Abstract:

A fluorescence method based on hypochlorous acid azo cleavage was established for the rapid determination of metanil yellow which was a prohibited ingredient in cosmetics. Hypochlorous acid was used as a fluorescence transfer initiator to trigger the conversion of the fluorescence emission signal of metanil yellow to achieve the rapid detection. By exploring the factors such as solvent, pH and reaction time, the optimal detection system was obtained. The results showed that metanil yellow showed a strong fluorescence emission at 345 nm with an excitation wavelength of 270 nm in acetonitrile-PBS buffer （V/V=9:1） solution at pH of 7. With the addition of hypochlorous acid, the fluorescence emission was quenched and a strong fluorescence emission appeared at 395 nm. The reaction time at room temperature was less than 40 min. The linear range of detection was 0.2-32 μg/mL, and the correlation coefficient was r²=0.993 9. The limit of detection was 0.2 μg/mL, and the method had good specificity. The average recovery in real samples was 90.5%-112.6% with the RSD less than 4.54%.

Key words: metanil yellow, hypochlorous acid, fluorescence determination, cosmetics