Desenvolvimento de dispositivo polimérico monolítico de POLI(TMPTA-EDMA-MAA) impresso molecularmente visando a extração de ceftiofur sódico em amostras de leite

Abstract

Ceftiofur sodium is an antibiotic widely used in veterinary medicine for the treatment of bacterial infections. However, its use, especially in the treatment of mastitis in dairy cows, can result in residues in the milk, representing a potential risk to consumer health. In this context, sample preparation plays a fundamental role in the pre-concentration and extraction of analytes from complex matrices such as milk, being a critical step in chemical analysis because it is associated with most experimental errors and the total analysis time. Among the available techniques, pipettetip solid-phase extraction (PT-SPE) stands out as a miniaturized and portable approach compared to conventional solid-phase extraction. However, commercially available particulate sorbents for this technique have low selectivity and reproducibility, and require filters in the tips, which increases the cost of the device. Replacing them with monolithic sorbents prepared directly inside the tip eliminates the need for filters and allows for greater liquid permeability due to their macroporous structure. Thus, this study aimed to optimize and characterize a monolithic, hierarchically porous extraction phase based on polymethacrylates, targeting the selective extraction of ceftiofur. These sorbents can be functionalized by molecular imprinting (MIP), which ensures their selectivity. The organic monoliths were polymerized in situ in disposable pipette tips from trimethylolpropane triacrylate (TMPTA), ethylene glycol dimethacrylate (EDMA), and methacrylic acid (MAA) monomers, using 2,2’-azobisisobutyronitrile as a radical initiator, at 60 °C for 20 h. Optimization was performed with isopropanol as a pore-forming solvent, followed by substitution with N,N-dimethylformamide in the molecular imprinting process. The MIP monoliths presented a BET surface area of 114.08 m2 ·g-1 , an average pore diameter of 18 nm (mesoporous), high total porosity (~67%), and thermal stability of ~350 °C. Extraction efficiency was evaluated by HPLC-DAD, with an impression factor of 7.0 compared to non-imprinted monoliths (NIP). Thus, the poly(TMPTA-MAA-EDMA) MIP monoliths proved to be suitable selective sorbents for application in the PT-SPE technique for selective microextraction of the antibiotic in dairy matrices.