Electrochemical techniques anodic stripping voltammetry

Electrochemical techniques anodic stripping voltammetry (ASV) and cathodic stripping voltammetry (CSV) for determining trace elements, and potentiometric sensors for determining dissolved gases (C02, N02, S02, NH3, H2S, HCN, and HF) as well as chloride, fluoride, cyanide, and sulfide. 

Anodic stripping voltammetry (ASV). This is an electrochemical technique in which the element to be analyzed is first deposited on an electrode and then redissolved, that is, stripped, from the electrode to form a more concentrated solution. For example, a drop of mercury hanging from a platinum electrode in a solution containing the species to be measured has been used as the deposition electrode. A potential slightly more negative than the half-wave potential for the ion of interest is applied to deposit the element on the electrode. After deposition of the metal for a given... 

Cathodic stripping voltammetry — Refers to a family of procedures involving a - preconcentration by electrochemical oxidation (or reduction) of the analyte (or a salt or derivative of the analyte) onto (or into) the working electrode prior to its direct or indirect determination by means of an electroanalytical technique (see also -> stripping voltammetry, and - anodic stripping voltammetry) [i]. During the stripping step, i.e.,... 

Various spectroscopic techniques such as flame photometry, emission spectroscopy, atomic absorption spectrometry, spectrophotometry, flu-orimetry, X-ray fluorescence spectrometry, neutron activation analysis and isotope dilution mass spectrometry have been used for marine analysis of elemental and inorganic components [2]. Polarography, anodic stripping voltammetry and other electrochemical techniques are also useful for the determination of Cd, Cu, Mn, Pb, Zn, etc. in seawater. Electrochemical techniques sometimes provide information on the chemical species in solution. 

Analytical techniques used for clinical trace metal analysis include photometry, atomic absorption spectrophotometry (AAS), inductively coupled plasma optical emission (ICP-OES), and inductively coupled plasma mass spectrometry (ICP-MS). Other techniques, such as neutron activation analysis (NAA) and x-ray fluorescence (XRF), and electrochemical methods, such as anodic stripping voltammetry (ASV), are used less commonly For example. NAA requires a nuclear irradiation facility and is not readily available and ASV requires completely mineralized solutions for analysis, which is a time-consuming process. 

For chemical monitoring, a list of priority substances has been established that includes metals such as cadmium, lead, and nickel. As far as metals are concerned, voltammetric techniques and more precisely electrochemical stripping analysis has long been recognized as a powerful technique in environmental samples. In particular, anodic stripping voltammetry (ASV) coupled with screen-printed electrodes (SPEs) is a great simplification in the design and operation of on site heavy metal determination in water, for reasons of cost, simplicity, speed, sensitivity, portability and simultaneous multi-analyte capabilities. The wide applications in the field for heavy metal detection were extensively reviewed (Honeychurch and Hart, 2003 Palchetti et al., 2005). 

Other versatile and sensitive techniques for determination of metal ions in water are atomic absorption, which uses the attenuation of a beam of light of the appropriate wavelength by the atomized metal as the measure of concentration, and anodic stripping voltammetry, which is an electrochemical technique. Eurther details of all these procedures are available in standard texts ([20], and see also this chapter s Further Reading). 

For an idea of some historic and more recent applications of electrochemical techniques, the reader is referred to Table 2.11 of applications providing examples of applications of electrochemical analytical techniques to elemental determinations in a variety of materials. Shearer and Morris (1970) report on the microdetermination of fluorine in organic compounds with a fluoride ion electrode following an oxygen flask combustion based on the careful work of Morris. Dabeka et al. (1979) developed a microdiffusion and fluoride-specific electrode determination of fluoride in foods. Determination of lead and cadmium in foods by anodic stripping voltammetry ... 

The electroactive labels most used in genosensing design are ferrocene and its derivates [24-27] (the reversible oxidation process of ferrocene can be detected by means of several electrochemical techniques), osmium complexes [28], platinum complexes [29], gold complexes [30, 31], and metallic [32-36] or semiconductor nanoparticles [37]. Among the last ones, gold nanoparticles are the most used, their detection can be carried out by means of the measurement of resistance or capacitance changes, usually after an amplification procedure with silver, or by means of the anodic stripping voltammetry of Au(lll) obtained after the nanoparticle oxidation Fig. 9.3. 

In this context, anodic stripping voltammetry (ASV) is a very sensitive electrochemical technique mainly used for the analysis of trace concentrations of metallic species in solution, although detection of some organic species has also been carried out. Detection limits... 

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