Estimation of hydrogen peroxide in plant extracts using titanium(IV).

Methods for the estimation of hydrogen peroxide in acetone extracts using titanium(IV) are likely to overestimate hydrogen peroxide when applied to plant leaves. Pigments appear to co-precipitate with the titanium complex and cannot be removed by washing with solvents. Fluoride, which specifically removes the color of the titanium-peroxide complex, removes only some of the color from the reactions with plant extracts. This problem has been avoided by extracting tissues with trichloroacetic acid, and measuring peroxide against catalase-treated blanks by its reaction with the complex of titanium(IV) with 4-(2-pyridylazo) resorcinol. Levels of hydrogen peroxide in leaves of a variety of species were found to range from about 0.1 to 0.6 mumol X g-1.