The aim of this work was to develop an electrochemical cell and a methodology based on an amperometric determination of hydrogen peroxide in whitening gel samples under a boron-doped diamond electrode using flow injection analysis. Different parameters were evaluated to obtain the best conditions of analysis: among them, the flow of electrolyte at 2.8 mL min-1, the loop sampling 175 μL (28.5 cm), an analytical length of 159 μL (25 cm) and an applied potential of +0.60 V vs. Ag/AgCl(sat). The proposed method was suitable in terms of precision of results (RSD <10%); the accuracy was confirmed in the analysis of the gels through addition and recovery studies with results between 74 and 107%. The method was then applied to the analysis of tooth-whitening gel samples, acquired in different cities of the region. Regarding the results, a medium concentration value of 2.39% (w/w) was observed.
Keywords: Whitening gel; amperometry; boron-doped diamond electrode; hydrogen peroxide.