Filmes de polianilina eletropolimerizados para uso como indicador colorimétrico para detecção da amônia

Abstract

In this work, a colorimetric indicator was developed for the detection of volatile ammonia for application in intelligent packages, which could inform the consumer about the freshness of the fish. ammonia is the most representative volatile base in the degradation process of fishes. Polyaniline (PANI) is a conductive polymer, well known for being easily doped by protonation. In this work, a colorimetric indicator was developed by electropolymerization of PANI. Two electrochemical techniques, cyclic voltammetry (VC) and chronopherometry (Crono) were used to determine the best technique for the development of the indicator. The evaluation of the color variation occurred as a consequence of the doping of the film and was performed with a color chart. The morphology of the PANI films was evaluated by scanning electron microscopy (SEM) and different morphologies were verified for the film grown by VC and by Crono. The detection limit of NH4OH was determined using different concentrations, from 0.00015 to 15 mol L-1, the limit was determined from the lowest concentration for the doping of PANI-ES film. The indicator developed by VC obtained a detection limit of 0.05 mol L-1 and that by Crono obtained a limit of detection of 0.015 mol L-1.