Hierarchical porous nanostructured polypyrrole-coated hydrogel beads containing reduced graphene oxide and magnetite nanoparticles for extraction of phthalates in bottled drinks

A hierarchically porous polypyrrole-coated nanostructured composite of reduced graphene oxide and magnetite nanoparticles (PPy-rGOx-Fe3O4) incorporated into alginate hydrogel microspheres was synthesized and applied as a magnetic solid phase extraction adsorbent. The double network porous nanostructure of the composite hydrogel was created by CO2 produced from the reaction of hydrochloric acid with the CaCO3 in the hydrogel. The developed hydrogel microsphere was characterized and evaluated for the extraction and enrichment of phthalates. Several parameters that could potentially affect the extraction efficiency of the developed hydrogel microspheres were investigated. The developed method provided a wide linear range from 0.005 to 500 μg L−1 for dibutyl phthalate, 0.01 to 500 μg L−1 for diethyl phthalate, benzylbutyl phthalate and bis(2-ethylhexyl) phthalate, and 0.02 to 500 μg L−1 for dimethyl phthalate and di-n-octyl phthalate. Low limits of detection were obtained in the range of 0.005-0.01 μg L−1. The developed adsorbent was successfully used to extract phthalates in bottled water and beverages and the recoveries achieved were between 87.5 and 99.1%. The developed adsorbent can be used as an alternative rapid, convenient and cost effective adsorbent for the enrichment and analysis of trace phthalates.