Analysis by electrochemical methods

In CSV the element is pre-concentrated on the electrode in an oxidized form, either by adsorption as a surface-active complex or precipitation as an insoluble oxide or salt. The adsorption method has led to the successful development of procedures to detect some 20 elements (metals as well as metalloids) in seawater. The principle of this method will be set out in detail in this chapter, along with details of the determination of a few elements as examples. 

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Table 8.76 shows the main characteristics of voltammetry. Trace-element analysis by electrochemical methods is attractive due to the low limits of detection that can be achieved at relatively low cost. The advantage of using standard addition as a means of calibration and quantification is that matrix effects in the sample are taken into consideration. Analytical responses in voltammetry sometimes lack the predictability of techniques such as optical spectrometry, mostly because interactions at electrode/solution interfaces can be extremely complex. The role of the electrolyte and additional solutions in voltammetry are crucial. Many determinations are pH dependent, and the electrolyte can increase both the conductivity and selectivity of the solution. Voltammetry offers some advantages over atomic absorption. It allows the determination of an element under different oxidation states (e.g. Fe2+/Fe3+). 

Frenzel W, Bratter P (1987) Applications of electroanalytical flow analysis in the trace element determination of biological materials. In Bratter P, Schramel P (eds) Trace element analytical chemistry in medicine and biology. Walter de Gruyter, Berlin, p 337 van den Berg CMG (1999) Determination of trace elements. Analysis by electrochemical methods. In Grasshoff K, Kremling K, Ehrhardt M (eds) Methods of seawater analysis. Wiley-VCH, Weinheim, p 302 Kalvoda R (2000) Crit Rev Anal Chem 30 31 Mart L (1979) Fresenius Z Anal Chem 296 350 Barek J, Mejstfik V, Muck A, Zima J (2000) Crit Rev Anal Chem 30 37... 

Analysis by electrochemical methods 305 Table 12-5. Electrochemical determination of other elements in seawater. 

Instrumental Aspects of Food Analysis by Electrochemical Methods... 

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