To detect the ionicity of polyacrylamide, you can use the following method:

1. Conductivity measurement: indirectly determine the ionicity of the polyacrylamide solution by measuring its conductivity. Conductivity is related to changes in ion concentration in a solution. Highly ionic polyacrylamide solutions usually have higher conductivity.

2. Ion-selective electrode: Use ion-selective electrodes, such as pH electrodes or ion-selective electrodes (such as sodium ion electrodes, ammonium ion electrodes, etc.), to directly measure the concentration of specific ions in the solution. This can be used to determine the concentration of ions in a polyacrylamide solution and thus infer the ionicity.

3. Ion exchange chromatography: Use ion exchange chromatography to determine the ion concentration in the polyacrylamide solution. This method uses an ion exchange resin to adsorb ions from solution and determines the concentration of individual ions through varying elution conditions.

4. Thermogravimetric analysis (TGA): Thermogravimetric analysis can be used to measure the thermal decomposition behavior of polyacrylamide. Polyacrylamides with higher ionicity generally decompose faster at high temperatures, while polyacrylamides with lower ionicity have higher thermal stability.

These methods can help determine the ionicity of polyacrylamide. However, specific test methods may need to be appropriately adjusted and optimized based on actual needs and available equipment. In actual operation, it is best to refer to relevant standard methods or consult professional laboratory technicians.