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We developed a stripping chronopotentiometric method (constant current stripping analysis, CCSA) with a mercury film electrode for selenium quantification in seawater. A sensitivity and detection limit of 222 ms ng(-1) l and 4 ng l(-1) (50 pM), respectively, were accomplished for a 3-min electrolysis time. Compared to the other chronopotentiometric methods available for a single selenium measurement only in natural waters, our procedure exhibits a ten times better sensitivity. It, therefore, allows one to reach the current concentration thresholds found in coastal and oceanic waters (30-200 ng l(-1)). Moreover, a simple change in operating conditions enables one to also quantify Se(IV), a toxic dissolved species. With respect to the other electrochemical methods of current use, our procedure is beneficial because of its ease-of-use: it needs neither degassing step, nor catalyser.

An electrochemical method based on stripping chronopotentiometry (SCP) with a gold film electrode has been developed for determining arsenic in seawater. The detection limits were 0.053 ppb (0.71 nM) and 0.022 ppb (0.29 nM) for total inorganic As (As(T)) and As(III) after deposition times of 60 and 150 s, respectively. Compared to other stripping chronopotentiometric methods that use a gold macroelectrode to perform measurements of arsenic in seawater, the procedure described here exhibits better sensitivity and a fourfold shorter deposition time. Among the SCP methods, our procedure had proven its ability to analyse arsenic(III) in seawater. It therefore allows the concentrations of the various arsenic inorganic species in seawater—i.e. As(T), As(III) and As(V)—to be analysed. The proposed method is reliable, inexpensive and compact. It was successfully applied to the study of arsenic speciation along the salinity gradient of the Penzé estuary (NW France). [ABSTRACT FROM AUTHOR]

Abstract: A rapid electrochemical stripping chronopotentiometric procedure to determined sulfide in unaltered hydrothermal seawater samples is presented. Sulfide is deposited at −0.25V (vs Ag/AgCl, KCl 3M) at a vibrating gold microwire and then stripped through the application of a reductive constant current (typically −2μA). The hydrodynamic conditions are modulated by vibration allowing a short deposition step, which is shown here to be necessary to minimize H2S volatilization. The limit of detection (LOD) is 30nM after a deposition step of 7s. This LOD is in the same range as the most sensitive cathodic voltammetric technique using a mercury drop electrode and is well below those reported previously for other electrodes capable of being implemented in situ. [Copyright &y& Elsevier]

Abstract: The frontal cascade ultrafiltration (UF) technique in conjunction with stripping chronopotentiometry (SCP) has been evaluated for determining the colloidal distribution of Cu, Pb and Cd in estuarine waters. Metallic concentrations in seven size fractions (0.45μm–0.22μm; 0.22μm–300kDa; 300–50kDa; 50–30kDa; 30–10kDa; 10–5kDa; <5kDa) were determined with the aim to investigate their changes along the salinity gradient of the Penzé system (NW France). These data, completed by analysis of the total dissolved metals at 10 stations over the whole freshwater–seawater mixing zone, provided some insights in the removal and addition processes that affect Cu, Pb and Cd in estuaries. [Copyright &y& Elsevier]