Mercury‐Free Detection of Europium (III) at a Glassy Carbon Electrode Modified with Carbon Nanotubes by Adsorptive Stripping Voltammetry

A multi-wall carbon nanotubes (MWCNTs) and Nafion composite film-modified glassy carbon electrode (GCE) is described for the detection of europium (III) by differential pulse adsorptive stripping voltammetry. In pH 4.2 NaAc-HAc buffer solution, Eu3+ is first exchanged by Nafion and absorbed on the surface of MWCNTs film. The accumulated Eu3+ then undergoes a one-electron reduction around -0.7 V during the potential sweep from -0.1 to -1.0 V. The MWCNTs-Nafion film significantly improves the sensitivity of Eu3+ determination compared with a bare GCE and a Nafion-coated GCE. The differential pulse stripping voltammetric (DPSV) signal changes linearly with the concentration of Eu3+ in a wide range from 4.0 x 10(-8) to 1.0 x 10(-4) M. The detection limit is estimated to be 10 nM for 60 s accumulation at -0.1 V. Lots of inorganic ions and all of the other rare earth ions do not give characteristic voltammetric responses in the developed operation. The sensitivity and stability of this MWCNTs-Nafion GCE has demonstrated its application for a rapid and mercury-free detection of trace Eu3+ in NIES CRM No. 8 vehicle exhaust particulates.