Highly sensitive detection of melamine based on gemini surfactant using enhanced resonance Rayleigh scattering signals

We present here a resonance Rayleigh scattering (RRS) spectrum method for the determination of melamine at the nanogram level using a gemini surfactant (disodium 4-dodecyl-2,4′-oxydibenzenesulfonate, DDOF). It was found that DDOF could react with cationic melamine to form an ion-association complex, which induced the enhancement of RRS intensity and the appearance of a new RRS spectrum in acetate buffer (pH 3.6). The RRS spectral characteristics of the melamine-DDOF system, the optimum conditions of the reaction, and the influencing factors have been investigated. Under optimum conditions, the enhanced RRS intensity was proportional to the concentration of melamine in the range of 0.38–6.30 μg/mL. The method has high sensitivity, and the detection limit for melamine is 8.48 ng/mL. Furthermore, the reaction mechanism and the reasons of RRS enhancement were evaluated.

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► We report the reaction of DDOF with melamine by resonance Rayleigh scattering (RRS).
► A sensitive, simple, and rapid RRS method has been developed for melamine detection.
► The detection limit for melamine reached nanogram level.
► The method was applied successfully to the determination of melamine in milk sample.
► The possible mechanism for the RRS enhancement of melamine-DDOF system was discussed.