1. Prepare 0.5% horseradish peroxidase solution: dissolve 0.5g horseradish peroxidase in 100 mL phosphate buffer (PBS) and filter with filter paper to remove insoluble particles.

2. Preparation of stock solution: dilute the above 0.5% HRP solution with PBS according to the ratio of 1:9 to obtain a stock solution with the time of 100, which can be stored separately in the refrigerator for later use.

It should be noted that when using HRP, it is necessary to ensure its activity, so the following points should be noted:

1. When preparing the stock solution, ensure that there are no particles in the solution, otherwise it will affect the use effect.

2. The prepared stock solution should be packaged and stored in the refrigerator to prolong its service life.

3. When using the stock solution, it should be diluted according to the required concentration to avoid being exposed to the air for a long time, so as not to affect its activity.

4. Avoid using expired stock solution, otherwise it will affect the experimental results.

In a word, the method of preparing and preserving HRP mother liquor needs to follow certain steps and precautions to ensure the activity of enzyme and the accuracy of experimental results.