 1.40, and 0.24 ng mL⁻¹, respectively. The calculated R² for Cr, Cu was > 0.99 and for Pb > 0.98, which were satisfactory results and demonstrated the feasibility of using increased titration times in dry droplet pretreatment for analyzing liquid samples. Applying increased titration numbers in high-performance signal enhancement undoubtedly elevates the sensitivity of fs-LIBS analysis methods to a new level.