| abstract |
A method of determining the presence or concentration of a peroxidatively active substance, such as hemoglobin, in a test sample is disclosed. The method comprises contacting the test sample with an indicator reagent composition which interacts with the peroxidatively active substance to produce a measurable or detecable color change. The indicator reagent composition comprises a redox indicator dye, a hydroperoxide, a ferric ion and a phosphorous compound having the formula <IMAGE> wherein R1 or R2 are certain substituted or an unsubstituted aromatic moieties or certain polyhydric compounds, and wherein X is O, S or NH. The assay can be performed in wet phase or the composition can be incorporated into a carrier matrix. The method provides a more accurate and trustworthy assay of a test sample for a peroxidatively active substance and is especially useful in the assay of urine for occult blood. |