The most effective way to quantitate hemoglobin A2 is by?

• A. Column chromatography
• B. Densitometry
• C. Citrate agar electrophoresis
• D. Alkali denaturation test

Answer: (B)

Hemoglobin A2 is a minor component of total hemoglobin, and its diagnostic value lies in accurately quantifying what fraction of the total Hb it represents. After separating HbA2 from other hemoglobins, measuring its amount with a densitometer provides a precise, objective readout by quantifying the band or peak intensity (area) corresponding to HbA2 relative to the total Hb. This direct measurement makes densitometry the most effective way to determine the percentage of HbA2.

Other methods can separate HbA2 but do not inherently provide precise quantitation. Column chromatography can separate fractions but requires additional steps to quantify them. Citrate agar electrophoresis can resolve different Hb species, yet the readout is not inherently quantitative without densitometric analysis. The alkali denaturation test is more of a screening approach than a quantitative measure of HbA2 levels.