Desenvolvimento de sensor potenciométrico baseado em eletrodos de carbono grafite para determinação de ácido cítrico em bebidas

Abstract

In this work, a potentiometric sensor based graphite carbon electrodes was constructed. The proposed sensor was applied for determination of citric acid in beverages using a flow system. The maximum response was obtained for 1.0 mL min-1 flow rate of the carrier stream (0.1mol L-1 KCl at pH 7.0) and 65 μL of citric acid. This electrode has a wide linear dynamic range between 0.07 - 7.0 mmol L-1 , quantification limit and detection limit of 15,60 nmol L-1and 5,15 nmol L-1, respectively. The proposed sensor displayed good selectivities over a variety for other anions (carboxylates and organic acids).The electrode is easily constructed at a relatively low cost with fast response time (within 120 s) without significant change in its performance characteristic. The potentiometric sensor was successfully applied to the determination of citric acid in real food samples, that is, juices and isotonic drinks.