The protein quantification method using bicinchoninic acid (BCA) has been described for the first time in 1985. The method is based on the reaction between peptide bonds and four particular amino acids (cysteine, cystine, tryptophan and tyrosine) with copper. Consisting in two reactions, only one reagent addition is required. The quantification of proteins by BCA is advantageous because there is less interferences with contaminants or buffer components compared to the Folin-Ciocalteu reagent and specially with detergents.