Determines the concentration of total protein present in a sample. Proteins are purified by acid precipitation, minimizing interference to the assay from predict chemicals. Results are expressed as mg of total protein extracted mg/gm of sample, mg/dm2 as a per surface area. The greater the number, the greater the amount of protein present. The difference between the Bradford and the Lowry is that they are based on the recognition of different amino acids and are affected by different interfering substances.