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 microg/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.