Fast scan cyclic voltammetry selectivity

Sinusoidal voltammetry (SV) is an EC detection technique that is very similar to fast-scan cyclic voltammetry, differing only in the use of a large-amplitude sine wave as the excitation waveform and analysis performed in the frequency domain. Selectivity is then improved by using not only the applied potential window but also the frequency spectrum generated [28]. Brazill s group has performed a comparison between both constant potential amperometry and sinusoidal voltammetry [98]. 

To improve chemical selectivity, a triangular input waveform can be used that separates compounds into resolvable peaks. This form—cyclic voltammetry—can be carried out with high temporal resolution using high scan rates to allow the waveform to be completed in a short time. In fast-scan cyclic voltammetry (also known as fast cyclic voltammetry), waveforms last around 10 ms, and measurements are typically made every 10-200 ms. 

Because of its small size, selectivity, time response, and sensitivity, the carbon fiber microelectrode coupled with fast-scan cyclic voltammetry currently represents the most ideal sensor for the measure of kinetics and mechanisms of DA neurotransmission. Release and uptake sites (neuron terminals) are depicted in Figure 3 along with a typical example of DA release and uptake data monitored with a carbon-fiber microelectrode using FSCV. These sites are generically described as a cartoon merely to give the reader an idea of the relative size of the electrode versus the neuron terminals (release and uptake sites). 

As it can provide some of the most basic electrochemical information related to the reactivity of the selected analyte (peak potential and peak current) most instruments that perform amperometry can also perform some of the most basic voltammetric techniques. These techniques determine the current as a function of the potential applied to the WE (in a conventional three-electrode cell) and can be performed with relatively simple instrumentation [105,106]. As different signals can be combined in the input ports of the instrument, multiple variations of the technique have been developed including cyclic voltammetry, linear sweep voltammetry, linear sweep stripping voltammetry, stripping voltammetry [107, 108], fast-scan cyclic voltammetry [109], square-wave voltammetry [110],and sinusoidal voltammetry [111]. 

The majority of measurements for electroanalysis with microelectrodes are recorded under steady-state conditions by using either chronoamperometry (CA), linear sweep voltammetry (LSV) or cyclic voltammetry (CV) [1,2, 9,10]. Moreover, to solve problems related to the selectivity between species with similar redox potentials, pulsed techniques such as differential pulse voltammetry (DPV) [1, 7, 43 5] and square-wave voltammetry (SWV) [1, 45-49] have been employed. The use of the latter technique also minimizes the influence of oxygen in aerated natural samples [47]. In order to enhance sensitivity in these measurements, fast-scan voltammetry (FSV) [50] or the accumulation of analytes onto an electrode surface has also been performed, in conjunction with stripping analysis (SA) [51]. 

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