New Surface-Enhanced Raman Spectroscopy Substrates via Self-Assembly of Silver Nanoparticles for Perchlorate Detection in Water

Abstract

Perchlorate (ClO₄⁻) has recently emerged as a widespread contaminant in drinking water and groundwater supplies in the United States, and a need exists for rapid detection and monitoring of this contaminant. In this study, surface-enhanced Raman spectroscopy (SERS) was studied as a means of ClO₄⁻ detection, and new sol-gel-based SERS substrates were developed by self-assembly of silver colloidal nanoparticles with various functionalized silane reagents. These substrate materials were tailored to allow detection of ClO₄⁻ in water with improved sorptivity, stability, and sensitivity and with the ability to detect ClO₄⁻ at concentrations as low as 10⁻⁶ M (or 100 μg/L) with good reproducibility. Similar techniques were used to fabricate capillary SERS flow cells by assembling functionalized silver nanoparticles capable of attracting ClO₄⁻ to the SERS surface or the internal wall of glass capillaries. These capillary flow cells could be readily configured to allow for in situ, nondestructive detection of ClO₄⁻ via fiber optics.