Caramelized carbonaceous shell-coated γ-Fe₂O₃ as a magnetic solid-phase extraction sorbent for LC-MS/MS analysis of...

Carbonaceous shell-coated γ-Fe₂O₃ nanoparticles (γ-Fe₂O₃@CNM) were synthesized from glucose caramelization and used as a novel magnetic solid-phase extraction medium for malachite green and crystal violet in environmental water. Malachite green and crystal violet were absorbed on to γ-Fe₂O₃@CNM by electrostatic and π-interactions. The morphologies, pore structures, surface functional groups, and magnetic properties of γ-Fe₂O₃@CNM were characterized by TEM, FTIR, hysteresis regression, Brunauer-Emmet-Teller analysis, zeta potential, XPS, and XRD. The magnetic solid-phase extraction procedure was optimized by extraction pH, absorption time, desorption solvent, and desorption time. The absorption capacities (q_max values) for malachite green and crystal violet were 34.2 and 27.9 mg g^-1, respectively. After magnetic solid-phase extraction, malachite green and crystal violet were determined by LC-MS/MS. The analytical method was validated with a linear range of 0.02-20 ng mL^-1, enrichment factor of 25.8 and 25.4, method detection limit of 0.004 ng mL^-1, and intra-day precisions of 2.1% and 2.6% for malachite green and crystal violet, respectively. The relative recovery was found to be 73.4-101.5% for malachite green and 83.1-102.7% for crystal violet upon the application of the magnetic solid-phase extraction method to real water samples from lake, spring, sea, fishpond, and industrial waste. Graphical abstract Caramelized-carbon-coated magnetic nanoparticles are used as novel extraction medium based on electrostatic and π-interactions. It is porous, amphiphilic, electronegative, magnetically strong, and features abundant absorption site. These characteristics stimulate mass transfer and result in a useful MSPE method in environmental analysis.