Test used to differentiate maternal from fetal blood?

Apt test or Singer's alkali denaturation test is used to differentiate between fetal and maternal blood. It is based on the principle that fetal Hb is more resistant to alkali denaturation. Thus, when eater and the blood are mixed with sodium hydroxide, it remains pink for longer if foetal in origin. If it is maternal blood, it turns yellow brown in 2 min, as adult Hb is denatured easily.Kleihaur Betke test is performed on maternal blood to assess the amount of fetomaternal bleed.The osmotic fragility test (OFT) is used to measure erythrocyte resistance to hemolysis while being exposed to varying levels of dilution of a saline solution.Conditions associated with increased osmotic fragility include Hereditary spherocytosis, Autoimmune spherocytosis, Poisoning, Severe burns. Conditions associated with decreased fragility: Thalassemias, Iron deficiency anemia, Sickle cell anemia. Reference : page 138 and 311 Textbook of Obstetrics Sheila Balakrishnan 2nd edition