Amperometric and voltammetric electroanalysis

The great possibilities of amperometric and voltammetric electroanalysis both in stationary solution and in continuous flow are evident from the previous sections. However, the choice of which technique and experimental protocol to use depends on various factors, such as  

In the case of trace quantities, or any determination close to detection limits, accuracy is much more important than precision, as the former is the primary consideration as to whether a given trace level is acceptable or not. Theoretical detection limits are often defined in the literature as three times the standard deviation of the measurements, but practical detection limits are usually higher and are determined by levels of contamination that can be introduced through reagent and sample manipulation. 

The use of pulse techniques for electroanalytical determinations has been much publicized, and is applicable to both solid electrodes and the HMDE/SMDE. The development in recent years of square wave voltammetry (SWV)39 widens the possibilities beause of its rapidity (Section 10.9) it is especially useful because the time necessary to do an experiment is only 2 s, which means that a SMDE drop in the dropping mode can also be used for micromolar determinations. Progress obtained with pulse techniques40,41 has meant that applications of a.c. voltammetry have been few, but there is no theoretical reason for this. The very low detection limits achieved in stripping voltammetry result not only from the pre-concentration step but also from the use of pulse waveforms in the determination step. 

Another important future direction is in the use of microelectrodes and microelectrode arrays. They are often easier to manipulate by the inexperienced, and instrumentation is simpler. They can be used in highly resistive dirty media where conventional electrodes may be unuseable and are able to probe localized concentrations. Composite electrodes42, of which carbon paste is an example, if conveniently prepared, can act as microelectrode assemblies. In a more general sense, lithographic and 

Finally, the possibilities of automation of amperometric and voltammetric electroanalysis should be stressed, as well as the use of solvents other than water43. Pulse techniques are semi-automated by nature the responses can be transmitted directly to a microcomputer for immediate analysis. Fast on-line analysis in flow systems with automated calibration is one of the great advantages, which will be much exploited in the future. 

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Wangfuengkanagul and Chailapakul [9] described the electroanalysis of ( -penicillamine at a boron-doped diamond thin film (BDD) electrode using cyclic voltammetry. The BDD electrode exhibited a well-resolved and irreversible oxidation voltammogram, and provided a linear dynamic range from 0.5 to 10 mM with a detection limit of 25 pM in voltammetric measurement. In addition, penicillamine has been studied by hydrodynamic voltammetry and flow injection analysis with amperometric detection using the BDD electrode. 

Hart J and Wring S 1994 Screen-printed voltammetric and amperometric sensors for decentralized testing Electroanalysis 6 617-24 Wang J 1991 Modified electrodes for electrochemical sensors Electroanalysis 3 255-9... 

Napier, A. and J.P. Hart (1996). Voltammetric and amperometric studies of selected thiols and dimethyldisulfide using a screen-printed carbon electrode modified with cobalt phthalocyanine Studies towards a gas sensor. Electroanalysis 8(11), 1006-1013. 

Brett, A.M.O., Matysik, F.-M. and Vieira, M.T. (1997) Thin-film gold electrodes produced by magnetron sputtering. Voltammetric characteristics and application in batch injection analysis with amperometric detection. Electroanalysis, 9, 209. 

Hart, J.P. and Wring, S.A. (1994) Screen-printed voltammetric and amperometric electrochemical sensors for decentralized testing. Electroanalysis, 6, 617. 

The actual challenges in environmental electroanalysis may be seen in (1) development of new voltammetric and amperometric methods using BDD electrodes and their validation so that they can be routinely used in environmental, biochemical, and other laboratories (2) search on reasonable ways for construction of BDD-based sensors and extension of their applications in environmental analysis and (3) construction of field-deployable analytical devices based on BDD sensors for on-site monitoring of enviromnental pollutants. 

Zavazalova J, Dejmkova H, Barek J et al (2013) Voltammetric and amperometric determination of mixtures of aminobiphenyls and aminonaphthalenes using borrai doped diamond electrode. Electroanalysis 25 253—262... 

Barek J, Fischer J, Wang J (2011) Voltammetric and amperometric detection of nitrated explosives (a review). In Kalcher K, MeteUca R, Svancara 1 et al (eds) Sensing in electroanalysis, vol 6. University Press Centre, Pardubice, pp 139-147... 

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