ISSN 1061-9348, Journal of Analytical Chemistry, 2012, Vol. 67, No. 11, pp. 869–879. © Pleiades Publishing, Ltd., 2012. Original Russian Text © G.K. Ziyatdinova, E.R. Ziganshina, H.C. Budnikov, 2012, published in Zhurnal Analiticheskoi Khimii, 2012, Vol. 67, No. 11, pp. 968–979. 869 Surfactants are able to manifest themselves in polarograms of test solutions, which is usually related to changes in the properties of the double electric layer. Even at the dawn of the development of polarog- raphy and voltammetry, neutral organic surfactants were used for the suppression of polarographic max- ima. Aliphatic alcohols with six to eight carbon atoms appeared as capacitive peaks in voltammograms at mercury electrodes; this made it possible to use them for developing determination methods based on the so-called depression of differential capacitance. These studies have been reviewed in many books on electro- chemistry and voltammetry, for example [1]. The effects of surfactant adsorption appeared not only on the suppression of polarographic maxima but also on the inhibition of the electrochemical steps of the process to cause a shift of wave or peak potentials in voltammograms to higher values or splitting of a multi-electron wave into several steps. The analytical applications of these adsorption effects were of limited utility. In particular, they were used for determining the residual amounts of surfactants in aqueous test samples. Currently, studies of this kind are mainly of historical interest. However, the adsorption effects of analyte species are widely used in order to increase the sensitivity of their determination. The variety of currently available surfactants and hence their properties makes it possible to use this group of compounds for controlling analytical signals in voltammetry and, consequently, to increase the sen- sitivity and selectivity of amperometric response to a particular analyte. It is well known that amphiphilic organic mole- cules can occur in various forms in aqueous solutions; this fact long ago came to the attention of chemists. These forms are related to the properties of surfactants containing negatively (–S –S –СOO – ) or posi- tively charged groups or a polar oxyeth- ylene chain (–OC 2 H 4 ) n and a long nonpolar hydrocar- bon radical having from 8 to 18 carbon atoms. In water, surfactant molecules primarily occupy its sur- face to form a monomolecular layer, and the aggre- gates of surfactant molecules (micelles) are spontane- ously formed upon reaching a critical micelle concen- tration (CMC). Because of this, the solutions of surfactants can be classified as self-organizing systems [2, 3]. All surfactants are divided into the three classes: anionic, cationic, and nonionic surfactants. Anionic surfactants: sodium dodecylsulfate (SDS) and sodium dodecylbenzenesulfonate. Cationic surfactants: N-dodecylpyridinium bro- mide, cetylpyridinium bromide (CPB), and cetyltrim- ethylammonium bromide (CTAB). Nonionic surfactants: Brij  35, Triton X-100, and Tween 20. The physicochemical properties and processes in the solutions of surfactants were considered in detail earlier [4, 5]. Surfactants are in active current use in spectro- scopic techniques [6], titrimetry, various versions of chromatography [7], extraction, capillary and gel electrophoresis, and other methods for the separation and determination of organic and inorganic sub- stances. These problems were considered in detail by Shtykov [8]. In the past decades, surfactants have been used in electroanalytical techniques [9–12]. Application of surfactant-containing media to the voltammetry of biologically active compounds. Aque- ous micellar solutions and microemulsions, in partic- O 3 , - O 4 , - N CH 3 ( ) 3 + – ( ) Application of Surfactants in Voltammetric Analysis G. K. Ziyatdinova, E. R. Ziganshina, and H. C. Budnikov A.M. Butlerov Institute of Chemistry, Kazan (Volga Region) Federal University, ul. Kremlevskaya 18, Kazan, 420008 Tatarstan, Russia Received November 8, 2011; in final form, February 3, 2012 Abstract—The possibilities of applying surfactants to the voltammetry of various biologically active com- pounds are generalized. Attention is focused on micellar solutions and surfactant-modified electrodes in the determination of a number of organic compounds, including antioxidants. It is demonstrated that the use of surfactants makes it possible to improve analytical characteristics and, in some cases, to simultaneously deter- mine different analytes. Keywords: surfactants, electrochemical methods, modified electrodes, biologically active compounds, phar- maceutical preparations DOI: 10.1134/S106193481211010X REVIEWS