Self-assembled monolayer gold electrode for surfactant analysis

Studies on adsorption of cetyltrimethylammonium bromide at carbon paste electrode and the enhancement effect in thyroxine reduction by voltammetry and electrochemical impedance spectroscopy

“…The linear dependence of the oxidation peak current on the square root of the scan rate showed that K 4 Fe(CN) 6 underwent a diffusion-controlled process. It has been previously established that CTAB could form a special ion complex with K 4 Fe(CN) 6 through electrostatic interaction [19] and might be adsorbed at the interface between the hydrophobic surface and the aqueous solution [20]. The proposed behavior of K 4 Fe(CN) 6 at a carbon paste electrode in the presence of CTAB might arise from the adsorption of CTAB at the electrode surface and the interaction between CTAB and K 4 Fe(CN) 6 , i.e., the electrochemical response of K 4 Fe(CN) 6 in the presence of CTAB could be utilized to investigate the adsorptive behavior of CTAB at a carbon paste electrode, which might be able to explain the enhancement effects of surfactants in some electroanalytical systems.…”

“…The onset of the iodine reduction on oxidized T 4 above 1.0 Â 10 À5 M CTAB can be well explained with the variation of the adsorption/desorption rate of CTAB with CTAB concentration. At low concentrations, the adsorption/desorption rate of CTAB is fast [19]. Thus, the oxidized T 4 that is combined with adsorbed CTAB might be desorbed from the electrode surface with CTAB desorption before its reduction.…”

“…This might arise from the different coordination patterns between K 4 Fe(CN) 6 and T 4 with CTAB. According to Gerlache et al [19], the stoichiometry determined by potentiometric titration for the ion complexes of K 4 Fe(CN) 6 and CTAB ([Fe(CN) 4À 6 /CTA þ ]) was 1:4, i.e., one molecule of K 4 Fe(CN) 6 combines with four molecules of CTAB. Thus, the desorption of one or two molecules of CTAB could not effectively influence the voltammetric responses of adsorbed K 4 Fe(CN) 6 .…”

Self‐Assembled Monolayers on Electrodes

“…182,183 Cationic surfactants are quantified by the current obtained for the reduction of ferricyanide at an octadecanethiol-coated electrode; adsorption of the cationic surfactant on the SAM enhances the concentration of ferricyanide and hence the current. 184 Designed binding sites in the SAM can greatly enhance the selectivity of the electrode (Table 2). Cyclodextrins, either with a pendant thiol or attached to an existing SAM, bind electroactive analytes like ferrocene 185 or quinone.…”

Emprego de monocamadas auto-organizadas no desenvolvimento de sensores eletroquímicos

“…Um emparelhamento perfeito entre os alcanotióis (geralmente com uma inclinação de 20 a 30 graus em relação à normal da superfície) e o retículo do ouro resulta numa estrutura altamente ordenada (Figura 2) e tem feito deste sistema objeto de um grande número de estudos por meios espectroscópicos, microscópicos e eletroquímicos 12 . Vári-os trabalhos têm sido dedicados ao entendimento da estrutura e do ordenamento das monocamadas, que são caracterizadas pelo alto grau de organização e têm sido empregadas em estudos de transferência de elétrons [34][35][36][37][38][39] , adsorção de proteínas 38,[40][41][42][43] e, principalmente, em vários campos da eletroanalítica 12,[19][20][21][22][44][45][46][47][48][49][50][51][52][53] . A preparação da monocamada possui um papel fundamental no desempenho eletroanalítico do eletrodo modificado.…”