Ferrocene-containing polyelectrolyte multilayer film-covered electrodes: electrocatalytic determination of ascorbic acid and use of inner blocking layers to improve the upper detection limit of the electrodes.
A multilayer film composed of ferrocene(Fc)-appended poly(allylamine hydrochloride) (Fc-PAH) and poly(potassium vinylsulfate) (PVS) has been prepared on the surface of a gold(Au) electrode by using a layer-by-layer self-assembly technique. Fc-containing polyelectrolyte multilayer (PEM) film-modified electrodes can electrochemically catalyze the oxidation of ascorbic acid successfully. For a 2 (Fc-PAH/PVS) bilayer-covered electrode the catalytic current increased linearly with increasing concentration of ascorbic acid over the concentration range 6 micromol L(-1)-3 mmol L(-1). To extend the dynamic range for ascorbic acid, the surface of the Au electrode was first covered with a (PAH/PVS)(2) film on which an additional (Fc-PAH/PVS)(5) film was coated. This strategy successfully extended the dynamic range of the electrode up to 25 mmol L(-1) ascorbic acid, because the (PAH/PVS)(2) layer blocked access of ascorbic acid to the electrode surface. The upper detection limit of the (PAH/PVS)(2) (Fc-PAH/PVS)(5) film-modified electrode is much higher than those of Fc-based ascorbic acid sensors reported so far. Electron transfer is diffusion-controlled within the (PAH/PVS)(2)(Fc-PAH/PVS)(5) film.
Liu
Aihua
A
Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
Anzai
Jun-Ichi
J
D001205:Ascorbic Acid / Q000032:analysis*; D002384:Catalysis; D004566:Electrodes; D005296:Ferrous Compounds / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D008567:Membranes, Artificial; D000075163:Metallocenes; D015394:Molecular Structure; D011073:Polyamines / Q000737:chemistry*; D011145:Polyvinyls / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013499:Surface Properties
D005296:Ferrous Compounds; D008567:Membranes, Artificial; D000075163:Metallocenes; D011073:Polyamines; D011145:Polyvinyls; C019050:polyvinyl sulfate; C063994:polyallylamine; D006046:Gold; D001205:Ascorbic Acid; C004998:ferrocene