Difference and application of blood anticoagulant EDTA dipotassium and Tripotassium

Blood anticoagulants, EDTA dipotassium and EDTA Tripotassium, are common anticoagulants in blood vessels. The anticoagulant principle is to use EDTA to chelate Ca ion in blood, so as to prevent coagulation reaction and achieve anticoagulant effect. Because of the difference of one potassium atom in chemical composition, they are different in application.
International Committee for hematology standardization and NCCLS (CLSI) recommend K2 EDTA as a special anticoagulant for blood cell count and volume measurement. The reasons are as follows:
● if the concentration of EDTA increases, K3 EDTA is more likely to cause erythrocyte shrinkage than K2 EDTA. (when the concentration of K3 EDTA reaches 7.5mg/ml, 11% of red blood cells will shrink.)
● if the specimen is placed for a period of time, K3 EDTA is more likely to cause the problem of cell volume increase than K2 EDTA (4 hours, 1.6% increase in volume)
● K3 EDTA is more likely to reduce the mean corpuscular volume (MCV) than K2 EDTA (usually with a negative deviation of - 0.1 to - 1.3% compared with K2 EDTA)
● if K3 EDTA is used as a liquid additive, it will cause dilution of the sample. All direct test items, such as hemoglobin, red blood cell, white blood cell and platelet count, are 1-2% lower than K2 EDTA as anticoagulant.

● using some analytical instruments, K3 EDTA will reduce the white blood cell count at a higher concentration. Brunson et al reported that the plastic K2 EDTA tube has a good consistency with K3 EDTA glass tube in the detection of cell count and classification. However, as shown before, 1-2% error due to dilution is also reported.
There are differences in the pH value environments in which two and three potassium are stable. The pH of EDTA two potassium should be controlled in a weak acid environment of 2.7-6.2, the pH of its aqueous solution should be about 4.8, and the pH of EDTA three potassium should be controlled in a weak alkaline environment of 6.2-10.2, usually the pH of its aqueous solution should be about 7.5. In terms of solubility, the solubility of Tripotassium EDTA is higher than that of dipotassium, and that of dipotassium is higher than that of disodium.
Since 2005, Desheng technology has developed and produced in vitro diagnostic reagents, such as separation gel, heparin, EDTA potassium salt, etc. it has a deep research on new Trinder's reagents, bicine, Tris and luminol, acridine ester and other biobuffers such as chromogenic substrate TOS, Maos, etc., and has a professional advantage in independent research and development and synthesis.