Determination of percent hemoglobin A1c using a potentiometric method.

We report a potentiometric method for measuring the hemoglobin A1c (HbA1c, glycated hemoglobin) concentration, hemoglobin (Hb) concentration, and percent HbA1c (%HbA1c) in human blood hemolysate. The %HbA1c is important for diagnosis and management of diabetes mellitus. Alizarin red s (ARS) is used as a redox indicator. Phenylboronic acid (PBA) binds to both ARS and HbA1c via diol-boronic acid complexation. The binding of PBA to ARS shifts its redox potential negatively. However, when HbA1c competes with ARS for PBA binding, the solution potential shifts positively. This shift is linked to the HbA1c concentration. The concentration of Hb is determined by allowing it to react with Fe(CN)(6)(3-). The potential shift arising from the reduction of Fe(CN)(6)(3-) by Hb is proportional to the logarithm of the Hb concentration. The results obtained for %HbA1c in human blood hemolysate are in good agreement with those determined using a reference method.