The Bicinchoninic Acid (BCA) assay is a widely used colorimetric method for determining total protein concentration in a sample. This measurement is crucial in fields such as biochemistry, protein purification, clinical diagnostics, and biotechnology, where accurate protein quantification is essential for downstream experiments or quality control. The ease of performing the assay, its sensitivity, and the relative stability of the colorimetric endpoint make this method valuable for routine protein measurements. The BCA method relies on the reduction of Cu²⁺ to Cu¹⁺ by peptide bonds under alkaline conditions, followed by the formation of a purple-colored complex between BCA and Cu¹⁺. The intensity of this purple color, measured at 562 nm, is directly proportional to the protein concentration. Because this reaction is highly specific and stable, the BCA assay is both reliable and reproducible, making it a standard choice for protein quantification.