Collect. Czech. Chem. Commun. 1995, 60, 65-75

Adsorption and Accumulation of Neutral Red at Mercury/Solution Interface

Mohamed S. Ibrahim, Zahra A. Ahmed, Moustafa M. Kamal and Yassein M. Temerk

Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt


The voltammetric behaviour of protonated and nonprotonated neutral red (NR) has been studied at a hanging mercury drop electrode (HMDE) by using alternating current (AC) and cyclic voltammetry (CV). The AC voltammetric behaviour and the morphology of the adsorption redox peaks indicate that interactions between adsorbed molecules are substantial and that the nature of these interactions changes from moderately repulsive below pH 4 to strongly attractive above pH 6. Controlled adsorptive accumulation of NR on the HMDE provides the basis for the direct stripping measurement of that compound in the nanomolar concentration level. Adsorptive phase selective AC stripping voltammetry has been proved to be advantageous over any other assay technique, allowing a detection limit of 1.0 . 10-9 M NR to be reached.