Novel in situ Bi−Sb‐Film Electrodes for Trace Heavy Metal Analysis

Abstract

AbstractThis work reports on new in situ formed Bi−Sb‐film glassy carbon electrodes (Bi−SbFEs) with different Bi(III):Sb(III) mass concentration ratios (1 : 9, 2 : 8, 3 : 7, 4 : 6, 5 : 5, 6 : 4, 7 : 3, 8 : 2, 9 : 1) and at two different total mass concentrations of Bi(III) and Sb(III), i. e. 0.5 and 1.0 mg/L. The analytical performance of these Bi−SbFEs was compared with Bi‐film (BiFE) and Sb‐film (SbFE) electrodes in 0.1 M acetate buffer solution. All combinations of Bi−SbFEs were selective for Zn(II), Cd(II), and Pb(II) detection. Bi−SbFEs showed linear concentration ranges for Zn(II), Cd(II), and Pb(II) substantially wider than that for BiFE. Moreover, the method's sensitivities can be substantially improved by using different Bi−SbFEs compared with BiFE and SbFE. Most of the Bi−SbFE methods provided satisfactory recovery for Cd(II) determination, many of them also for Pb(II), whereas for Zn(II) only a few methods provided recovery values within the 80.0–120.0 % recovery range. The precision of different Bi−SbFEs were satisfactory for Pb(II) and Cd(II) with an RSD lower than 20.0 %. Accumulation time optimisation resulted in lower LOD and LOQ, higher sensitivity. Finally, electrochemical impedance spectroscopy was employed for the first time to characterise the electroanalytical behaviour of an SbFE. The latter analysis was employed to compare the electrode's properties with pure BiFE and pure GCE, and to show when the system is under a kinetic‐ and/or diffusion‐controlled process.