Surface-enhanced Raman spectroscopic analysis of emerging contaminants in drinking water

Description:
Emerging contaminants (ECs) pose threats to public health due to their environmental prevalence and potential toxicity. The occurrence of ECs in drinking water supplies has been frequently reported. Unfortunately, the standard methods for EC analysis are usually based on the expensive and time-consuming liquid chromatography-tandem mass spectrometry, which is unlikely to fulfill the growing demand for EC monitoring. Surface-enhanced Raman spectroscopy (SERS) is a promising complementary tool for the standard methods because of its fast speed, fingerprinting selectivity, and potential for field deployment. This presentation summarizes our recent studies on SERS detection of emerging contaminants in drinking water. The first half of this presentation will be focused on the SERS detection of imidacloprid in the tap water of Madison, Wisconsin. Imidacloprid is a neonicotinoid insecticide that targets the central nervous system of insects by imitating nicotine. To achieve rapid and inexpensive detection of imidacloprid, a “mixing-and-detecting” method is proposed using the benchmark citrate-coated gold nanoparticle (AuNP) colloid as the SERS substrate. We systematically investigated the reproducibility of the imidacloprid SERS fingerprint as a function of its concentration. We also examined the influence of water matrices on the sensitivity and reproducibility of SERS for imidacloprid analysis. The second half of this presentation will be used to introduce our ongoing efforts on label-free SERS detection of per- and polyfluoroalkyl substances (PFAS) in drinking water. PFAS are publicly known as "forever chemicals" because their strong carbon-fluorine backbones make them resistant to environmental degradation. As a prerequisite for label-free PFAS detection, we have established a Raman library of typical PFAS commonly detected in drinking water supplies and elucidated the relationship between PFAS Raman spectra and their chemical structures.

Speaker: Haoran Wei - University of Wisconsin-Madison
Dr. Haoran Wei is currently an assistant professor in the Department of Civil and Environmental Engineering at the University of Wisconsin–Madison. He leads the Environmental Analytical Technology Laboratory which is located in the historical Water Science and Engineering Laboratory building. His current research is focused on developing innovative analytical technologies for the rapid and inexpensive detection of emerging contaminants in drinking water. Before starting his independent academic career, Dr. Wei worked as a postdoctoral associate in the Department of Chemical and Environmental Engineering at Yale University and obtained his Ph.D. degree in Civil and Environmental Engineering from Virginia Tech.