Characterization and electroanalytical application of ω-mercaptoalkanesulfonic acid monolayers on gold

Self-assembled monolayers (SAMs) of ω-mercaptoalkanesulfonic acid on gold surfaces have been studied by electrochemistry and other surface techniques. In spite of the fact that these monolayers are disorganized, i.e., of "brush" type, they are impermeable to inorganic anions due to their high negative charge. Moreover, we find that an ω-mercaptodecanesulfonic acid (MDS) monolayer is also impermeable to organic species, regardless of their charge, because of its high hydrophilicity. The combination of these properties made it possible to apply gold electrodes modified with MDS for the determination of iron(III) ions in the presence of organic species that are either electroactive throughout the same potential window or form strong complexes with iron(III).