Carmen Teijeiro

Diffusion coefficients of ammonium salts in aqueous solutions are theoretically estimated from the Onsager-Fuoss model. The influence of the ion size parameter a (mean distance of closest approach of ions), as well as of both the thermodynamic and the mobility factors on the variation of diffusion coefficients with concentration, is discussed. The aim of this chapter is to contribute to a better knowledge of the structure of these systems.

Stripping voltammetry (SV) is used to quantitatively determine concentrations of the anti-neoplastic drug mitomycin C (MMC) alone and in mixtures with 5-fluorouracil and cisplatin, both of which are used in combined chemotherapy with MMC. If the accumulation is performed at the potentials of MMC reduction (-0.35 V vs. SCE), reduced MMC is strongly adsorbed at the electrode. It is possible to prepare a MMC-modified electrode, which, after a washing step, is transferred to the background electrolyte to determine MMC by voltammetry. This procedure, which is termed transfer stripping voltammetry (TSV), helps to eliminate interferences and can be applied for a direct determination of MMC alone or in mixtures with other drugs in urine.