Use of inhibitors of color generation in chromogenic assays

In a diagnostic reagent system for the detection of an analyte in an aqueous system which analyte is selected from the group consisting of glucose, cholesterol, triglyceride and uric acid which reagent system contains an oxidase specific for the analyte whose presence or concentration is being sought, a chromogenic oxidation indicator which generates a colored response upon being oxidized, a buffer and a peroxidase the improvement which consists essentially of the inclusion in such reagent system of an inhibitor of color generation which is a 1,4-disubstituted semicarbazide of the formula:

• ##STR9## wherein R.sub.1 is an electron withdrawing group and R.sub.2 is allyl, benzyl, or alkyl of 1-6 carbon atoms.

A diagnostic reagent system for the detection of glucose in an aqueous medium which reagent system comprises glucose oxidase, a buffer, a peroxidase and a substituted benzidine as chromogenic indicator together with a di-substituted semicarbazide of the formula:

• ##STR10## wherein r.sub.2 is alkyl of 1-6 carbon atoms, allyl or benzyl and R.sub.1 is an electron withdrawing group, said semicarbazide being present in sufficient amount to inhibit the color formed by oxidation of the substituted benzidiene to facilitate discrimination of the color intensity between different degrees of oxidation of the benzidine.

A reagent pad for the detection of glucose in urine which comprises an absorbant support having absorbed therein glucose oxidase, a buffer, a peroxidase, a benzidine chromogenic indicator and 4-allyl-1-(2-substituted phenyl)semicarbazide.

1,4-disubstituted semicarbazide compounds of the formula:

• ##STR11## wherein R is alkyl of 1-6 carbon atoms, allyl or benzyl and Ar is an electron withdrawing heterocyclic compound or phenyl substituted with an electron withdrawing group.

Semicarbazides of claim 209 selected from the group consisting of 4-methyl-1-phenylsemicarbazide, 4-allyl-1-(4-fluorophenyl)semicarbazide, 4-allyl-1-(4-chlorophenyl)-semicarbazide, 4-benzyl-1-phenylsemicarbazide, 4-benzyl-1-(2-pyridyl)semicarbazide, 4-allyl-1-(2-fluorophenyl)-semicarbazide, 4-allyl-1-(2-chlorophenyl)semicarbazide, 4-allyl-1-(4-methoxyphenyl)semicarbazide, 4-allyl-1-(4-bromophenyl)-semicarbazide, 4-allyl-1-(2-bromo-phenyl)semicarbazide, 4-allyl-1-(4-tolyl)semicarbazide, 4-allyl-1-(2-tolyl)semicarbazide, 4-allyl-1-(3-bromophenyl)semicarbazide and 4-allyl-1-(3-nitrophenyl)semicarbazide.