Dipotassium ethylenediaminetetraacetate is usually referred to as dipotassium EDTA. When purchasing reagents, we will find that it has two CAS numbers. One of these is actually EDTA dipotassium crystalline hydrate, but many people on the Internet confuse the two. , It becomes a mixed use of the two numbers. What is the difference between the two and will it affect the use?
The dipotassium EDTA is CAS 2001-94-7, and the dipotassium EDTA dihydrate is CAS25102-12-9. The difference between the two is that one molecule has two crystal waters. Dipotassium EDTA powder is easy to absorb moisture and become crystal water. It is relatively stable when it contains two crystal waters. For blood anticoagulants, EDTA dipotassium containing crystal water is generally used.
Purchase details of blood anticoagulant EDTA dipotassium
Other anticoagulants such as tripotassium EDTA and sodium citrate have similar situations. In fact, when most salts or other compounds precipitate crystals from aqueous solutions, the crystals often contain a certain number of water molecules, which is crystal water; many mineral salts in nature are more stable when they exist in the form of crystal hydrates.
The number of crystal water of crystal hydrate is usually related to the vapor pressure of water in the environment. As the vapor pressure increases, the number of water molecules also increases. The stability of crystal hydrate is related to temperature, cation and anion. Generally, potassium ions do not have crystal water (dipotassium EDTA and tripotassium EDTA both have crystal water, with exceptions). Sodium ions often have crystal water, such as their carbonates. The number of crystal water in salts is related to temperature, 34 There are 10 crystal waters below ℃, and no crystallization water above 34℃. Some crystal hydrates will automatically lose crystal water in dry air, that is, weathering; some will automatically lose crystal water, deliquescence or moisture absorption.
When used as a blood anticoagulant, EDTA dipotassium or tripotassium both need to be prepared with water to prepare a solution. Whether it contains crystal water will not affect its anticoagulant effect. However, in the test and calculation, the molecular weight of EDTA dipotassium without water and with crystal water is different. Dipotassium without crystal water has stronger moisture absorption and is not as stable as hydrate. If it absorbs moisture, it may cause calculation errors.
Special attention should be paid to the EDTA dipotassium CAS number when purchasing. Don't think that the CAS number is not the same as if the CAS number is inconsistent. Be sure to check repeatedly. The EDTA dipotassium, tripotassium, and sodium citrate produced by Desheng are easy to absorb moisture in the air, so it is sealed and stored. Please pay attention to it when using it.
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