Rapid and sensitive determination of proteins with Eriochrome Red in the presence of anionic surfactant by multi-spectroscopic methods

A new high-sensitivity detection of protein assay at the nanogram level is proposed based on multi-spectroscopic methods including resonance light scattering (RLS), atomic force microscopy (AFM), ultraviolet spectra (UV) and fluorescence spectra etc. Under the optimum conditions, the amplified RLS signals of anionic azo dyes Eriochrome Red B (ERB) in the presence of anionic surfactant sodium dodecyl sulphonate (SDS) was in proportion to the concentration of proteins in the range of 0.0–3.5 mg L−1 and 3.5–12.5 mg L−1 for bovine serum albumin (BSA), 0.0–2.0 mg L−1 and 2.0–8.0 mg L−1 for human serum albumin (HSA). The detection limits were 4.2 ng mL−1 and 2.7 ng mL−1, respectively. The method was satisfactorily applied to the measurement of total protein in human serum samples and a high-sensitivity was achieved.