Raman spectroscopic detection for perchlorate at low concentrations

Perchlorate (ClO₄^-) has recently emerged as a widespread environmental contaminant found in groundwater and surface water, and there is a great need for rapid detection and monitoring of this contaminant. In this study, we explore the use of surface-enhanced (SERS) and normal Raman spectroscopy for detecting ClO₄^- at low concentrations. We found that ClO₄^- is SERS active and, for the first time, were able to detect ClO₄^- at concentrations as low as 10^-6-10^-7 M (or 10-100 μg/L) through the application of silver SERS substrates or selective sorbents such as bifunctional anion-exchange resins. The use of selective sorbents greatly enhanced the reproducibility and sensitivity of ClO₄^- detection by normal Raman spectroscopy. Further exploration and research may allow application of these techniques for in situ, real-time detection and monitoring of ClO₄^- in environmental samples at even lower concentrations.