Superparamagnetic surface molecularly imprinted nanoparticles for sensitive solid-phase extraction of tramadol from urine samples

A rapid, selective, sensitive and accurate method based on superparamagnetic molecularly imprinted polymer nanoparticles (MMIPNPs) was developed for the determination of tramadol (TRA) in human urine samples. The MMIPNPs were prepared by coating SiO2–Fe3O4 nanoparticles with polyaminoimide homopolymer and TRA as the template. The prepared MMIPNPs adsorbent was characterized by TEM, FT-IR, XRD and magnetometry. TEM images show that the Fe3O4 nanoparticles are well-enwrapped by the SiO2 shell and further by an MIP layer. The prepared magnetic adsorbent is well dispersed in water and can be easily separated magnetically from the medium after loading with the adsorbate. Various parameters affecting the extraction efficiency of the MMIPNPs have been evaluated. The extracted TRA could be easily desorbed with a mixture of methanol and acetic acid and determined spectrophotometrically at 272 nm. A linear dynamic range was established from 3.0 to 200.0 ng mL−1 of TAR and the limit of detection was found to be 1.5 ng mL−1. The proposed method was successfully applied for the determination of TRA in human urine samples.