Hg(II) trace electrochemical detection on gold electrode: Evidence for chloride adsorption as the responsible for the broad baseline

Investigations were performed in order to clarify the origin of the broad baseline observed during Hg(II) trace electrochemical detection on gold electrode in the presence of Cl- anions. The influence of Cl- concentration on the shape of the voltammograms was studied in the presence and in the absence of Bovine Serum Albumin (BSA) in order to bring out adsorption/desorption processes. On the basis of these experiments, and contrary to what has been proposed by several authors in the literature, it was proved that the broad baseline does not result from calomel (Hg2Cl2) formation but is rather related to an interaction between Cl- and polycrystalline Au electrode surface. The evolution of the shape of the baseline was also studied in the presence of other halide anions, namely F-, Br-, and I-. The latter two were found to induce a broad baseline similar to that recorded in the presence of Cl-. Finally, it was shown that BSA addition is not suitable for Hg(II) detection since it prevents Hg(0) deposition onto the electrode surface

Influence of the gold nanoparticles electrodeposition method on Hg(II) trace electrochemical detection

Gold nanoparticles (AuNPs) were deposited on Glassy Carbon (GC) substrate by using three electrochemical techniques: Cyclic Voltammetry (CV), Chronoamperometry (CA) and Potentiostatic Double-Pulse (PDP). For each electrodeposition method, the resulting AuNPs-modified electrodes were characterized by CV in H2SO4 and Field Emission Gun Scanning Electron Microscopy (FEG-SEM). CA was found to be the best electrodeposition mode for controlling the morphology and the density of AuNPs. The modified electrodes were used for low Hg(II) concentration detection using Square Wave Anodic Stripping Voltammetry (SWASV). AuNPs obtained by CA afforded the best amperometric response while involving the lowest amount of charge during the electrodeposition step (QAu(III)). This analytical response is correlated to both the smallest particle size (ca. 17 nm in diameter) and the highest particle density (332 particles μm−2), thus displaying high electrode effective surface area. In these optimal conditions, using a Hg(II) preconcentration time of 300 s, the nanosensor array exhibited a linearity range from 0.80 to 9.9 nM with a sensitivity of 1.16 μA nM−1. A detection limit of 0.40 nM (s/n = 3) was reached

Intérêt de la chromatographie liquide d'interactions hydrophiles pour l'analyse de composés polaires dans des matrices complexes

Peer reviewe

Production line real time near infrared (NIR) monitoring

Peer reviewe

Château-Landon – La prairie du Pont de Dordives

Le site subaquatique étudié au lieu-dit cadastral « La Prairie du Pont de Dordives » est situé dans le lit du Loing, affluent de la Seine. À ce niveau passe une voie romaine, le « chemin de César », allant d’Orléans à Sens. En 1997 et 1998, deux saisons de sondage ont mis en évidence un important haut-fond empierré recouvert de moins d’un mètre d’eau, limité par 25 pieux formant deux lignes. La présence d’un entrelacs de branchages et d’autres bois entre les pieux et les pierres calcaires sem..