Hot spot-normalized surface-enhanced raman spectroscopy platform for real-time detection of chlorine photolysis reactive species and chloride ions
A novel SERS-based sensing platform using plasmonic gold nanoparticles to monitor reactive oxidant species and chloride ion production during chlorine and chloramine photolysis. Enables real-time detection of mono-, di-, and tri-chloramine and quantification of organic layer transformation on nanoparticle surfaces, with applications in water treatment monitoring and disinfection byproduct analysis.
Overview
This solution offers a sensing and analytical platform based on hot spot-normalized surface-enhanced Raman spectroscopy (HSNSERS) for monitoring the chemistry of chlorine and chloramine photolysis in water systems. The technology detects reactive oxidant species—including hydroxyl radicals, reactive chlorine species, and ozone—and quantifies the chloride ions and organic transformation products generated during UV-driven disinfection processes. By leveraging the enhanced electromagnetic fields at plasmonic nanoparticle hot spots, the platform provides real-time, label-free detection of mono-, di-, and tri-chloramine species through their unique Raman fingerprints. This capability addresses a critical need in water treatment for understanding and controlling disinfection chemistry, with potential extensions to environmental monitoring and public health protection.
Technical specifications
Key features:
- HSNSERS detection platform built on gold nanoparticle substrates that amplify Raman signals at nanoscale hot spots, enabling trace-level detection of reactive species
- Direct chloramine speciation through fingerprint Raman spectra, allowing discrimination between mono-, di-, and tri-chloramine forms
- Real-time monitoring of organic layer dynamics (citrate, chloroanilines, and related compounds) on nanoparticle surfaces during photolysis reactions
- pH- and wavelength-dependent sensitivity, with optimized detection under acidic conditions (pH <7.5) and UV-C irradiation (254 nm)
- Multivariate analysis integration combined with liquid chromatography-mass spectroscopy validation for robust product identification and quantification
- Scalable SERS grid design (3 cm × 2 cm × 0.3 cm) incorporating 1,500 detection zones and 1,500 reference zones for high-throughput screening
Technology readiness level
The HSNSERS sensitivity and reproducibility have been validated in laboratory studies, and the kinetics of chloride adsorption and organic layer transformation on gold nanoparticle surfaces have been quantified. Preliminary work has confirmed that chlorine and chloramine photolysis rapidly converts these species to chloride under UV-C irradiation within seconds. The next phase involves fabricating a SERS grid coated with an organic layer, exposing it to tap water under controlled UV conditions, and validating reaction products using HSNSERS combined with multivariate analysis and mass spectroscopy. The projected timeline for this validation phase is approximately one year, after which the platform will be positioned for pilot-scale evaluation in water treatment applications.
About University of Wisconsin, Madison
The University of Wisconsin–Madison is the state’s flagship public research university, a comprehensive institution with a large research enterprise and broad disciplinary breadth. Industry engages through shared instrumentation, pilot‑scale testbeds, and co-located core facilities that support prototyping and scale-up. An affiliated research and technology park hosts startups and corporate R&D, while integration with a major hospital system enables clinical translation; a statewide extension network connects campus advances to companies and communities across Wisconsin. Research is sustained by competitive federal funding from agencies such as NIH, NSF, DOE, USDA, and DoD, alongside state and industry partnerships. Dedicated commercialization support—through an affiliated foundation and campus offices—provides IP management, licensing, startup mentoring, and flexible, industry-friendly agreements.
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