Investigation of the adsorption mechanism and preconcentration of sulfonamides using a porphyrin-functionalized Fe₃O₄-graphene oxide nanocomposite.

In this work, a novel type of porphyrin-functionalized Fe3O4-graphene oxide (TCPP/Fe3O4-GO) nanocomposite was synthesized. The adsorption mechanism of the prepared TCPP/Fe3O4-GO material was investigated and predicted. The π-π stacking and electrostatic attraction between the positively charged analytes and the negatively charged porphyrin-functionalized Fe3O4-GO accelerated the electron transfer between the materials. In addition, to investigate the preconcentration of the prepared TCPP/Fe3O4-GO, it was used as a magnetic solid-phase extraction adsorbent for the preconcentration of seven sulfonamides (SAs) from environmental water samples. Parameters that significantly affected the extraction of the SAs onto the sorbent, such as the elution solvent, extraction time and elution time, were optimized. Under the optimal conditions, the SAs in the environmental water samples were effectively detected. The linear range for the seven SAs was 0.5-20 μg mL(-1), and the limits of detection for all seven SAs were 0.2 μg mL(-1). Good reproducibility was obtained, along with relative standard deviations that ranged from 0.01 to 8.25%. The present method was applied to the determination of SAs in tap and river water samples, and the recoveries were satisfactory (83.7-116.7%).