Analytical Sciences

A Highly Sensitive and Rapid Assay for Protein Determination in Human Urine and Penicillin Using a Rayleigh Light-Scattering Technique with Benzeneazo-8-acetylamino-1-naphthol-3,6-disulfonic Acid Sodium Salt

Qin WEI,* Dan WU,*^,** Yan LI,* Bin DU,* and Jun Hong WANG*

*School of Chemistry & Chemical Engineering, Jinan University, Jinan 250022, China
**Key Laboratory of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China

A simple and sensitive method was conducted for the determination of trace amounts of proteins with benzeneazo-8-acetylamino-1-naphthol-3,6-disulfonic acid sodium salt (azophloxine, AP) using a Rayleigh light-scattering (RLS) technique. At pH 2.60 and in the presence of an emulsifier OP microemulsion, the RLS of AP can be greatly enhanced by proteins, owing to the interaction between AP and protein. The enhanced intensity is proportional to the concentration of proteins. Four proteins, including bovine serum albumin (BSA), human serum albumin (HSA), lysozyme (Lys) and γ-globulin (γ-G) have been tested. For example, the linear range of BSA was 0 - 0.06 µg mL^-1 with detection limits of 2.38 ng mL^-1. The method was applied to the analysis of protein in human urine and penicillin samples with satisfactory results. The relative standard deviation was in all instances less than 4.0%, and the recovery was in the range of 97.5 - 104%.

J-STAGE: View this article in J-STAGE