Resonance light-scattering method for the determination of BSA and HSA with sodium dodecyl benzene sulfonate or sodium lauryl sulfate

A new resonance light-scattering (RLS) assay of proteins such as bovine serum albumin (BSA) and human serum albumin (HSA) is presented. In the medium of phosphoric acid (pH=2.6), the weak RLS of sodium dodecyl benzene sulfonate (SDBS) or sodium lauryl sulfate (SLS) can be greatly enhanced by proteins, owing to interaction between the protein and the anionic surfactant and formation of an associate. The RLS intensity of the SDBS-protein system is stronger than that of the SLS-protein system under same experimental conditions. It is considered that the synergistic resonance caused by the absorption of both protein and SDBS could produce strong RLS, while absorption of protein only in the SLS system could cause relatively weak RLS. The enhanced intensity of RLS is proportional to the concentration of the protein. If SDBS is used as the probe the linear range is 7.5x10(-9)-1.5x10(-5) g mL(-1) for BSA and 1.0x10(-8)-1.0x10(-5) g mL(-1) for HSA. The detection limits are 1.8 and 2.8 ng mL(-1), respectively. When SLS is used as the probe the linear range is 2.0x10(-8)-1.0x10(-5) g mL(-1) and 2.5x10(-8)-1.0x10(-5) g mL(-1) for BSA and HSA, respectively, and the detection limits are 12.8 and 21.6 ng mL(-1), respectively. The biological mimics samples are synthetic concoctions of BSA and HSA with some interferents. In these samples, the concentration of interferents is higher than the concentration normally existing in organisms. The samples were determined satisfactorily.