A carbon-paste electrode (CPE) is made from a mixture of conducting

graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on lar ...

powder and a pasting liquid. These

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials d ...

s are simple to make and offer an easily renewable surface for electron exchange. Carbon paste electrodes belong to a special group of heterogeneous

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...

electrodes. These electrodes are widely used mainly for voltammetric measurements; however, carbon paste-based sensors are also applicable in coulometry (both amperometry and potentiometry).

Advantages

In general, CPEs are popular because carbon pastes are easily obtainable at minimal costs and are especially suitable for preparing an electrode material modified with admixtures of other compounds thus giving the electrode certain pre-determined properties. Electrodes made in this way are highly selective sensors for both

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemist ...

and organic

electrochemistry Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outco ...

. Carbon paste, glassy carbon paste, glassy carbon etc. electrodes when modified are termed chemically modified electrodes. Chemically modified electrodes have been employed for the analysis of inorganic and organic species.

Disadvantages

The biggest disadvantage of CPEs, which limits their applicability in practical analysis, is that success in working with carbon paste-based electrodes depends on the experience of the user. While this is true for any type of solid electrodes, CPEs are rather an exceptional case. In contrast to commercially available solid electrodes for which basic

electrochemical Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outc ...

characteristics are comparable for almost all products from each manufacturer, each carbon paste unit is an individual, where the physical, chemical and electrochemical properties may differ from one preparation to another. For this reason each probe must be

calibrate In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known ...

d individually. While this may not be an issue in a research environment, it would be a considerable burden in production service.

References

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