Fe₃O₄/GO Magnetic Nanocomposite—A Selective Probe for Simultaneous Detection of Carbofuran and Carbendazim Residues by Electrochemistry and LDI-MS

Fe₃O₄/GO magnetic nanocomposite is synthesized and applied as a selective probe for simultaneous detection of pesticides (carbofuran and carbendazim) verifying by the high binding energies calculated by density functional theory. Electrochemistry and LDI-MS are selected for screening and quantitative determination of these pesticides. Fe₃O₄/GO modified on electrode enhances electrocatalytic activity of carbofuran and carbendazim and their oxidation peak currents linearly increase upon the increase of their concentrations in a range of 1- 250 μM with LODs of 0.06 μM and 0.18 μM for CBF and CBZ, respectively. For LDI-MS, after magnetic separation, CBF and CBZ bound with Fe₃O₄/GO are readily ionized leading to high ion abundance with a linear range of 1- 1000 μM. Thus, using Fe₃O₄/GO magnetic nanocomposite along with our detection platform is effective to cover the required detection level of CBF and CBZ residues in the fruits, which are 0.45 μM and 2.5 μM, respectively. Ultimately, Fe₃O₄/GO bound with CBF and CBZ spiked in pear are successfully visualized by imaging-MS verifying the distribution of these pesticides in real pear peel samples.