A kit for the determination of transaminase present in body fluid having a first reagent containing aspartate, a second reagent containing alanine, and a third reagent containing 2-oxoglutarate substrate in combination with a secondary reaction system containing reduced nicotinamide adenine dineucleotide.

Food or chemical allergy and intolerance is determined by comparing an analysis for a given analyzable constituent of a polymorphonuclear leukocyte with and without incubation with the incriminated food or chemical. Allergy or intolerance to the food or chemical under consideration causes the leukocytes to break down releasing the analyzable constituent and permitting its presence to be determined.

An improvement in a method for determining a substance present in a biological fluid by oxidizing a compound produced in the course of the determination in the presence of a dehydrogenase enzyme with the simultaneous production of reduced beta-nicotinamide adenine dinucleotide in an amount proportional to the content of the substance in the fluid, which fluid also contains an endogenous material which or a derivative of which produced during the determination likewise is oxidized in the presence of the enzyme with the simultaneous production of reduced beta-nicotinamide adenine dinucleotide, thereby interfering with the determination, which improvement involves first carrying out the oxidation-reduction reaction of the endogenous material or its derivative, then oxidizing the resulting reduced beta-nicotinamide adenine dinucleotide in the presence of lactate dehydrogenase with the simultaneous reduction of pyruvate to lactate, thereafter inhibiting the lactate dehydrogenase enzymatic activity, and thereafter producing a quantity of the aforesaid compound produced in the course of the determination for conducting the oxidation-reduction reaction therewith without interference caused by the endogenous material or the lactate dehydrogenase. Substances which may be determined include alpha-amylase, transaminases, and triglycerides. A two-reagent combination is employed for the determination.

An improvement in a method for determining glutamate oxalacetate transaminase or glutamate pyruvate transaminase present in a biological fluid, in which method L-glutamate is produced from alpha-ketoglutarate by transamination in the presence of the transaminase in the fluid, and the L-glutamate is oxidatively deaminated in the presence of glutamate dehydrogenase with the simultaneous production of reduced beta-nicotinamide adenine dinucleotide in an amount proportional to the content of the transaminase in the fluid, such fluid also containing an endogenous substance which is oxidized in the presence of glutamate dehydrogenase with the simultaneous production of reduced beta-nicotinamide adenine dinucleotide, thereby interfering with the determination. The improvement for obviating the interference caused by the endogenous substance includes oxidizing the endogenous substance in the presence of glutamate dehydrogenase with the simultaneous reduction of beta-nicotinamide adenine dinucleotide, oxidizing the reduced beta-nicotinamide adenine dinucleotide in the presence of lactate dehydrogenase with the simultaneous reduction of pyruvate to lactate, thereafter inhibiting the lactate dehydrogenase activity, and thereafter producing a quantity of L-glutamate from alpha-ketoglutarate by the aforesaid transamination for oxidative deamination thereof and simultaneous production of reduced beta-nicotinamide adenine dinucleotide in an amount proportional to the content of the transaminase in the fluid. A reagent combination is employed for the determination.

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.