The anticoagulant of choice for performing coagulation studies is-

I. Calcium chelating agents * Ethylene diamine tetraacetic acid (EDTA):- RBC count, total leucocyte count, eosinophil count, platelet count. Hemoglobin, HbF estimation, and Hb electrophoresis. * Double oxalate (mixtures of ammonium oxalate and potassium oxalate):- Since the morphology of the blood cells is not well preserved, it is now replaced by EDTA * Sodium citrate solution:- Coagulation studies, ESR by Westergren method, blood bank {ACD (acid citrate dextrose) solution was used and now replaced by citrate phosphate dextrose adenine (CPDA)} *Sodium fluoride:- Estimation of blood sugar II. Heparin:- Osmotic fragility test, red cell enzyme studies (e.g. G6PD and PK deficiency), electrolyte estimation, aerial blood gas analysis. Ref: RAM DAS NAYAK 2nd Ed. Pg no:336