Flow electroanalytical system based on cyclam-modified graphite felt electrodes for lead detection

Coupling of Anodic Stripping Voltammetry with Sampled-Current Voltammetry on an Electrode Array: Application to Lead Detection

Electrochemical detection systems are very promising for pollution monitoring owing to their easy miniaturization and low cost. For this purpose, we have recently developed a new concept of device based on Electrodes Array for Sampled-Current Voltammetry (EASCV), which is compatible with miniaturization and portability. In this work, to improve the sensitivity of the analytical method, we added a preconcentration step before EASCV analysis, combining sampled-current voltammetry with anodic stripping voltammetry. Lead was chosen as analyte for this probe of concept owing to its high toxicity. The conditions for electrodeposition of lead on gold were optimized by means of under potential deposition. Current intensities 300 times higher than with linear sweep anodic stripping voltammetry were obtained, showing the interest in the method. The value of the sampling time directly affected the sensitivity of the sensor given by the slope of the linear calibration curve. The sensor exhibited a limit of detection of 1.16 mg L⁻¹, similar to those obtained with linear sweep anodic stripping voltammetry.

Electrochemical platform based on nitrogen-doped graphene/chitosan nanocomposite for selective Pb2+ detection

A novel nanocomposite was developed and used for trace determination of Pb²⁺ cations from aqueous solutions. The nanocomposite was obtained by the association of N-doped graphene (N-Gr) with a biocompatible polymer, namely chitosan (Ch). The characterization of the new nanocomposite material (Ch-N-Gr) was performed using TEM, STEM-EDX, SEM, XRD and XPS techniques. Compared with the bare gold electrode (GE) a remarkable enhancement of the voltammetric response of the modified electrode (Ch-N-Gr/GE) was always observed. Using the Ch-N-Gr/GE, the Pb²⁺ voltammetric response showed a pair of well defined, quasi-reversible anodic and cathodic peaks, with the peak potentials located at about -0.59 V and -0.69 V, respectively. The calibration curves were obtained over a large linear range, from 10^-7 to 10^-4 M Pb²⁺ concentration. Under optimized conditions, the detection limit was found to be 6.64 × 10^-8 M. The effect of several interfering species (such as other metallic cations or organic compounds of various concentrations) on the determination of Pb²⁺ concentration was also studied, and the results proved the selectivity of the proposed modified electrode. The validity and effectiveness of the method was further confirmed by trace determination of Pb²⁺ in real samples.

Anodic stripping voltammetry with graphite felt electrodes for the trace analysis of silver

Graphite felt electrodes, costing less than one British pence each, are used as sensors for silver with a low limit of detection and large linear range.

Evaluation of Hydrophilized Graphite Felt for Electrochemical Heavy Metals Detection (Pb2+, Hg2+)

Hydrophilized graphite felt has been used,for the first time, for the electrochemical detection of Hg2+ions both as single metal species and via its simultaneous detection with Pb2+. To do so, square wave voltammetry (SWV) method was developed with alginate modified graphite felt as working electrode. The structure of the graphite felt such as its high porosity and specific surface area coupled with its good electrical conductivity allows achieving large peak currents via the SWV method, suggesting that the alginate coating helps to preconcentrate metals at the carbon surface. The as-described electrode has low cost, it is easy to manipulate, and the electrochemical analysis can be performed by simple immersion of the felt in the metal solution.