Systematic comparisons of various spectrophotometric and colorimetric methods to measure concentrations of protein, peptide and amino acid: Detectable limits, linear dynamic ranges, interferences, practicality and unit costs

► For proteins, Bradford method was most sensitive with widest detectable range. ► Peptides could be measured by A205, A280, BCA, Lowry and Ninhydrin methods. ► For amino acids, A205 had a wider detectability range compared to Ninhydrin method. ► Biuret method offered the widest linear dynamic range (LDR) for proteins. ► A280 and Ninhydrin had the widest LDR for peptides and amino acids, respectively.