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In this study, a glassy carbon electrode (GC) was modified with an electropolymerized film of 1-naphthylamine (1-NAP) with a subsequent overoxidation treatment in 0.2 M sodium hydroxide solution. This polymer p-1-NAPox film coated GC electrode was used for the selective determination of dopamine (DA) in the presence of a triple concentration of ascorbic acid (AA).These studies were performed using cyclic voltammetry and square-wave voltammetry at physiological pH. p-1-NAPox shows an attractive permselectivity, a marked enhancement of the current response and antifouling properties when compared to a bare GC electrode activated in basic media. With a preconcentration time of 3 minutes at open circuit, linear calibration plots were obtained for DA in buffer solution (pH 7.4) over the concentration range from 1 Â 10 À6 -1 Â 10 À4 M with a detection limit of 1.59 Â 10 À7 M.

Eletrodos modificados com filmes de poli-bendizina são quimicamente estáveis no intervalo de pH en tre 0 e 7 e podem ser ciclados de -0.200 a 0.850 V sem evidência de decomposição. Conseqüentemente, neste intervalo de potencial, eles podem ser usados como ma te rial eletródico para a oxidação ou redução de diferentes espécies. Uma propriedade interessante deste eletrodo modificado é sua capacidade de capturar e quantificar o íon Ag(I) presente na solução. Para obter resultados reproduzíveis a etapa de acumulação foi realizada numa solução de AgNO 3 com um tampão de acetato de pH = 7. Após redução para Ag(0) na mesma solução, a etapa de determinação foi executado por voltametria cíclica. A resposta analítica corresponde à oxidação para Ag(I) e a quantia de prata incorporada ao filme foi determinada a partir da carga do pico anódico. O uso potencial deste método para a determinação analítica da prata é discutido.Elec trodes mod i fied with poly-benzidine films are chem i cally sta ble in the pH range between 0 and 7, and can be cy cled from -0.200 to 0.850 V with no ev i dence of de com po si tion. Con se quently, in this po ten tial range, they can be used as elec trode ma te rial for ox i da ti on or reduc tion of dif fer ent spe cies. One in ter est ing prop erty of this mod i fied elec trode is its ca pac ity to cap ture and quan tify Ag(I) ion pres ent in so lu tion. To ob tain re pro duc ible re sults, th e ac cumu la tion step was car ried out in a AgNO 3 so lu tion with ac e tate buffer at pH = 7. Af ter re duc tion to Ag(0) in the same so lu tion, the de ter mi na tion step was per formed by cy clic voltammetry. The an a lyt i cal re sponse cor re sponds to sil ver ox i da tion to Ag(I), and the amount of sil ver incor po rated into the film was de ter mined from the charge of the an odic peak. The po ten tial us e of this method for an a lyt i cal de ter mi na tion of sil ver is dis cussed. Key words: mod i fied elec trodes, poly-benzidine, electroanalysis, sil ver(I) In tro duc tionIn the con text of metal ion anal y ses, chem i cally mod ified elec trodes (CMEs) pos sess ing prop er ties have emerged as one of the most at trac tive ar eas for re search 1-4 . Among their ad van tages are their in her ent high se lec tiv ity and sen si tiv ity. Methods that have been used for elec trode mod i fi ca tion in clude phys i cal coat ing, co va lent at tach ment and electropolymerization. Par tic u larly, electropolymerization of fers an ef fec tive and ver sa tile way to de posit poly mer film on a sub strate elec trode [5][6][7][8] .The electrooxidation of ar o matic amines is well known, and dif fer ent as pects of their mech a nism have been elu cidated 9,10 . Pre vi ous stud ies show that when ar o matic amines such as naphtidine 5 , 1-naphtylamine 6 , and benzidine (Bz) 7 are electrooxidized, they fol low a com plex re ac tion to give a poly mer that ad heres to the elec trode sur face. These polymers which ad here to a base metal are con duc tors, and their dop ing grade can be con trolled 9,11,12 .Re c...

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