Synthesis and characterization of a magnetic molecularly imprinted polymer for the selective extraction of nicotine and cotinine from urine samples followed by GC-MS analysis

Abstract

A magnetic molecularly imprinted polymer (MMIP) was synthesized, characterized and used in the selective extraction of nicotine and cotinine from urine samples, followed by GC-MS analysis. Fe₃O₄ nanoparticles were prepared by the co-precipitation method, silanized/stabilized with tetraethyl orthosilicate and functionalized with 3-(trimethoxysilyl)propyl methacrylate. The MMIP was prepared on the magnetic nanoparticle surface, using nicotine as the template and methacrylic acid as the functional monomer. The material was characterized by scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectrometry and thermogravimetry, where all the synthesis steps were confirmed. The nanoparticles were used in the dispersive solid phase extraction of nicotine and cotinine from human urine samples, and the extracts were analyzed by GC-MS. The analytical curves ranged from 0.1 to 3.0 mg L⁻¹ (r > 0.99), with a limit of quantification (LOQ) of 0.1 mg L⁻¹ for both analytes. The intra- and inter-day precisions were less than 20% for the LOQ and less than 15% for the other points; whereas the intra- and inter-day accuracies were within ±9%. The method was successfully employed to analyze nicotine and cotinine from four real smokers' urine samples.