SPE – HPLC – UV determination of NSAIDs in freshwater: Analytical optimization and environmental risk assessment in northwestern Tunisia

Abstract Non‐steroidal anti‐inflammatory drugs (NSAIDs) are among the most frequently detected emerging contaminants in aquatic environments. Their occurrence and environmental fate are governed by complex interactions involving physicochemical and environmental factors. This study aimed to develop, validate, and apply a reliable HPLC–UV method for the simultaneous determination of three NSAIDs: ibuprofen, ketoprofen, and fenoprofen in freshwater samples collected from five sites in northwestern Tunisia. Several experimental parameters were systematically optimized before selecting the final analytical conditions for the analysis of environmental samples. The analytical procedure consisted of off‐line solid‐phase extraction (SPE) followed by HPLC–UV analysis. The method showed excellent linearity ( R 2 ≥0.997), with limits of detection (LODs) ranging from 0.08 to 0.12 μg L −1 and limits of quantification (LOQs) from 0.25 to 0.37 μg L −1 . Recoveries at two spiking levels (1 and 10 μg L −1 ) ranged from 81% to 97%, with relative standard deviations (RSDs) below 3.8%, demonstrating good accuracy and precision. Among the target compounds, ibuprofen was detected at the highest concentrations, reaching 0.60 μg L −1 in Mallegue and 0.50 μg L −1 in Mejerda, whereas ketoprofen and fenoprofen were detected at lower concentrations at the same sites. An ecotoxicological risk assessment based on LC50 values and risk quotient (RQ) calculations indicated low acute toxicity toward representative aquatic organisms and insignificant ecological risk (RQ <0.1) for all investigated NSAIDs at the measured environmental concentrations. These findings confirm the occurrence of NSAIDs in freshwater ecosystems in northwestern Tunisia and emphasize the importance of regular monitoring of emerging contaminants to support the protection of vulnerable Mediterranean aquatic environments.