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

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.

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.

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.

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