Hydrazide functionalized magnetic nanoparticles for specific extraction of N‐terminal serine and threonine peptides

In this study, we present hydrazide functionalized magnetic nanoparticles as a sorbent prepared by a new and facile method. Scanning electron microscope and Fourier transform infrared were used for characterizing the synthesized nanoparticles. The ability of the sorbent to extract N‐terminal serine and threonine peptides was evaluated. The peptides were modified by oxidation of the hydroxyl group in the 1,2‐amino alcohol structure before extraction. These aldehyde‐forms of peptides were specifically bonded to the hydrazide groups of the sorbent. The formed hydrazone bonds were cleaved in the presence of hydroxylamine reagent. Finally, the oximated peptides were released and quantified with a high‐performance liquid chromatography–diode array spectroscopy. The effects of experimental parameters including extraction time, elution time and elution volume on extraction efficiency were also investigated. The required time for the extraction process to reach equilibrium and elution time was only 8 h. The adsorption efficiency of the sorbent was 79 and 77% for peptides with N‐terminal serine and threonine, respectively. The sorbent showed good specificity for extracting the peptides. In addition, the extraction efficiency of the sorbent remained constant in the presence of a non‐N‐terminal serine and threonine peptide as interference.