Using Carbon Paste Electrode Modified with Ion Imprinted Polymer and MWCNT for Electrochemical Quantification of Methylmercury in Natural Water Samples

Abstract

Methylmercury (MeHg) is one of the most toxic organic mercury compounds found in the environment. The continuous exposure of human beings to this highly toxic compound may damage their nervous system. The present work reports the development and application of a novel electrochemical sensing technique for the quantification of MeHg using a modified carbon paste electrode with multi–walled carbon nanotubes (MWCNTs) combined with ion imprinted polymer, which is highly selective toward MeHg (CPE/MWCNTs/IIP–MeHg) detection. The ion imprinted polymer was synthesized using 2-mercaptobenzothiazole (MBT), acrylic acid (AA) and MeHg employed as ligand, functional monomer and template ion, respectively, and the synthesized material was characterized by Raman spectroscopy and SEM–EDX. Both the proposed and control sensors were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical measurements were carried out using differential pulse stripping voltammetry (DPSV), and a well–defined anodic peak observed at about +0.138 V (vs. Ag/AgCl) was recorded for MeHg. The application of the CPE/MWCNTs/IIP–MeHg sensor (which increased the charge transfer on the electrode surface) under the DPSV–based electrochemical method (which enhanced the signal intensity) made the detection technique highly sensitive and selective for the quantification of methylmercury. Under optimum experimental conditions, the proposed sensor exhibited a linear response range of 560–610 µg L−1 and a detection limit of 0.538 µg L−1, with acceptable relative error values ≤ 1% when applied for the detection of MeHg in real water samples.

Simultaneous Voltammetric Determination of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) Using a Modified Carbon Paste Electrode and Chemometrics

“…The presence of the MWCNTs at the structure of the modified electrode resulted in a charge transfer resistance (Rct) of 234.45 Ω in comparison to the MWCNT-CPE of Rct = 248.75 Ω. This result is in accordance with Figure 4 , where better electrocatalytic performance is observed as all anodic peaks move to lower potentials and an increase in the capacitive current is also observed [ 49 , 50 , 51 , 52 ]. In this sense, the presence of MWCNT increases the electrode’s surface area in contact with the sample, enhancing the measured analytical signal.…”

Ion-Selective Electrodes in the Food Industry: Development Trends in the Potentiometric Determination of Ionic Pollutants

“…However, portable and low-cost methods that do not require expensive detection systems are desirable. Within the past few years, nanomaterials, including sulphur-doped graphitic carbon nitride [98] and ion-imprinted polymers combined with multi-walled carbon nanotubes [99], have been developed for the specific detection of methylmercury through voltammetry with good selectivity. However, the potentiometric detection of this ion through potentiometric ion-selective electrodes has not been achieved yet.…”

“…This technology has been recently applied to simple anions such as chloride, with a material composition able to overcome standard ion-selective electrodes, such as the Nernst sensitivity limit [234]. Moreover, they can be applied to complex ions where ligands have not been reported yet, including methylmercury [99]. As such, the implementation of this technology could be key in the field.…”