US Patent 8003399 Nitrite detection technique

A diagnostic test kit for detecting the presence or absence of nitrites within a test sample is provided. The test kit comprises an aromatic primary amine that is capable of reacting with a nitrite to form a diazonium ion. The test kit also comprises a lateral flow device that comprises a chromatographic medium and an absorbent material that receives the test sample after flowing through the chromatographic medium. The chromatographic medium defines a detection zone within which is contained a detection reagent (e.g., nucleophilic aromatic amine) that is capable of reacting with the diazonium ion to form an indicator (e.g., azo compound). The indicator exhibits a color that is different than the color of the detection reagent.