Preparation of lead acetate saturated solution (related to USP standards)
1. Preparation of raw materials
An appropriate amount of lead acetate ($Pb (CH_3COO) _2 $) should be prepared. The purity should meet the relevant quality requirements, and high-quality distilled water should be selected to ensure the purity of the solution.

2. Preparation steps
1. ** Dissolution operation **: In a clean container, put an appropriate amount of distilled water. According to the relevant USP guidelines, slowly add lead acetate powder, and continue to stir at a uniform speed with a glass rod. This process should pay attention to the addition rate, not too fast, so as to avoid lead acetate agglomeration and affect the dissolution effect.
2. ** Heating assistance (if necessary) **: If the dissolution rate is too slow at room temperature, the solution can be moderately heated according to USP regulations. During the heating process, the temperature needs to be strictly controlled, not too high, and continuous stirring is required to promote the full dissolution of lead acetate.
3. ** Determination of saturation state **: Continue to add lead acetate and stir until a small amount of lead acetate in the solution no longer dissolves, and is suspended or precipitated in tiny particles at the bottom of the container. At this time, it can be judged that the solution has reached a saturated state.
4. ** Let stand and filter (if required) **: According to USP standards, if further treatment is required, let the saturated lead acetate solution stand for a period of time to precipitate the insoluble matter that may exist. Subsequently, a suitable filter paper or filter is filtered to remove insoluble impurities, and the obtained filtrate is a saturated solution of lead acetate.

Third, storage points
Transfer the prepared saturated solution of lead acetate to a clean, well-sealed container. According to the relevant storage specifications of USP, store in a cool, dry and dark place to prevent the stability and concentration of the solution from being affected by factors such as light and temperature changes.