Magnetic molecularly imprinted polymers prepared by reversible addition fragmentation chain transfer polymerization...

Magnetic molecularly imprinted polymers (MMIPs) combine nanotechnology and molecular imprinting technology to offer selective and tunable enrichment for water analysis. In this paper, a selective sorbent was prepared by surface polymerization onto magnetic Fe₃O₄@SiO₂ nanoparticles through reversible addition fragmentation chain transfer (RAFT) polymerization. The MMIPs were used for dispersive solid phase extraction (DSPE) of 16 PAHs as priority pollutants in aqueous matrices. After preconcentration, the analysis was performed using gas chromatography with an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS). The extraction method is based on the dispersion of MMIPs in an aqueous sample using an ultrasonic bath which provides rapid equilibrium of analytes between the sorbent and sample solution. The enriched analytes were retrieved by collecting MMIP particles and desorbed into an organic solvent before instrumental analysis. A design of experiment (DOE) approach was applied to optimize several extraction parameters including the mass of MMIPs, the sample volume, salt addition, collection time, desorption volume, and desorption time. A fractional factorial design (FFD) (2^6-2) was performed to assess the influence of the selected factors on the extracted amount of analytes. The most effective factors including the mass of MMIPs, the volume of sample solution, and salt content was further investigated using central composite design (CCD) and yielded quadratic models between dependent and independent variables. The optimum conditions of DSPE obtained by desirability function (DF) were employed for preconcentration of PAHs in water samples. The evaluation showed that the MMIPs provide higher extraction efficiency compared to nanoparticles such as Fe₃O₄, Fe₃O₄@SiO₂ and non-imprinted polymer, demonstrating the creation of selective recognition binding sites at the surface of magnetic nanoparticles. The LODs and LOQs ranged from 1 to 100 pg mL^-1 and 2 to 200 pg mL^-1, respectively. Finally, the MMIP-DSPE method was successfully applied for preconcentration and trace quantification of PAHs in real samples such as produced water and river water samples.