Spectrophotometric Method for the Determination of Total Proteins in Egg White Samples

The present study describes a modified version of the Biuret method, used for the determination of proteins. The Biuret reaction is based on the formation of a complex between cupric ions and protein. This procedure is developed for the determination of proteins in egg white samples, without addition of KI as reagent. KI is added to prevent autoreduction and separation of cuprous oxide and to mask the presence of such impurities. The optimum conditions for proteins quantification, using ovoalbumin and BSA (Bovine serum albumin) as standard proteins were studied. Under the optimized experimental conditions, Beer's law is obeyed over the concentration ranges of 0.22-1.98mg/mL and 0.15-1.35mg/mL for ovoalbumin and BSB, respectively. Method validation has been demonstrated through a variety of tests for linearity, accuracy, precision, LOD and LOQ. The obtained results from spectrophotometric and literature methods were statically compared.