INHIBITIVE KINETIC SPECTROPHOTOMETRIC DETERMINATION OF PROTEIN

摘要

A novel inhibitive kinetic spectrophotometric method for the determination of protein is proposed based on the principle that serum albumin (SA) has an inhibitive effect on the oxidation discoloring of p-acetylchlorophosphonazo (CPApA) by potassium periodate in the medium of 4.0 X 10~(-4) mol/L H_(2)SO_(4) at 100 deg C. The maximum absorption peak of SA - CPApA - KIO_(4) system is located at 550 nm. The absorbance difference ((DELTA)A) is linearly related with the concentration of SA over the range of 0.80-7.50(mu)g/mL at the wavelength and fitted the equation: (DELTA)A velence 0.064C (C: (mu)g/mL)-0.0173, with a correlation coefficient gamma velence 0.9973. The detection limit of the method was 0.30 (mu)g/mL. The method was successfully used to determine protein content in milk and milk powder samples and the determined results were in good agreement with those of tribromoarsenazo spectrophotometry. The relative standard deviation for 13 replicate determinations of the method was 3.64-3.76percent. The standard addition recovery of the method was 99.50-101.6percent.