A novel method for the determination of fluorescent whitening agent CBS in flour using flow-injection chemiluminescence based on a luminol-urea peroxide system

We have developed a novel flow-injection chemiluminescence analysis method to detect fluorescent whitening agent 2,2′-([1,1′-biphenyl]-4,4′-diyldi-2,1-ethenediyl)bis-benzenesulfonic acid disodium salt (CBS) for the first time. A luminol-urea peroxide chemiluminescence reaction system was adopted, and the instrumental and chemical parameters were respectively optimized. Under optimal conditions, the relationship between the relative chemiluminescence intensity and the concentration of CBS was fitted in linear mode, and satisfactory correlation coefficients were obtained (ΔI = 44.85C_CBS + 165.39, C_CBS, nmol L^-1, r = 0.9978). This assay is linear from 1 to 600 nmol L^-1, with limits of detection and quantification of 0.1 nmol L^-1 and 0.4 nmol L^-1, respectively. And the intra- and inter-day relative standard deviations are less than 1.5% and 4.5%. The proposed flow-injection chemiluminescence method had been successfully used in the determination of CBS in flour, and the recovery is 90.0-104.5%, which shows great potential in control of food safety. This method is sensitive and convenient, and could be comparable with others. Finally, a possible mechanism of chemiluminescence emission was also investigated.