EDTA disodium can coordinate with most metal ions to form a very stable cyclic chelate. Due to its stoichiometric coefficient of chemical reaction with metal ions generally being 1:1, it is more convenient to calculate, which is also one of the reasons why it is widely used. EDTA disodium salt is an abbreviation for ethylenediaminetetraacetic acid disodium salt. It appears as a white crystalline powder, odorless, non-toxic, low hygroscopicity, soluble in water, and has a saturated solution concentration of about 0.3mol/L at room temperature. It is usually prepared into a standard solution of 0.01-0.1mol/L for titration analysis. In order not to affect the accuracy of EDTA disodium standard solution, we should pay attention to the following points during the configuration process: 1. When weighing samples, attention should be paid to accurate dosage to avoid errors during configuration; 2. The solution used in the analysis experiment should be prepared with pure water, and the container should be washed with pure water at least three times; 3. When shaking well, the bottle mouth should be tightly closed and attention should be paid to the tightness of the bottle stopper to avoid leakage and loss; 3. The prepared solution cannot be placed in a regular glass bottle, as the Ca2+and Mg2+in the bottle will react with EDTA and affect the results. It is best to use a polyethylene bottle or a hard glass bottle; 4. When using the calibration method to prepare EDTA disodium standard solution, attention should be paid to the quality of distilled water. If the water contains Ca2+, Mg2+, Al3+, Fe3+plasma, it will consume titrant or blocking indicator, which will affect the results.