1. Preselection. The particle size of cation exchange resin is generally controlled at 20-35 meshes, and some can reach 50 meshes. Therefore, before use, drying, crushing and sieving should be carried out first. Usually, drying can be carried out in an oven, or in a dryer containing phosphorus pentoxide, calcium oxide or concentrated sulfuric acid. The crushing should not be too fine, otherwise the experimental yield will be affected.

2. Pretreatment. Strongly alkaline cation exchange resin should be treated with 4% sodium hydroxide aqueous solution 20 times the volume of the resin (the resin is converted to OH type), then washed with 10 times the volume of water, and then treated with 10 times the volume of 4% hydrochloric acid (the resin is converted to chlorine type), finally washed to neutral with distilled water, then converted from chlorine type to OH type, then converted to chlorine type, and finally treated with 10 times the volume of 4% sodium hydroxide aqueous solution. The weakly alkaline cation exchange resin only needs to be washed with 10 times of distilled water, without washing to neutral.

3. Install the column. Put the treated resin in the beaker, add water and fully stir to remove the bubbles, and stand for a few minutes until most of the resin settles, then pour out the upper muddy particles; The column can be installed after repeated operation until the upper liquid is clear. Pay attention to placing 1cm thick glass wire at the bottom of the column, flattening it with a glass rod, pouring the resin into the column, and paying attention to preventing bubbles.

4. Resin exchange. Prepare the sample into an aqueous solution of a certain concentration and pass it through the column at a proper flow rate. The sample solution can also be repeatedly passed through the column until the component exchange is complete. Use color method to check whether the components are completely exchanged.

5. Resin elution. Note that the components with weak affinity are washed first. The commonly used cation exchange resin eluents include strong acids, strong alkalis, salts, buffer solutions with different pH, organic solutions, etc. Gradient elution or single concentration elution can be selected.

6. Resin regeneration.