Surfactant-assisted au nanostructures with Micro-hole Array sprayer for enhanced LIBS detection of trace heavy metals in water

Abstract

Heavy metal pollution threatens human health and ecosystems, and countries have established strict standards for heavy metal content in water bodies. This paper presents a new method based on micro-hole array sprayed on solid substrate enhanced laser-induced breakdown spectroscopy (MASSS-LIBS) technology and NELIBS, which enables high sensitivity and multi-element detection at the μg/L level. The method involves sequentially spraying metal nanomaterials, water samples, and surfactants onto a silicon substrate to form nanostructures that are conducive to LIBS analysis. Experimental research examined the impact of key parameters, including surfactant type and nanoparticle preparation, on signal quality. Results showed significant improvements in signal intensity and stability after forming nanostructures compared to using only Au nanoparticles. Different surfactants provided varying LIBS enhancements for heavy metals, with sodium dodecyl sulfate (SDS) demonstrating superior enhancement and stability for Pb, Cr, Cu, and Mn. Controlling nanoparticle density through spraying time for Au NPs helped manage nanostructure surface density and reduce Au nanoparticle loss, further enhancing LIBS signals. Under optimized parameters, the intensity of LIBS spectral peaks following nanostructure formation was approximately 10 times higher than that observed without nanostructures, with a stability of 6 %. The LoD for Mn reached sub-μg/L levels, while the LoD for Cu, Cr, and Pb was approximately several μg/L, demonstrating a one-order-of-magnitude improvement. In eleven quantitative inversion experiments in the low concentration range of tens of μg/L. Overall, this method shows potential as an alternative for qualitative and quantitative analyses in water quality testing.