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A chemiluminescent method for the simultaneous assay of peroxidase and catalase activities and chemical traps and quenchers of free radicals in natural samples, based on the additions of peroxidase standards, is presented. The method was standardized with horseradish peroxidase and beef liver catalase. The theoretical basis, mathematical treatment and computer processing of the method are described. The technique was used to analyse 25 samples of various common fruits and vegetables. The levels of peroxidase activity thus determined were compared with those obtained using the guaiacol method and were found to be in good agreement. The relationship between the shape of the chemiluminescent curves and the proportions of peroxidase and catalase activities and traps and quenchers are discussed.

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The determination of aromatic amines and phenols by an enzyme pO2 electrode containing cross-linked ceruloplasmin in the reaction layer was examined. The electrode shows at pH 5.5 a marked selectivity for derivatives with-NH2 or NR2, resp., and -OH-groups in para and ortho position while its sensitivity for aromatic diamines is better than its sensitivity for aminophenols and polyphenols. p-Phenylenediamine and its N,N-dialkyl derivatives are the best analytes which can be detected starting from concentrations of 10-5 mol l-1 and higher; the reproducibility is 5-7% at an electrode response time of 2-5 min.