HbA1c can be measured by different methods. But high performance liquid chromatographic (HPLC) methods are considered as a gold standard method for measuring HbA1c in human blood.
A chemical (electrical) charge is present on the molecule of HbA1c, and the amount of the charge differs from the charges on the different components of hemoglobin. The molecule of HbA1c has a difference in size from the other components. HbA1c may be separated by charge and size from the other hemoglobin A components in blood by HPLC. HPLC separates mixtures into their various components by adding the mixtures to special liquids and them under pressure through columns filled with a material that separates the mixture into its different component molecules.