[Determination of 10 phenolic compounds in vegetables by high performance liquid chromatography].

Objective: To establish a high performance liquid chromatography(HPLC) method for determination of flavonoids(epicatechin, L-epicatechin, quercetin, luteolin and kaempferol) and phenolic acids(gallic acid, chlorogenic acid, caffeic acid, p-coumaric acid, and ferulic acid) in vegetables.

Methods: Phenolic compounds were isolated by ethanol-water(1∶1, V/V) from homogenized vegetable samples under ultrasonic extraction at 50 ℃ for 10 min. The supernatant after centrifugation was dried and re-dissolved, which was eluted with Symmetry C_(18)(4.6 mm× 250 mm, 5 μm) chromatographic column at 280 nm wavelength, and quantified by external standard method.

Results: The 10 phenolic compounds could be separated within 40 min, with linear correlation coefficients greater than 0.999. The detection limit was 0.006-0.034 μg/g, and the limit of quantitation of the method was 0.020-0.100 μg/g. The recoveries of phenolic compounds in the three vegetables were 57.7%-96.8%, and the relative standard deviation of recoveries were less than 11.3%(n=6). The composition and concentration of phenolic compounds in 25 kinds of vegetable samples were different, and the total concentration of phenolic compounds in brassica vegetables were the highest.

Conclusion: The method is sensitive, accurate and reproducible, and is suitable for the determination of phenolic compounds in vegetables.