Electrochemical methods - Analytical Electrochemistry in Textiles - page 65

¨

RO e + n

-

[2.60]

In the forward square-wave step, R is oxidised to O giving rise to a posi-
tive current; this assumes that the concentration of the reaction product O
in the vicinity of the electrode surface increases. During the reverse square-
wave step, this reaction product O is reduced back to its initial form, being
R. This results in a measured negative current. The difference I 1 - I 2 is a
higher signal than I 2 and I 1 individually, because it is the difference between
two signals that are opposite in sign. The resulting square-wave voltammo-
gram shows a differential shape with a peak maximum equal to the half-
wave potential and located at the same peak potential of the individual
signals from the oxidation and reduction reaction. Detection limits in
square-wave voltammetry are of the order of 1 ¥ 10 -10 mol l -1 .

2.6.4 Other methods

Other methods 67 have been proposed and studied, which will not be dis-
cussed here. In principle, a large variety of methods can be proposed
because of the huge possibilities for variation of the applied potential in a
DC mode, AC mode and/or with pulses. For a more detailed overview of
voltammetric methods, reference is made to literature 67 .

2.7 References

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(1992) 163.
5. Nernst W., Merriam E.S., Z. Phys. Chem. , 52 (1905) 235.
6. Ives D.J.G., Janz G.J., Reference Electrodes , Academic Press, New York, 1961.
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