Bogdan Feier

Flow electrochemical analyses of zinc by stripping voltammetry on graphite felt electrode

A flow sensor for trace analysis of zinc, using graphite felt as working electrode is reported here. A flow cell, well-adapted to 3-D porous electrodes and capable to do both the preconcentration step at a cathodic potential and the stripping of the zinc was successfully developed. It was demonstrated that this cell allows to obtain better electrochemical signals for Zn(2+) compared to a standard three-electrodes cell and that the percolation during accumulation increases the kinetics of electrodeposition. The influence on Zn(2+) signal of the deposition potential, the time of deposition and the flow rate was studied. The resulting sensor shows a linear response towards Zn(2+) with a linear range of 10(-6)-10(-4)M and a limit of detection of 5×10(-7) M for an analysis time of 5 min. The interferences study showed that the Cr(3+), Pb(2+), Cd(2+) ions have a small effect on the Zn electrochemical signal, whereas Fe(3+), Cu(2+), Co(2+) and Ni(2+) ions strongly influence it. The electrode was tested on real samples (tap water spiked with Zn(2+), food supplement) with a good recovery by applying the standard addition method.

Electrochemical behaviour of several penicillins at high potential

Electrochemical oxidation at high potential, using a bare boron-doped diamond electrode as the working electrode was evaluated for five penicillins: oxacillin, penicillin V, penicillin G, ampicillin and amoxicillin. Even though the electrochemical oxidation is expected to occur at the common penicillin core, the five molecules exhibited different electrochemical behaviour, even after alkaline or acid hydrolysis. Based on anodic oxidation at high potential, a simple electrochemical method was developed for the detection of oxacillin by differential pulse voltammetry. Different electrode materials and electrode modifications were tested, with the best results being obtained with the unmodified boron-doped diamond electrode. The developed method allows a selective detection of oxacillin, with low influence from common interferents and is sensitive enough to be successfully applied to oxacillin detection from pharmaceutical, biomedical and environmental samples. The anodic oxidation of penicillins was successfully adapted for flow injection analyses, with sensitive and reproducible successive analyses of oxacillin, at different concentrations.

SPR based hybrid electro-optic biosensor for β-lactam antibiotics determination in water

The present work aims to provide a hybrid platform capable of complementary and sensitive detection of β-lactam antibiotics, ampicillin in particular. The use of an aptamer specific to ampicillin assures good selectivity and sensitivity for the detection of ampicillin from different matrice. This new approach is dedicated for a portable, remote sensing platform based on low-cost, small size and low-power consumption solution. The simple experimental hybrid platform integrates the results from the D-shape surface plasmon resonance plastic optical fiber (SPR-POF) and from the electrochemical (bio)sensor, for the analysis of ampicillin, delivering sensitive and reliable results. The SPR-POF already used in many previous applications is embedded in a new experimental setup with fluorescent fibers emitters, for broadband wavelength analysis, low-power consumption and low-heating capabilities of the sensing platform.

Electrochemical Sensors in Environmental Analysis

Monitoring the environment for contaminants is nowadays closely related with our whole planet and human health. Due to the large variety of pollutants and required environmental analysis, the need for rapid, sensitive, decentralized analysis is continuously increasing. Electrochemical sensors could be well suited for this need but also could complement standard analytical techniques validated for some environmental analysis. Environmental analysis includes atmospheric analysis, groundwater and surface water analysis, ocean monitoring, soil analysis, agriculture, and food and even pharmaceutical monitoring.