[Determination of serum proteins by resonance light scattering method with lidocaine as a probe]

A new method for the determination of bovine serum albumin (BSA) and human serum albumin (HSA) was developed by using resonance light scattering (RLS) technique via an interaction of serum albumin with lidocaine and sodium dodecylbenzene sulphonate (SDBS). The RLS intensity of serum albumin was enhanced in the presence of lidocaine and SDBS. The influences of some experimental factors, including incubation time, addition sequence of reagents, pH values, foreign substances and the concentrations of lidocaine and SDBS, on the enhancement of the RLS intensity were investigated. Under the optimal conditions, the enhanced RLS intensities were proportional to the concentrations of serum albumin in the range of 1.0-45.0 mg x L(-1) for BSA and 0.5-30.0 mg x L(-1) for HSA. The method was successfully applied to the determination of real human serum samples, with the relative standard deviations of 4.9%-5.7% (n = 5) and standard addition recoveries of 90%-103%. The method only involves the use of conventional fluorescence spectrometer and chemical reagents. It is simple, easy to operate and sensitive with the limit of detection of 0.14 mg x L(-1). The fresh human serum samples can be directly analyzed without the need of any prior pretreatment. The method can be a good alternative of choice for the determination of BSA and HSA.