A high-throughput method for measurement of glycohemoglobin in blood samples utilizing laser-accelerated proteolysis and MALDI-TOF MS.

Abstract

Glycosylated hemoglobin A1c (HbA1c) is a useful marker for the diagnosis of diabetes mellitus. Commercial column separation methods for HbA1c measurement were lacking throughput and sometimes interfered with hemoglobin variants. In this work, we developed a high-throughput and specific method for HbA1c by quantitative measurement of N-terminal peptides (NT method). Two thousand specimens could be measured in 8 h. The high-throughput was achieved by using a fast analysis of matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) and an efficient proteolysis accelerated by laser irradiation. An intensity ratio of glycosylated to non-glycosylated hemoglobin N-terminal peptides was used to calculate the HbA1c level in blood. Interference from Hb variants of N-terminal peptides could be excluded by a highly accurate mass selection. The coefficient of variation (CV) of intra-assay precision was 9.8 and 9.9%, respectively. The CVs of inter-assay precision over 20 days were 9.1 and 8.4%, respectively. Measurement results were well correlated with the commercially available column method (r = 0.995). The NT method is promising for large-scale screening for diabetes mellitus among people.