Abstract: A novel dual-wavelength Rayleigh light scattering (DWO-RLS) method for fast and accurate determination of the food additive cyclamate in cake, bread and biscuit was established. In the alkaline Tris-hydrochloric acid medium at pH 9.27, cyclamate reacted with brilliant green via electrostatic interaction to form an ionic association complex, leading to a distinctly enhanced RLS of the system, and producing a new RLS spectrum with two strong characteristic scattering peaks. The strong peak was located at 341 nm and the weak peak at 470 nm. There was a good linear relationship between the magnitude of enhanced RLS intensity (ΔIRLS) and cyclamate concentration in the range of 0.004 to 0.50 mg/L. The limits of detection (LOD) were 0.003 6 and 0.004 0 mg/L at 341 and 470 nm, respectively. The limits of quantitation (LOQ) of the DWO-RLS method were 1.05, 0.974 and 0.994 mg/100 g for cake, biscuit and bread, respectively. The recoveries of spiked samples were in the range from 97.3% to 103%, and the relative standard deviations (RSD, n = 5) ranged from 1.1% to 2.6%. The method was simple, rapid and highly sensitive, and it was applied to actual samples analysis with satisfactory results.

Key words: pastry; cyclamate; brilliant green; dual-wavelength; Rayleigh light scattering