Amperometric titration of phenolic compounds using crude extract of sweet potato (Ipomoea batatas (L.) Lam.) as enzymatic source of polyphenol oxidase and titrant is proposed for determining phenols in wastewaters. This enzyme catalyses the oxidation of monophenol and diphenols by molecular oxygen producing o-quinone. The oxygen electrode was used as indicator electrode and the consumption of O2 in the solution was proportionally to the substrate concentration. This method provides a linear response for catechol, pyrogallol, hydroquinone, phenol and p-cresol in the concentration range of 2,0x10-5 a 4,0x10-4 mol L-1 and the recovery of catechol from two samples ranged from 97.7 to 102%. The results obtained for phenolic compounds in industrial wastewaters using the proposed procedure and those obtained using a standard method are in agreement at the 95 % confidence level.
polyphenol oxidase; enzyme; phenolic compound; wastewater
