DETERMINATION OF ALBUMIN AND GLOBULIN AT NANOGRAM LEVELS BY A RESONANCE LIGHT-SCATTERING TECHNIQUE WITH A,BETA,GAMMA,DELTA-TETRAKIS(4-SULFOPHENYL)PORPHINE

A method for determination of bovine serum albumin (BSA) and gamma-glo bulin (gamma-IgG) at nanogram levels is proposed by using a common spe ctrofluorometer to detect the intensity of resonance light-scattering. In the presence of BSA or gamma-IgG at pH 1.86 and ionic strength 0.0 4, the aggregation of a,beta,gamma,delta-tetrakis(4-sulfophenyl)porphi ne (TPPS4) was observed. It was found to result in strong enhanced res onance light-scattering (RLS) signal with a scattering peak at 490.0 n n. But at pH 1.86 and ionic strength 0.11, only BSA can induce the agg regation of TPPS4 resulting in the strong enhanced RLS. Determination for synthetic samples by making use of the effect of ionic strength sh owed that if the ratio of gamma-IgG in the mixture of gamma-IgG and BS A is lower than 0.20, the results for the simultaneous determination o f BSA and gamma-IgG fractions without separation are satisfactory, but if the content of gamma-IgG in the mixture is too high, the determina tion error is significant. However, the total content of BSA and gamma -IgG in human serum can be determined with results identical to those obtained according to the Bradford method using CBB G-250.