Patent ID: 8318501

Claim:
A method for directly assaying percentage of glycated hemoglobin A1c in a blood sample without measuring the total hemoglobin in the blood sample in a separate process, said method comprising: a) contacting protein fragments containing glycated peptides or glycated amino acids with a fructosyl amino acid oxidase to generate hydrogen peroxide (H 2 O 2 ), wherein the protein fragments are generated by contacting the blood sample with 1) a lysing buffer which releases hemoglobin from red blood cells in the blood sample; 2) a first oxidizing agent which selectively oxidizes low molecular weight reducing substances; 3) a second oxidizing agent which selectively oxidizes high molecular weight reducing substances, and 4) a protease which digests glycated hemoglobin into glycated peptides or glycated amino acids; b) contacting H 2 O 2 generated in step a) with a color forming substance in the presence of a peroxidase to generate a measurable signal; and c) determining percentage of glycated hemoglobin A1c in the sample by correlating the measured value from the generated signal in step b) to a percentage of glycated hemoglobin A1c in a calibration curve without measuring the total hemoglobin in the blood sample separately.