Direct Measurement of Organic Micropollutants in Water and Wastewater Using Fluorescence Spectroscopy

Quantifying organic micropollutants (OMPs) in aquatic environments and assessing their removal by water treatment requires expensive and time-consuming analyses typically using liquid chromatographic separation and tandem mass spectrometry (LC-MS/MS). In this study, we evaluated the potential for detecting fluorescent OMPs via spectroscopy, which is cheap, rapid, and widely accessible. The method involved using a priori PARAFAC models to eliminate interfering background fluorescence emitted by naturally occurring dissolved organic matter. Of 20 screened pharmaceutical OMPs, three (ciprofloxacin, naproxen, and zolpidem) with calculated fluorescence quantum yields 0.14, 0.21, and 0.71, respectively, could be quantified in the low μg L^-1 range when added alone or in combination to water samples without any sample pretreatment other than filtration and pH adjustment. Limits of detection for all three OMPs were 1.0-3.3 μg L^-1 in surface waters, while in wastewater, they were 0.6-9.0 μg L^-1 for ciprofloxacin and naproxen and 1.0-2.6 μg L^-1 for zolpidem. Given the high cost of pharmaceutical analyses and widespread availability of fluorometers, the new approach will improve access to rapid and cost-effective results by supporting data-intensive lab-scale studies, wherein the types of OMPs studied and their concentration ranges are under the control of the analyst.