Determination of catalase-like activity in plants based on the amperometric monitoring of hydrogen peroxide consumption using a carbon paste electrode modied with ruthenium(IV) oxide

• Published in: Phytochemical analysis Vol. 17; no. 4; pp. 255 - 261
• Main Authors: Dousikou, M.F, Koupparis, M.A, Efstathiou, C.E
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-07-2006
• Subjects: Amperometric determination; catalase; catalase-like activity; chemical analysis; electrodes; enzyme activity; herbaceous plants; herbs; hydrogen peroxide; modified carbon paste electrode; ruthenium; ruthenium oxide; ruthenium(IV) oxide; vegetables
• ISSN: 0958-0344; 1099-1565
• DOI: 10.1002/pca.910

A carbon paste electrode containing ruthenium(IV) oxide as a modier was tested as an effective hydrogen peroxide amperometric sensor in bulk measurements (hydrodynamic amperometry). Factors that influence its overall analytical performance, such as pH and the applied potential, were examined. The RuO₂-modied electrode displayed high sensitivity towards hydrogen peroxide, with detection limits as low as 0.02 mm at pH 7.4 and 0.007 mm at pH 9.0. The method was applied for monitoring the decomposition of hydrogen peroxide (by catalase) in phosphate buffer of pH 7.4. The relative response of the electrode towards ascorbic acid was assessed and it was found that the selectivity of the RuO₂-modied electrode towards hydrogen peroxide over ascorbic acid could be signicantly improved by electro-polymerizing m-phenylenediamine on its surface prior to measurements. The RuO₂-modied electrode was used for the kinetic (xed time) determination of catalase activity in the range of 4-40 U/mL (detection limit 1.2 U/mL). The method was applied to the determination of catalase-like activity in various plant materials (recovery ranged from 93 to 101%, detection limit 480 U/100 g).