A Sensitive Electrochemical Sensor for Hydroxylamine Determination: Using Ionic Liquids and Magnetic Core–shell Fe3O4@TiO2/MWCNT Nanocomposite and 2-(4-Oxo-3-phenyl-3,4-dihydroquinazolinyl)-N′-phenyl-Hydrazinecarbothioamide as Mediator

A sensitive electrochemical sensor for determination of hydroxylamine has been introduced. This sensor profits by 2-(4-Oxo-3-phenyl-3,4-dihydroquinazolinyl)-N′-phenyl-hydrazinecarbothioamide (2PHC) as mediator and magnetic core–shell Fe3O4@TiO2/MWCNT nanocomposite and ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) to improve the working electrode behavior. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry, and differential pulse voltammetry (DPV) are used to study of the suitability of 2PHC, at the surface of modified electrode, as a mediator for the electrocatalytic oxidation of hydroxylamine in aqueous solutions. The electrocatalytic peak current of hydroxylamine oxidation shows a linear dependence on hydroxylamine concentration in the range of 0.1–500.0 μM, by DPV in optimized conditions at pH 7.0. The detection limit (3σ) was obtained 52.0 nM. Electrochemical parameters such as electron transfer coefficient, α and diffusion coefficient, D, are also determined. The proposed method was successfully applied as a highly sensitive, selective, simple, and precise method for hydroxylamine determination in the water samples.