NaOH 20 %
CuSO4.5H2O 25 %
K2HPO4 Μ/15 pH= 4.5


  • Prepare standard solutions Bovine Serum Albumin-B.S.A. (concentration 0 -10 mg/ml). Transfer 1 ml of each standard solution in test tubes.
  • Add in each test tube 3 ml NaOH 20 % and 0.75 ml K2HPO4 Μ/15 pH=4.5.
  • Boil the samples for 5 min and then cool them at room temperature.
  • Add 0.125 ml CuSO4.5H2O 25 % and incubate at room temperature for 10 min. During incubation the samples were agitated periodically with vortex.
  • Centrifuge the samples for 20 min at 4000 rpm.
  • Measure the absorption (A) of each sample at λ= 540 nm.
  • Draw the standard curve.
  • In centrifuge tubes put 5-10 mg of dry biomass which contains 1.5-8 mg protein.
  • Measure the absorption of the unknown samples and define protein’s concentration using the standard curve.


Notation: In case that biomass contains significant amount of lipids, extraction of lipids with organic solvents should take place before determination of cellular protein.