The formation of an inclusion complex between 4-aminobiphenyl (4-AB) and b-cyclodextrin molecules (b-CD), allows the use of thiolated b-CDs as chemi-adsorbed material on a Au electrode as a self-assembled submonolayer for the selective square wave voltammetric determination of 4-AB. The submonolayer was characterized by reductive desorption and an association constant of 1.2 10 4 L/mol was obtained. The optimization of variables yielded a linear dependence of ip/4-AB concentration in the range of 10 À5 to 10 À4 mol/L. The selectivity of the method was evaluated in the presence of other aromatic amines obtaining better results with the modified electrode. This methodology was applied to the voltammetric determination of 4-AB in wastewater samples.

Alkanethiols, such as di-n-octadecyldisulfide, octanethiol, and ethanethiol, have been employed for self-assembled monolayers on a gold electrode to study the influence of their chain length on the electrochemical response of aniline and 4-aminobiphenyl. The responses of individual solutions and mixtures of both compounds show that the organization of the submonolayer built can improve the selectivity in the electrochemical analysis of those aromatic amines. The use of C8 10 À2 M allows the analysis of 4-aminobiphenyl avoiding the aniline response. A better resolution for the analysis of those amine mixtures was obtained if a C18 10 À6 M modified gold electrode was used instead of an unmodified one.