Fluorescence Spectroscopy Emerges as Rapid Screening Tool for Groundwater Contamination in Denmark

Recently, a group of researchers, led by Urban J. Wunsch at the Technical University of Denmark, investigated how fluorescence spectroscopy can be used as a rapid, on-site screening tool for detecting pharmaceutical contaminants in groundwater. This study, published in Chemosphere, addresses the negative environmental impact pharmaceutical residues have on the environment and public health by showing that fluorescence-based techniques can help visualize and delineate contaminant plumes more quickly and affordably than traditional laboratory methods (1).

Why Is Monitoring Groundwater Pollution Important?

Because of normal industry practices, industrial waste and residue occasionally end up in the groundwater, which poses risks to the local ecosystem, as well as health risks for humans. It is estimated that over 50% of the United States population relies on groundwater for drinking purposes (2). As a result, drinking contaminated groundwater can result in a majority of the population contracting serious diseases such as dysentery and hepatitis (2). Pharmaceutical residues are just one type of hazardous waste that enters groundwater. Septic systems, road salts, and refuse also end up in these water sources (2).

Unfortunately, current remediation efforts are not ideal. The methods primarily used often rely on labor-intensive and costly laboratory analyses to assess the distribution and movement of contaminant plumes (1). In this study, Wunsch’s team sought to assess whether optical methods, particularly fluorescence spectroscopy, could offer a faster and more practical approach for real-world applications (1).

What Did The Researchers Test In Their Study?

For the purposes of their study, the researchers focused their analysis on three pharmaceutical contaminants: sulfanilamide, sulfaguanidine, and sulfanilic acid. Each of these compounds, which originate from historical pharmaceutical waste, was found to emit strong fluorescence signals distinguishable from naturally occurring organic matter (1).

One important aspect to this study is that the researchers tested and compared the performance between benchtop spectrofluorometers and handheld ones. They found that the benchtop instrument achieved a limit of detection (LOD) of 14 μg/L for the sum of the three contaminants, whereas the handheld sensor yielded a less precise and higher LOD of 142 μg/L (1).

What Were The Challenges Encountered In This Study?

The researchers acknowledged that they encountered several challenges in applying fluorescence-based techniques, especially when dealing with complex mixtures of organic material. In particular, the co-occurrence of natural dissolved organic matter (DOM) often masked the fluorescent signal of the contaminants, making it difficult to quantify trace-level pollution (1). This issue was especially pronounced in areas with lower levels of contamination, where natural DOM fluorescence could overpower that of the pollutants (1).

The other challenge was that the three pharmaceutical contaminants tested were spectrally similar. As a result, common data analysis approaches, such as parallel factor analysis (PARAFAC), which is a machine learning-based method often used to improve selectivity and sensitivity in fluorescence measurements, couldn’t be used (1).

What Should Researchers Take Away From This Study?

Researchers should take away from this study that there are promising strategies to enhance fluorescence detection. For instance, low-volume solid-phase extraction (SPE) was used to selectively concentrate the contaminants before measurement, effectively lowering the detection limits (1). Additionally, the team proposed the use of an inexpensive, single-channel absorbance sensor to correct for inner filter effects.

The study also demonstrates that fluorescence-based methods can be used broadly in freshwater systems with low natural DOM concentrations (1). In these environments, where background fluorescence is minimal, optical screening could be especially effective as a preliminary tool for identifying contamination hotspots (1).

What Did The Authors Suggest Regarding Next Steps?

To conclude their article, Wunsch’s team emphasized the importance of building a centralized database cataloging the absorbance and fluorescence properties of known contaminants. This would solve a current limitation in this space and facilitate the identification of previously undocumented fluorescent compounds in aquatic systems (1).

This study demonstrates the viability of using fluorescence spectroscopy as a rapid, cost-effective screening method for contaminant detection in water resources. Although limitations remain, the technique shows promise as a complementary tool to traditional chemical analyses, especially in resource-constrained or remote settings (1).

References

1. Vinther, L.; Broholm, M.; Schittich, A.-R.; et al. Fluorescence Spectroscopy as an Indicator Tool for Pharmaceutical Contamination in Groundwater and Surface Water. Chemosphere 2025, 372, 144009. DOI: 10.1016/j.chemosphere.2024.144009
2. Groundwater Foundation, Groundwater Contamination. Groundwater.org. Available at: https://groundwater.org/threats/contamination/ (accessed 2025-05-19).