IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 BOOK OF ABSTRACTS 90 Environment, Agriculture, and Forestry Tuesday, 25 August 2026 / Hall B+C nm and a minor band at 275 nm/345 nm. DEP, compared to DBP, showed similar, but still visually unique A-TEEM contours. The DBP and DEP contours were both easily distinguishable visually from the typical natural DOC contours in the drinking water matrix associated with fulvic- and humic acid-like components and protein-like components. The data was evaluated using Parallel Factor Analysis (PARAFAC) to identify the components associated with the phthalates and background DOC. The PARAFAC scores associated with DBP and DEP were evaluated and compared to show DBP exhibited a significantly higher fluorescence yield (1.45x) than DEP on a concentration basis. For the weaker DEP, the linear regressions were evaluated for (A) the full working range (0-765 mg/L) and also (B) from 0-65 mg/L to more accurately determine the Limit of Detection (LOD) and Quantification (LOQ). For DEP, LOD/LOQ is determined as 3.3 and 10 times the Root Mean Square Error of the regression to be 1.05 and 3.17 mg/L, respectively. Thus, we conclude that direct reagent free analysis of these phthalate esters can be determined with detection and quantification limits below the range of their reported toxic effects in drinking water matrices. Further, improvements with respect to optimized instrument and experimental conditions could potentially improve these detection limits considerably. References 1. L. Wang, T. Yuan, Y.Chu Kwa and M. Jong, Environmental Science & Health 44 (2025) 10. 2. United States Environmental protection Agency, Risk Evaluation for Dibutyl Phthalate (DBP), December 2025 3. H. Song, H.J Lim and A. Son, Royal Society of Chemistry 14 (2024) 20585-20594. Acknowledgement We would like to thank the University of South Africa for funding this project, as well as our collaborators at HORIBA Instruments Incorporated, Piscataway, NJ, USA, for their support and training on the A-TEEM technique.
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