Patent ID: 7226790

Claim:
A method of measuring an analyte in a sample using a redox reaction, comprising: aging a solution containing a tetrazolium compound and sodium azide at a temperature of at least 20° C. and not higher than 60° C. for 6 to 120 hours; then adding the aged solution to the sample; measuring an amount of a reducing substance or an oxidizing substance derived from the analyte in the presence of the tetrazolium compound and the sodium azide using the redox reaction; and determining an amount of the analyte from the amount of the reducing substance or oxidizing substance thus measured, wherein the tetrazolium compound (A) and the sodium azide (B) are present at a ratio (molar ratio A:B) in a range from 20:3 to 20:12, and the analyte is at least one selected from the group consisting of glycated proteins, alycated peptides, and glycated amino acids.