Determination of Rutin in Tartary Buckwheat by Ultrasonic Extraction Combined with Flow-Injection Liquid Drops Spectrofluorimetry

On the basis of reaction of rutin with Al³⁺ to form fluorescent complex, a new method for determination of rutin in tartary buckwheat by ultrasonic extraction combined with flow-injection liquid drops spectrofluorimetric was established. 10 mL methanol was added to 2.000 0 g of sample and mixed well. The mixture was ultrasonically extracted for 15 min and centrifuged at 6 000 r·min^-1 for 5 min. After the supernatant was moved, the residue was extracted for twice with the same process. Then the combined supernatant were rotary evaporated to remove methanol. The sample residue was dissolved with 90% (φ) ethanol solution. After filtering, 5 μL of 0.1 mol·L^-1 Al(NO₃)₃ solution was added and the sample solution was made up to 10.0 mL. After settling down for 60-70 min, the sample solution was flow-injected at 4-5 mL· h^-1 and the fluorescence intensity of was detected at λ_ex 239 nm and λ_em 507 nm. The complex ratio of Al³⁺:rutin is 1:2. Linear relationship was found between fluorescence intensity and mass concentration of the complex in the range of 0.10-5.00 mg·L^-1, detect limit (3s) was 0.02 mg·L^-1. Recovery was between 86.0% and 104%, and RSDs (n=5) were between 3.1% and 6.1%. The method was suitable for the conventional determination of rutin in tartary buckwheat.