Stripping voltammetry SV

Two very sensitive methods, called anodic and cathodic stripping voltammetry (SV), are used to measure trace of metal. They are carried out in two stages  

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The method of stripping voltammetry (SV) is one of the most perspective methods in concentration range of thallium(I) determination of 10 -10 M. Achievement of high sensitivity of thallium(I) determination needs carrying out its additional concentration and sepai ation from other metals which ai e close by electrochemical properties. For these purposes it is offered to use a method of coprecipitation with collector. The combination of SV and a method of coprecipitation on a collector have shown that minimum detectable concentration can be decreased by 2-3 orders of magnitude. 

Stripping voltammetry or stripping analysis has a special place in electrochemistry because of its extensive application in trace metal analysis. Stripping voltammetry (SV) is a two-step process as shown schematically in Fig. 18b. 12. In the first step, the metal ion is reduced to metal on a mercury electrode (thin mercury film on glassy carbon or a HMDE) as amalgam. 

Stripping voltammetry (SV) comprises one of the major families of electroanalytical chemistry. The strength of SV is in its extremely low detection limits... 

The first stage in stripping electroanalytical methods is the accumulation of the electroactive substance either on the surface or in the bulk of a liquid electrode (mercury electrodes). The second stage consists of electrode polarization, obtaining cathodic or anodic voltam-mograms (stripping voltammetry (SV)) that give information on the nature and concentration of electroactive analytes [7]. 

Potentiometric measurements by ion-selective electrode potentiometry (ISE) or ion-selective field effect transistors (ISFET), stripping voltammetry (SV) and stripping chronopotentiometry (SCP) are analytical techniques capable of giving not only the total concentration of analytes in water samples, but also metal speciation information, since they are sensitive to the free metal fractiOTi. This capability is especially useful for the study of metal distribution and transfer among environmental compartments in water, as previously commented in this subchapter (Fig. 3.1). It s important to stress that SV and SCP are dynamic techniques, whereas ISE and ISFET are equilibrium techniques. For more details on potentiometric measurements, see Chap. 9 vol 2. 

In the stripping voltammetry, in general it is anodic SV which, owing to its extreme sensitivity and selectivity together with its cheapness, has gained so much analytical importance that for instance the Kemforschungsanlage Jiilich (F.R.G.) recently (1983) replaced their atomic absorption spectrometer with an SV system for the simultaneous determination of Cu, Cd, Pb, etc. 

Anodic (or cathodic) stripping voltammetric (SV) techniques can be used to measure traces of metal in the environment. These methods are very sensitive and their precision is in the order of l to 2%. Stripping voltammetry is carried out in two stages. 

Anatoliy Aleksandrovich Kaplin (October 20, 1937-July 27, 1989) (Fig. 5.4.3.4) has developed SV for the determination of traces in semiconductor and other high-purity materials [51]. He was an excellent organizer, not only of research work (he has supervised 20 PhD theses) but also of conferences, e.g., of four All-Union Conferences on Stripping Voltammetry in Tomsk (1973,1982,1986,1990) under the chairmanship of Stromberg. Parallel to Ye. Ya. Neyman who worked in Moscow, Kaplin started to study the formation of complex amalgams, intermetaUic compounds in mercury, and solid solutions under the conditions of SV. Anodic currents of such systems were described by Kaplin on the basis of regular solution thermodynamics. Kaplin defended his doctoral thesis entitled Inverse voltammetric analysis of microsamples, crystal layers and films before a conunission in Moscow. 

Figure 6 shows a scheme of the sequential injection anodic stripping voltammetry system (SI-ASV) used for inorganic arsenic speciation in water samples. The system consisted of a MicroBu 2030 multisyringe burette with programmable speed (CS, Crison, Spain) used to aspire and dispense the reagent solutions, an eight-way selection valve (SV, Crison), a home-made tubular electrochemical cell (D), and a mixer chamber (MC). 

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