Determination of Sunset Yellow Based on Its Quenching Effect on the Fluorescence of Acridine Orange

Acridine orange (AO) is widely applied as an organic fluorescent probe. In this work, AO was reacted with sunset yellow (SY) to form an ion-association complex in pH 3.4 Britton-Robinson (BR) buffer solution medium. This resulted in the fluorescence quenching of the former and helped to detect the latter with the maximum excitation wavelengths (λ_ex) and emission wavelengths (λ_em) near 490 and 530 nm, respectively. The assay exhibits high sensitivity and selectivity with a detection limit of 0.002 μmol L^-1 and the remarkable quenching of fluorescence was proportional to the concentration of SY in the range of 0.008 - 9.0 μmol L^-1. Herein, this finding was utilized to develop a new strategy for simple, rapid, sensitive and selective detection of SY by combining AO based on fluorescence quenching. In addition, the optimum reaction conditions and the effect of foreign substances were studied. The reasons for fluorescence quenching were also investigated, which showed the quenching of fluorescence of AO with SY was a static quenching process. Furthermore, the proposed method was applied in a real sample analysis with satisfactory results.