Analytical Determination of Emerging Contaminants in Wastewater by Low-Volume Solid-Phase Extraction and Application to Microalgae-Based Treatment

Endocrine-disrupting compounds (EDCs) are frequently detected in wastewater and aquatic environments because of their incomplete removal in conventional wastewater treatment plants. Evaluating alternative treatment technologies, including microalgae-based systems, requires analytical methods suitable for low-volume samples. In this work, a solid-phase extraction (SPE) procedure coupled with high-performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the simultaneous determination of methylparaben (MeP), propylparaben (PrP), butylparaben (BuP), benzophenone (BP), bisphenol A (BPA) and estrone (E). The method combines relatively low sample volume and limited eluent consumption with the analysis of six chemically diverse EDCs in biomass-containing samples using accessible HPLC-DAD instrumentation. Sorbent mass, sample volume, elution volume, and pH were evaluated experimentally, with Random Forest used for exploratory multivariable interpretation. Selected conditions were a 500 mg cartridge, 30 mL of sample volume at pH 7 and 2 mL methanol elution volume. The method showed satisfactory linearity (R2 ≥ 0.98), limits of quantification between 1.67 and 6.67 ppb, and stable recoveries across the evaluated concentration range. Applicability was demonstrated in a Scenedesmus sp.-based system. AGREEprep assessment yielded a score of 0.34. The developed SPE method provides a low-volume approach for monitoring EDCs in microalgae-based wastewater treatment systems.