Submersible voltammetric probes for <i>in situ</i> real-time trace element measurements in surface water, groundwater and sediment-water interface

A summary of the state of the art in the development of two submersible voltammetric probes performed by us to allow continuous, real-time monitoring of trace elements (Cu(II), Pb(II), Cd(II), Zn(II) and Mn(II), Fe(II)) in natural aquatic ecosystems is given. The first one, called the voltammetric in situ (VIP) profiling system, allowed in situ measurements in surface water and groundwater down to 500 m. Its construction required the development of: (i) a gel-integrated, either single or interconnected, array microsensor, (ii) a submersible probe and (iii) hardware, firmware and software for control of the whole system: i.e. data transmission and acquisition, data processing and maintenance operations. The second system, called the sediment-water interface voltammetric in situ profiling (SIVIP) system, has been developed to allow real-time, high spatial resolution trace elements concentration profile measurements at the sediment-water interface. Its construction required the development of: (i) a gel-integrated microsensor array with 64 individually addressable lines, (ii) a voltammetric probe based on powerful double multiplexing system and single potentiostat allowing simultaneous measurements over the 64 sensor lines, and (iii) hardware, firmware and software for control of the whole system. A general description of both systems as well as examples of laboratory characterization and/or field applications are reported

A Novel Voltammetric Probe with Individually Addressable Gel-Integrated Microsensor Arrays for Real-Time High Spatial Resolution Concentration Profile Measurements

In this article, the development of a novel voltammetric system for real-time, high spatial resolution trace element concentration profile measurements at the sediment-water interface, or other interfaces, is reported. The heart of this system is a novel gel-integrated Hg-plated Ir-based 64 individually addressable microsensor arrays. The gel membrane minimizes fouling problems and insures high stability of the Hg semidrops. Measurements were performed simultaneously over the 64 lines using a powerful multiplexing system and a single potentiostat. The voltammetric probe and sensor have been described in detail. This voltammetric system has been characterized by running both cyclic voltammetry (CV) in hexacyanoferrate(III) solution using the gel-integrated Ir-based microsensor and square-wave anodic stripping voltammetry (SWASV) in Pb(II) and Cd(II) solution using the gel-integrated Hg-plated Ir-based microsensor. The results showed that reproducible and reliable simultaneous measurements can be obtained over the 64 individually addressable lines even with fast dynamic techniques such as SWASV. Moreover, theoretical and experimental data were in good agreement. Profiling capability has also been demonstrated