Voltammetric techniques stripping

Stripping Voltammetry One of the most important quantitative voltammetric techniques is stripping voltammetry, which is composed of three related techniques anodic, cathodic, and adsorptive stripping voltammetry. Since anodic strip-... 

The properties of anodic layers of HgS formed on mercury in sulfide solutions have been investigated in comparison with anodic sulfide layers of cadmium and bismuth. Also, the electrochemistry of mercury electrodes in aqueous selenite solutions has been studied (see Sect. 3.2.1). The problem with the presence of several cathodic stripping peaks for HgSe in acidic Se(IV) solutions has been addressed using various voltammetric techniques at a hanging-mercury-drop electrode [119]. 

The Model 384B (see Fig. 5.10) offers nine voltammetric techniques square-wave voltammetry, differential-pulse polarography (DPP), normal-pulse polar-ography (NPP), sampled DC polarography, square-wave stripping voltammetry, differential pulse stripping, DC stripping, linear sweep voltammetry (LSV) and cyclic staircase voltammetry. 

Donat and Bruland [217] determined low levels of nickel and cobalt in seawater by a voltammetric technique, and the nioxime complexes of the two elements were concentrated on a hanging mercury drop electrode. The current resulting from the reduction of Co (II) and Ni (II) was measured by differential pulse cathodic stripping voltammetry. Detection limits are 6 pM (cobalt) and 0.45 nM (nickel). 

Explain what is done in anodic stripping voltammetry. Why is stripping the most sensitive voltammetric technique What are its limitations ... 

If a stationary electrode is used, such as platinum, gold, or glassy carbon, the technique is called voltammetry. One useful voltammetric technique is called stripping voltammetry, in which the product of a reduction is deposited on the surface on purpose and then stripped off by an oxidizing potential— a potential at which the oxidation of the previously deposited material occurs. This technique can also use a mercury electrode, but one that is held stationary. 

Polarography has been largely replaced by voltammetry with electrode materials that do not present the toxicity hazard of mercury. Principles described for the mercury electrode apply to other electrodes. Mercury is still the electrode of choice for stripping analysis, which is the most sensitive voltammetric technique. For cleaning up mercury spills, see note 18. 

Stripping is the most sensitive voltammetric technique (Table 17-2), because analyte is concentrated from a dilute solution. The longer the period of concentration, the more sensitive is the analysis. Only a fraction of analyte from the solution is deposited, so deposition must be done for a reproducible time (such as 5 min) with reproducible stirring. 

Recent studies describe the use of cyclic voltammetry in conjunction with controlled-potential coulometry to study the oxidative reaction mechanisms of benzofuran derivatives [115] and bamipine hydrochloride [116]. The use of fast-scan cyclic voltammetry and linear sweep voltammetry to study the reduction kinetic and thermodynamic parameters of cefazolin and cefmetazole has also been described [117]. Determinations of vitamins have been studied with voltammetric techniques, such as differential pulse voltammetry for vitamin D3 with a rotating glassy carbon electrode [118,119], and cyclic voltammetry and square-wave adsorptive stripping voltammetry for vitamin K3 (menadione) [120]. 

On one hand, mercury-film electrodes give increased resolution when compared to the hanging mercury drop electrode (HMDE). On the other hand, BCFMEs have the inherent characteristics of an ERD. Hence, it would be extremely desirable to combine all properties. Furthermore, this combination may provide additional advantages such as easy handling, low cost, and other well-known analytical advantages associated with the use of UMEs itself, for example, the elimination of convective hydrodynamics along the accumulation step in stripping voltammetric techniques. 

Voltammetric techniques have also been employed for on-chip EC detection. For instance, anodic stripping voltammetry (ASV) was used to detect Pb in a Si-Pyrex chip [770] or a polyimide chip [229]. 

Mocak, J. Bond, A.M. Mitchell, S. Scollary, G. 17. A statistical overview of standard (lUPAC and ACS) and new procedures for determining the limits of detection and quantification Applied to voltammetric and stripping 18. techniques. Pure Appl. Chem. 1997, 69, 297-328. 

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). 

Because of its remarkable sensitivity (down to 10-11 M) stripping analysis is the most widely used voltammetric technique for trace metal determination in clinical samples (Wang, 1982A). Stripping analysis can be considered as a two-step technique. In the first step, metals in solution are effectively preconcentrated onto the working electrode by electrodeposition ... 

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