A new extraction phase based on hydrogel disks of polyvinyl alcohol (PVOH) and pectin was proposed, characterized and evaluated for the extraction of six steroidal hormones (estriol, estrone, 17β-estradiol, 17α-ethinylestradiol, progesterone, and testosterone) in aqueous samples with subsequent determination by gas chromatography-tandem mass spectrometry (GC-MS/MS) after the derivatization procedure. The developed extraction procedure was based on the solid phase extraction (SPE) technique, but employed hydrogel as the sorbent phase. The effects of several parameters, including the amount and composition of the sorbent phase, pH, sample volume, flow rate, and gel swelling over the extraction efficiency, were evaluated. Gels with lower swelling indexes and larger amounts of sorbent ensured higher extraction yields of analytes. The main benefits of using the PVOH/pectin-based hydrogel as the extraction phase are the ease of synthesis, low-cost preparation, and the possibility of reusing the extraction disks. Limits of quantification of 0.5 μg L⁻¹ for estrone and 17β-estradiol, and 1 μg L⁻¹ for testosterone, 17α-ethinylestradiol, progesterone, and estriol were obtained. Accuracy values ranged from 80% to 110%, while the inter-assay precision ranged from 0.23% to 22.2% and the intra-assay from 0.55% to 12.3%. Since the sorbent phase has an amphiphilic character, the use of hydrogels is promising for the extraction of medium-to-high polarity compounds.

Hydrogels are smart-swelling 3D structures capable of incorporating/expelling water while maintaining their structures. When combined with electroactive materials, such as conducting polymers, the resulting composite may present tunable properties. Herein, the preparation and characterization of alginate-polypyrrole composite hydrogels is described using chemical polymerization to form polypyrrole inside and around alginate beads, employing two simple protocols. These materials were qualitatively tested as extraction phases, using the solid-phase extraction technique, for the pre-concentration of contaminants of emerging concern (atrazine, caffeine, and progesterone). Compared to alginate alone, the composite materials showed a modified extraction capacity, especially for the extraction of progesterone. It was shown that the alginate matrix also contributes to the extraction, not only acting as a support but also as an active extraction media, evidencing a good combination of materials.