To detect the solid content of polyacrylamide, you can follow the steps below:

1. Weigh an empty, clean, and dry container or crucible accurately and record its weight (W1).

2. Add a known amount of polyacrylamide sample to the container.

3. Place the container with the sample in an oven set to a specific temperature (usually around 105-110°C) for a specific time (typically 1-2 hours). The aim is to evaporate the moisture and volatile components from the polyacrylamide.

4. After the specified time, remove the container from the oven and allow it to cool in a desiccator.

5. Once the container has reached room temperature, weigh it with the dried sample and record its weight (W2).

6. Calculate the solid content using the formula:

Solid Content (%) = [(W2 - W1) / (W2 - container weight)] × 100

Where:

- W1 is the weight of the empty container.

- W2 is the weight of the container with the dried polyacrylamide sample.

- The container weight is the weight of the container itself, which should be subtracted to obtain the net weight of the dried sample.

This method provides an estimation of the solid content of polyacrylamide based on the weight loss after drying. Keep in mind that the drying conditions and time can vary depending on the specific requirements of polyacrylamide and the application for which it will be used.