During protein purification, the concentration of the protein in the solution should be determined. Colorimetric methods are generally used to determine the protein concentration in the purified sample. The amount of this coloured product is then measured spectrometrically, and the amount of colour related to the amount of protein is present by appropriate collaboration.

Various methods to estimate protein are as follows:

1. UV absorption method
2. Lowry’s method
3. Bradford’s method
4. Biuret method
5. Kjeldhal’s method