Hb F - 1 
Quantitation by alkali denaturation:
Most adult hemoglobins are denatured when exposed to strong alkaline solutions but Hb F is not. When ammonium sulfate is added it stopps the denaturation process and precipitates the denatured hemoglobins. Hb F remains in solution and can then be measured.
Quantitation by acid elution: (betke-Kleihauer)
Adult hemoglobins are eluted from red cells  when exposed to strong acid solutions but Hb F is not. The red cells are then stained and the number of Hb F containing red cells can then be determined