Flow injection-chemiluminescence determination of paraben preservative in food safety Original Research Article

The determination of a group of parabens including methylparaben, ethylparaben, propylparaben, and butylparaben using flow injection analysis technique with chemiluminescence detection has been carried out. The method is based on the enhancement by parabens of cerium(IV)-rhodamine 6G chemiluminescence reaction in sulfuric acid medium. Under the optimized conditions, the linear range of 4.5 × 10−10 to 1.5 × 10−7, 3.0 × 10−9 to 5.0 × 10−7, 5.0 × 10−9 to 1.0 × 10−6, and 8.0 × 10−9 to 8.0 × 10−7 g ml−1 and the detection limit of 3.4 × 10−10, 2.0 × 10−9, 2.0 × 10−9, and 5.0 × 10−9 g ml−1 were obtained for methylparaben, ethylparaben, propylparaben, and butylparaben, respectively. The relative standard deviations were less than 2.0%. The method shows higher sensitivity than most of the reported methods, which also require preconcentration or derivatization. It was successfully applied to the determination of ethylparaben in soy sauces without tedious pretreatment. The possible mechanism of this chemiluminescence reaction has been proposed due to that cerium(IV) was reduced by the products hydrolyzed by parabens to the excited-state cerium(III) in sulfuric acid medium and then energy was transferred from cerium(III)* to rhodamine 6G to form the excited-state rhodamine 6G, emitting light.