Abstract: A new and fast dual-wavelength overlapping resonance Rayleigh scattering(DWO-RRS) method was developed to detect cadmium in preserved eggs.In a Tris-hydrochloric acid buffer medium at pH 5.72,cadmium (lⅡ) can be bound with fast green FCF-hexadecylpyridinium bromide to form a ternary complex.As a result,the new spectra of DWO-RRS appeared and its intensities was enhanced greatly.The largest and the second largest resonance Rayleigh scattering peak were located at 367 nm and 469 nm respectively.Under these two wavelengths,resonance Rayleigh scattering (RRS) intensity (△IRRs) was directly proportional to the cadmium (Ⅱ) mass concentration in a range of 0.004-0.22 mg/L.The methods had high sensitivity with the detection limit (3σ/S) of 1.3 ng/mL and quantitation limit of 0.012 mg/kg.The optimal conditions and the effects of coexistent substances of RRS method were investigated.In addition,the reasons for RRS enhancement and reaction mechanism of ternary complex were discussed.Results indicated that this assay had a high sensitivity and good selectivity.This simple,rapid,highly sensitive,accurate and new dual-wavelength scattering method had been proposed to determine trace cadmium (Ⅱ).The method was applied to determine the content of cadmium in a series of preserved eggs,the values of recovery and relative standard deviation (RSD) (n =5) were found in the ranges of 97.8％-102％ and 2.1％-2.6％ respectively.
2017, Vol. 43 
