Polarography, advanced

The difficulties in conventional polarography as mentioned in Section 3.3.1.1, especially the interference due to the charging current, have led to a series of most interesting developments by means of which these problems can be solved in various ways and to different extents. The newer methods concerned can be divided into controlled-potential techniques and controlled-current techniques. A more striking and practical division is the distinction between advanced DC polarography and AC polarography. These divisions and their further classification are illustrated in Table 3.1. In treating the different classes we have not applied a net separation between their principles, theory and practice, because these aspects are far too interrelated within each class. 

A.C. Aten and G.J. Hoytink, Advances in Polarography, Pergamon Press, Oxford, 1961. 

International Congress on Advances in Polarography, Cambridge, England, 1959 , 1960, vol. 3, p. 1142 (Chem. Abstr., 1963, 58, 237f and refs, therein). 

Zuman, P. Some Techniques in Organic Polarography. In Advances in Analytical Chemistry and Instrumentation (C. N. Reilley, Ed.), Vol. 2, p. 219. New York Interscience-Wiley 1963. 

Mercury and solid s-p metal electrodes show stable electrochemical behavior in nonaqueous media, in particular in dipolar aprotic solvents. This knowledge was important for the advancement of electrochemical methodology, e.g., the special branch of polarography in nonaqueous systems has emerged. When performing electrochemical experiments in nonaqueous media, special attention should be paid to the reasonable choice of reversible reference electrodes. 

D. E. Smith, AC polarography and related techniques, in Electro-analytical Chemistry - A Series of Advances. Vol. 1, A. J. Bard, editor, Marcel Dekker, New York, 1966, pp. 1—156. 

In the more advanced kinetic measurements, which were carried out by using chronopotentiometry [118], chronocoulometry [124, 139], linear [146] and convolution [18, 147] potential sweep voltammetry, or phase-sensitive ac polarography [142, 143], the ohmic drop was either numerically subtracted [118], or compensated [124, 139, 142, 143, 146, 147] with the help of the positive feedback. The feedback adjustment was based either on the assumption that the separation of the current peaks measured by the slow potential sweep voltammetry should reach the value of (59/z)mV [124, 139, 146, 147], or on the value of the solution resistance obtained by an ac bridge technique [142, 143]. However, the former adjustment is not very sensitive, whereas the estimated accuracy of 10 Q [142] in the latter case may not be... 

L. Serak, Advances in Polarography, Proc. 2nd Intern. Congr. Cambridge 1959 (Pergamon Press, London, 1960) p. 1057. 

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