Polyvinyl Alcohol/Pectin-Based Hydrogel as Sorptive Phase for the Determination of Freely Dissolved Parabens in Urine Samples by LC-DAD

An extraction phase based on hydrogel disks of polyvinyl alcohol and pectin was developed, characterized, and evaluated for the extraction of four endocrine disruptors (methylparaben, ethylparaben, propylparaben and butylparaben) in free form in human urine samples with subsequent determination by liquid chromatography coupled with a diode array detector (LC-DAD). The proposed hydrogel showed easy synthesis, was made of low-cost and non-toxic polymers, and showed that it has an amphiphilic character. Gels with lower swelling indexes (175%) and more concentrated dispersions of polymers (P20PC2.0) showed lower relative standard deviation (RSD) values. Under optimized solid phase extraction (SPE) conditions, the LC-DAD method presented limits of quantification of 0.1 µg mL-1, accuracy values ranged from 101.3 to 118.2%, while the inter-assay precision ranged from 1.5 to 17.4%. In addition, the polyvinyl alcohol (PVOH)/pectin-based material presented the possibility of reuse of at least 15 times, without presenting carryover effect and physical degradation. In this way, the hydrogel shows promise for the extraction of organic compounds with different polarities in biological matrices.