Desenvolvimento de métodos eletroquímicos de análise empregando papel pirolisado como eletrodo de trabalho

Abstract

The possibility of using pyrolyzed paper as disposable working electrode for the determination of trace metals and hydrogen peroxide is reported for the first time. A small piece of pyrolyzed paper (0.7 x 0.7 cm) was positioned on the underside of the electrochemical cell using a rubber O-ring, which defined the area of the electrode. A large number of electrodes can be obtained from a single piece of standard dimensions (2.5 cm x 7.5 cm) of paper, which minimizes the cost per unit. The electrochemical performance of the pyrolyzed paper was demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy and the determination of Zn, Cd and Pb by square-wave anodic stripping voltammetry and hydrogen peroxide by amperometry with electrodes modified with graphene and Prussian blue derivatives. In the determination of metals, the unmodified pyrolyzed paper showed excellent performance for the detection of Pb and Cd (LD = 0.19 and 0.16 p,g L-1, respectively). In the presence of Bi3+ (in-situ film formation), simultaneous determination of Zn, Cd and Pb (LD = 0.26, 0.25 and 0.39 p,g L-1, respectively) was possible. In the second work, the determination of hydrogen peroxide showed good results using pyrolyzed paper electrodes modified with reduced graphene oxide with Prussian blue (rGO / AP) and graphene oxide with Prussian blue (GO / AP) (LD = 0.18 and 0.43 x 10-6 mol L-1, respectively).