SDS-PAGE is a qualitative method to detect protein, but the protein bands on the map cannot be accurately quantified.

Usually, only some control samples can be used to compare the number of protein bands on the analysis map.

For example, a sample with known protein amount (BSA) and a sample to be detected run in a nearby swimming lane, and the amount of the sample to be detected can be estimated by comparing the size, color and depth of the stained sample.