Comparative analysis of the spectrophotometric methods of the protein amount determination in the pectic polysaccharide samples

摘要

To analyze the reliability of determining the weight fraction of protein in the samples of pectic polysaccharides by the optical density of solutions in the ultraviolet and visible regions of the spectrum, a comparison of eleven methods: Flores, Lowry, Bradford, Sedmac, Ruhemann (ninhydrin reaction) methods, ultraviolet spectrophotometry, methods with Benedict reagent, with Nessler reagent, with amide black, with bicinchoninate reagent, and the biuret method has been carried out. As a result, the insufficient sensitivity of seven of the listed methods has been found, which does not recommend them for these purposes. The Lowry, Bradford, Sedmac methods, and the method with the Nessler reagent can be used for the determination of protein content in the samples of pectic polysaccharides, and the Bradford method can be recommended for characterization of samples of pectic polysaccharides if the weight fraction of protein does not exceed 15%, and the Lowry method can be used for the samples with the weight fraction of protein greater than 15%.