Ethylenediaminetetraacetic Acid Lead(II) Disodium Salt Hydrate is a stable metal-EDTA chelate complex primarily used as a primary standard in analytical chemistry for complexometric titrations. It serves to standardize EDTA solutions by providing a precise, known quantity of chelated lead(II) ions, enabling accurate determination of metal ion concentrations in samples. This compound is also utilized in calibration of analytical instruments, research on metal chelation and speciation, and studies involving lead toxicity or detoxification in biological and environmental contexts.