Electrochemical enrichment-assisted LIBS using a microstructured silver needle electrode for ultrasensitive heavy metal analysis in water

In this study, a microstructured silver needle electrode was developed for electrochemical enrichment-assisted laser-induced breakdown spectroscopy (LIBS) for the ultrasensitive determination of heavy metals in water. The engineered surface microstructure allows the silver needle to serve not only as an efficient platform for ion enrichment but also as a signal-enhancing substrate for laser ablation. Compared with an untreated silver needle, the microstructured silver needle exhibits a rougher surface morphology and more available enrichment sites. These features promote the migration, adsorption, and accumulation, thereby significantly enhancing the LIBS signal intensity. SEM-EDS mapping further confirmed Cd accumulation on the electrode surface, with higher Cd content observed on the microstructured silver needle than on the smooth silver needle. Under the optimised conditions of 25 V and 25 min, Cd showed a linear response over the range of 1–20 µg L⁻¹ with a correlation coefficient (R²) of 0.998 and a limit of detection (LOD) of 0.513 µg L⁻¹. Pb exhibited linearity over 30–140 µg L⁻¹ with an R² of 0.993 and an LOD of 1.994 µg L⁻¹. Compared with the conventional electrochemical enrichment method, the proposed strategy improved the detection sensitivity by approximately tenfold. These results demonstrate that the present method provides an effective approach for the ultrasensitive analysis of heavy metals in water. This journal is © The Royal Society of Chemistry, 2026.