New Online Detection Device Improves Water Quality Monitoring

In a recent study from researchers at East China University of Science and Technology, Henan Academy of Sciences, and North China University of Water Resources and Electric Power, a novel continuous solid-phase extraction spectroscopy (CSPES) was tested to see how effective it was at monitoring water quality. The findings of this study were published in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (1).

Assessing water quality is important to ensure the continued health of humans and animals. Because water is also a finite resource, it is imperative that as little as possible goes to waste. Monitoring water quality is done for several major purposes. For one, it helps scientists identify changes in water quality over time, as well as specific existing water quality issues that require immediate attention (2). Monitoring water quality also helps determine the success or failure of any environmental sustainability goal, making sure that the water complies with any pollution regulations (2).

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In this study, the researchers proposed using the CSPES system to monitor water quality. The authors explained in their study that CSPES is designed to resolve the limitations and drawbacks of other traditional methods (1). For example, fluorescence spectroscopy is often used to monitor water quality. However, it is labor-intensive and susceptible to environmental interferences (1). On the other hand, CSPES is compact and portable, allowing for the in-situ and real-time collection of spectral signals during the solid-phase extraction (SPE) process (1). By isolating the analysis chamber in a sealed dark environment, CSPES eliminates stray light interference, ensuring accurate measurements even in challenging conditions (1).

The CSPES device works through the following process: the water samples pass through a membrane material for SPE; as the analytes enrich on the membrane, their dynamic spectral changes are captured in real time, enabling continuous monitoring of environmental pollutants (1). Then, because CSPES is equipped with automated software, the device can handle the sampling and detection without the need for any labor-intensive process (1).

At the heart of the CSPES device is a robust quantitative analysis model based on adsorption kinetics theory (1). The model establishes a relationship between spectral data and component concentrations, allowing for the precise quantification of waterborne pollutants, even in multi-component mixtures with overlapping spectra (1). Using the least squares method, the research team developed a concentration calculation framework that offers improved predictive accuracy (1).

The researchers validated CSPES by using both single-component and binary-component sample systems, including pollutants such as fluoranthene (FL), benzo[k]fluoranthene (B[k]F), and rhodamine 6G (R6G) (1). The CSPES device achieved relative errors (RE) ranging from 0.45% to 8.75% and relative standard deviations (RSD) of less than 3% (1). Additionally, real-world applications yielded spiked recovery rates of 86.8% to 124.4%, with relative standard deviation (RSD) values between 0.33% and 2.22% (1).

The researchers explained in their paper that CSPES has one unique advantage in that it can handle complex sample systems. In the study, the researchers demonstrated the device’s capability to analyze multiple components simultaneously when they used chemometric multivariate calibration methods (1). This capability stems from the distinct enrichment kinetic curves and spectral characteristics of different pollutants, which the model integrates into a highly selective and sensitive analysis framework (1).

Compact and portable instrumentation is growing in demand and popularity. The CSPES device is the latest addition to this new wave of instruments. Its compact design and cost-effective operation make it suitable for widespread deployment, including in remote or resource-limited settings (1).

Looking ahead, the researchers envision further advancements in CSPES technology. These include developing methods for the simultaneous analysis of multiple components in more complex samples, enhancing its accuracy and versatility. By extending its application to broader fields such as agricultural runoff monitoring and industrial wastewater analysis, the CSPES device has the potential to become an indispensable tool for environmental scientists and policymakers.

References

1. Shen, J.; Li, L.; Xu, K.; et al. Continuous Solid-phase Extraction Spectroscopy and its Quantification Method for Trace Analysis. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2025, 327, 125396. DOI: 10.1016/j.saa.2024.125396
2. U.S. Environmental Protection Agency, An Introduction to Water Quality Monitoring. EPA.gov. Available at: https://archive.epa.gov/water/archive/web/html/monintr.html#:~:text=There%20are%20many%20ways%20to,metals%2C%20oils%2C%20and%20pesticides. (accessed 2025-01-22).