BCA Protein Assay kit provides an ultra-sensitive method to detect and quantify total protein concentration even in the presence of detergents. The Kit has been optimized for determining total protein content in low protein concentration samples (0.5-40 μg/ml). The assay is based on the reaction of bicinchoninic acid (BCA) with the cuprous cation (Cu+1), which is generated by reduction of cupric cation (Cu+2) with the protein in alkaline conditions. The Cu+1-BCA chelate is a water-soluble complex and exhibits a strong absorbance at 562 nm that is linear over a concentration range of 0.5-40 μg/ml. In general, protein concentrations are estimated with reference to a commonly used protein standard. The Kit includes Bovine Serum Albumin (BSA) as a protein standard for estimation of total protein content of samples.