Hemoglobin electrophoresis is the movement of hemoglobin proteins in an electric field at a fixed pH. Because the various hemoglobins are comprised of different combinations of globin chains (normal or abnormal), they will demonstrate different degrees of mobility.
Typically, when a thalassemia or hemoglobinopathy is suspected, an alkaline hemoglobin electrophoresis is performed. For an alkaline electrophoresis, a hemolysate is applied to cellulose acetate, which is then electrophoresed in a buffer at pH 8.4-8.6. At this pH hemoglobin proteins move from cathode to anode. The proteins are visualized by the application of a dye, which also makes them measurable by densitometry.
The results of the alkaline electrophoresis can be confirmed with acid electrophoresis. The image below compares the migrations and some bands of acid and alkaline electrophoresis. image: http://pathologyapps.com/label/hemoglobin-gel-migration.jpg
