Voltammetry amperometry

Immunoassays, electrochemical — A quantitative or qualitative assay based on the highly selective antibody-antigen binding and electrochemical detection. Poten-tiometric, capacitive, and voltammetric methods are used to detect the immunoreaction, either directly without a label or indirectly with a label compound. The majority of electrochemical immunoassays are based on -> voltammetry (-> amperometry) and detection of redox-active or enzyme labels of one of the immunochemical reaction partners. The assay formats are competitive and noncompetitive (see also -> ELISA). 

ROMANI A, MINUNNI M, MULINACCI N, PINELLI P and VINCIERI E F (2000), Comparison among differential pulse voltammetry, amperometrie biosensor, and HPLC/DAD analysis for polyphenol determination , J... 

Electrochemical Potentiometry Conductimetry Voltammetry Amperometry Coulometry ... 

One of the two main electroanalytical techniques involved in in vivo measurements is voltammetry (amperometry), which gives information concerning the concentration of the electrochemically active substances generated or translocated in living cells or tissues. The data obtained from both techniques give not only static but also dynamic information. 

This section describes the deposition and characterization of a Hg hemisphere on Pt UMEs (3). Two methods of fabricating hemispherical Hg/Pt UMEs are described electrodeposition from an inorganic mercnry solution or from controlled contact of the Pt UME with a mercury drop. Electrochemical characterization can be performed using linear sweep voltammetry, amperometry (see Chapter 11) and SECM feedback experiments (see Chapter 12). 

Electrolysis is the basis of the analytical techniques of polarography, voltammetry, amperometry and coulometry (see Topic C9). Electrolysis may also be used for the deposition, production and purification of materials. For example. 

There are basic electroanalytical characterization techniques that are consistently used to evaluate performance characteristics of BFCs. Standard electroanalytical techniques include linear sweep voltammetry, cyclic voltammetry, amperometry, and both galvanostatic and potentiostatic coulometry [1-5]. 

The largest division of interfacial electrochemical methods is the group of dynamic methods, in which current flows and concentrations change as the result of a redox reaction. Dynamic methods are further subdivided by whether we choose to control the current or the potential. In controlled-current coulometry, which is covered in Section IIC, we completely oxidize or reduce the analyte by passing a fixed current through the analytical solution. Controlled-potential methods are subdivided further into controlled-potential coulometry and amperometry, in which a constant potential is applied during the analysis, and voltammetry, in which the potential is systematically varied. Controlled-potential coulometry is discussed in Section IIC, and amperometry and voltammetry are discussed in Section IID. 

In potentiometry, the potential of an electrochemical cell under static conditions is used to determine an analyte s concentration. As seen in the preceding section, potentiometry is an important and frequently used quantitative method of analysis. Dynamic electrochemical methods, such as coulometry, voltammetry, and amper-ometry, in which current passes through the electrochemical cell, also are important analytical techniques. In this section we consider coulometric methods of analysis. Voltammetry and amperometry are covered in Section 1 ID. 

Electrochemical Detectors Another common group of HPLC detectors are those based on electrochemical measurements such as amperometry, voltammetry, coulometry, and conductivity. Figure 12.29b, for example, shows an amperometric flow cell. Effluent from the column passes over the working electrode, which is held at a potential favorable for oxidizing or reducing the analytes. The potential is held constant relative to a downstream reference electrode, and the current flowing between the working and auxiliary electrodes is measured. Detection limits for amperometric electrochemical detection are 10 pg-1 ng of injected analyte. 

LCEC is a special case of hydrodynamic chronoamperometry (measuring current as a function of time at a fixed electrode potential in a flowing or stirred solution). In order to fully understand the operation of electrochemical detectors, it is necessary to also appreciate hydrodynamic voltammetry. Hydrodynamic voltammetry, from which amperometry is derived, is a steady-state technique in which the electrode potential is scanned while the solution is stirred and the current is plotted as a function of the potential. Idealized hydrodynamic voltammograms (HDVs) for the case of electrolyte solution (mobile phase) alone and with an oxidizable species added are shown in Fig. 9. The HDV of a compound begins at a potential where the compound is not electroactive and therefore no faradaic current occurs, goes through a region... 

Monitoring enzyme catalyzed reactions by voltammetry and amperometry is an extremely active area of bioelectrochemical interest. Whereas liquid chromatography provides selectivity, the use of enzymes to generate electroactive products provides specificity to electroanalytical techniques. In essence, enzymes are used as a derivatiz-ing agent to convert a nonelectroactive species into an electroactive species. Alternatively, electrochemistry has been used as a sensitive method to follow enzymatic reactions and to determine enzyme activity. Enzyme-linked immunoassays with electrochemical detection have been reported to provide even greater specificity and sensitivity than other enzyme linked electrochemical techniques. 

Membranes. Apart from the role of membranes180 in ISEs, there are at least three important applications of membranes as measurement aids in flow analysis. viz., as diffusion membranes in (1) (partial) dialysis and in (2a) membrane amperometry (MEAM) and (2b) membrane voltammetry (MEVA), and as Donnan membranes in (3) differential ionic chromatography. 

Ampere, Andr6 current, electricity current amp (unit of current) amperometry amperometric voltammetry... 

Does potentiometry utilize galvanic cells or electrolytic cells Do voltammetry and amperometry utilize galvanic cells or electrolytic cells ... 

Voltammetry is the term given to electrochemical techniques which monitor the relationship between the voltage applied to an electrode system and the current that flows as a result of the reaction. It covers a wide range of different electrode techniques, many of which are specifically designed to monitor a particular chemical reaction. Voltammetry is generally divided into two main subdivisions of polarography and amperometry. 

An amperometric technique relies on the current passing through a polarizable electrode. The magnitude of the current is in direct proportion to the concentration of the electroanalyte, with the most common amperometric techniques being polarography and voltammetry. The apparatus needed for amperometric measurement tends to be more expensive than those used for potentiometric measurements alone. It should also be noted that amperometric measurements can be overly sensitive to impurities such as gaseous oxygen dissolved in the solution, and to capacitance effects at the electrode. Nevertheless, amperometry is a much more versatile tool than potentiometry. 

Amperometry The techniques and methodology of determining a concentration as a function of current the most popular amperometric measurement technique is voltammetry. 

Polarography and Voltammetry (DC, AC, SW, pulse methods for each) Amperometry Chronopotentiometry, Polarography and Voltammetry at the interface between two immiscible electrolyte solutions (ITIES)... 

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