Which method is preferred for HbA1c determination?

• A. Affinity chromatography
• B. Immunoassay
• C. HPLC
• D. Capillary electrophoresis

Answer: (A)

Glycated hemoglobin (HbA1c) can be isolated from the bulk of Hb by exploiting the chemical feature that defines HbA1c: the glucose moiety has cis-diols that can form reversible complexes. Affinity chromatography using boronate-containing resin specifically binds these cis-diols, capturing HbA1c while non-glycated Hb passes through. After washing, HbA1c is eluted and quantified, giving a direct readout of the glycated fraction that reflects average blood glucose over ~3 months.

This approach is practical for routine use because it directly targets the glycation tag rather than relying on changes in charge or antibody recognition. It tends to be robust across common hemoglobin variants and is amenable to automation, making it convenient for high-volume testing. While other methods like immunoassays or HPLC can be very precise, affinity chromatography offers a straightforward separation mechanism that specifically isolates the glycated component, which is the key to obtaining HbA1c values that correlate with long-term glycemic control.