초록 ▼

General classes of 2-thiazolyl tetrazolium salt compounds have been found to be characterized by a reflectance spectrum exhibiting an extended plateau above about 600-650 nm. Such compounds are useful as chromogenic indicators for reducing substances such as NADH. The reflectance plateau confers imp

General classes of 2-thiazolyl tetrazolium salt compounds have been found to be characterized by a reflectance spectrum exhibiting an extended plateau above about 600-650 nm. Such compounds are useful as chromogenic indicators for reducing substances such as NADH. The reflectance plateau confers improved accuracy to analytical assays, particularly for the determination of analytes of medical diagnostic significance, in which a colorimetric response on a reagent carrier matrix is measured by reflectance.

대표청구항 ▼

In a method for determining an analyte in a liquid sample wherein the sample is contacted with a test device comprising a solid carrier matrix incorporated with a test composition comprising (a) reagents which react with said analyte to produce a reducing substance and (b) an indicator compound whic

In a method for determining an analyte in a liquid sample wherein the sample is contacted with a test device comprising a solid carrier matrix incorporated with a test composition comprising (a) reagents which react with said analyte to produce a reducing substance and (b) an indicator compound which is reduced by said reducing substance to produce a chromogenic dye product, and where the chromogenic dye product is measured by irradiating the carrier matrix with a light source having a central wavelength above about 600 nm which wavelength will vary due to manufacturing variances and temperature dependence of the light source and sensing the reflectance of the carrier matrix by measuring reflected light with a detector element, the improvement which comprises employing as said indicator compound a thiazolyl tetrazolium salt of the formula: [Figure] wherein (a) R1 and R2 together form a benzo ring, said benzo ring being substituted or unsubstituted, or (b) R1 is carboxyl, carbalkoxy, carbaryloxy, carbomyl or cyano, and R2is alkyl or chloro, or (c) R1 is alkyl or aryl, and R2 is carboxyl, carbalkoxy, carbaryloxy, carbamoyl or cyano, or (d) R1 is di- or trifluoroalkyl wherein the fluoro substituents are on the carbon adjacent to the thiazolyl residue in the formula, and R2 is chloro, or (e) one or both of R1 and R2 are substituted or unsubstituted phenyl, and if only one is substituted or unsubstituted phenyl, the other is hydrogen or alkyl; and wherein R3 is aryl or styryl, R4 is aryl, and Xo is a counteranion wherein the tetrazolium salts are further characterized in that when they are reduced by the reducing substance to their corresponding formazan the reflectance of the formazan varies by less than 17% over a wavelength range of 50 nanometers at wavelengths of 600 nanometers or greater.