Abstract: A method for determination of an analyte in a sample containing reducing substances is disclosed. After the decomposition of the reducing substances by reaction with hydrogen peroxide formed by enzymatic Redox reaction using a component in the sample which does not participate in another enzymatic Redox reaction using the analyte, the remaining hydrogen peroxide is decomposed, and then the analyte is subjected to enzymatic Redox reaction to form hydrogen peroxide which is then determined by a known method.

Abstract: A method for decomposing hydrogen peroxide is disclosed. The hydrogen peroxide is reacted with a compound represented by the formula (I) ##STR1## wherein Z represents OH or NR.sub.4.R.sub.5 wherein R.sub.4 and R.sub.5 are the same or different and represent hydrogen, alkyl, substituted alkyl or acyl, and R.sub.1,R.sub.2 and R.sub.3 are the same or different and represent hydrogen, halogen, alkyl, alkoxy, amino, nitro, carboxyl or sulphonyl, in the presence of peroxidase.

Abstract: A method of and reagent for determining hydrogen peroxide, in which the hydrogen peroxide containing sample is treated with a colouring reagent comprising a peroxidase, a hydrogen donor and an electron or radical acceptor which react stoichiometrically with the hydrogen peroxide to produce a pigment which is then measured colorimetrically. In accordance with the invention the hydrogen donor is specifically a compound of the formula ##STR1## where R.sub.1 is CH.sub.3, C.sub.2 H.sub.5, CH.sub.2 OH, CH.sub.2 CH.sub.2 OH, CH.sub.2 CH.sub.2 NH.sub.2 or COCH.sub.3 ;R.sub.2 is CH.sub.2 OH, CH.sub.2 CH.sub.2 OH, CH.sub.2 CH.sub.2 NH.sub.2, CH.sub.2 NHCOCH.sub.3, CH.sub.2 CH.sub.2 NHCOCH.sub.3 or COCH.sub.3 ;R.sub.3 is H, CH.sub.3, C.sub.2 H.sub.5 or OCH.sub.3 ; andR.sub.4 is H or CH.sub.3.