Use of cetyltrimethylammonium bromide as a simple probe for rapid determination of emodin by resonance light scattering technique.

Abstract A new resonance light scattering (RLS) method for emodin determination with cationic surfactant cetyltrimethylammonium bromide (CTAB) as probe has been developed. In Britton–Robinson buffer (pH 6.5) medium, emodin reacted with cationic surfactant CTAB and formed the emodin–CTAB complex. The complex aggregated together through hydrophobic forces and causing great enhancement of RLS signals with the maximum peak located at about 350 nm. The enhanced RLS intensities were found to be proportional to the concentration of emodin in the range of 0.54–9.72 μg ml −1 with the detection limit (3 σ ) of 10.3 ng ml −1 . In this work, the characteristics of RLS, absorption, fluorescence spectra of the system were studied. The optimum reaction condition and the influencing factors on the RLS signal were investigated in detail. The proposed method was applied to the analysis of emodin in synthetic samples and human urine with satisfactory results. Furthermore, the forms of the substances under the experimental condition and the mechanism of the reaction were discussed in detail.