when preparing the protein standards we used a tube tube without protein but including bradford reagent and an equivalent volume of 0.15 m nacl instead of protein. can we just use plain water to prepare tube t instead?
At first, I would like to clarify that preparation the protein standards, according to protein assay by Bradford method, covers preparation a serial dilution of the protein sample with known concentration. For this purpose it is usually used BSA (Bovine Serum Albumin) diluted in 0.15M NaCl from 0 concentration (blank= NaCl only) to the necessary concentration. 0.15 M NaCl corresponds to the physiological normal state (pH 7.4), that is why it is not advisable to use water as the conditions for the protein standards should be the same as for the experimental proteins.