| Abstract: | A reverse-phase HPLC-DAD method was developed for simultaneous quantification of ten phenolic acids (caffeic acid, chlorogenic acid, neochlorogenic acid, 4-O-caffeoylquinic acid, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid methyl ester, 3,4-O-dicaffeoylquinic acid methyl ester, and 4,5-O-dicaffeoylquinic acid methyl ester) in the dried flower buds of Lonicera japonica Thunb. (Lonicerae Japonicae Flos; LJF). An optimal sample preparation method was established as 30-min ultrasonication with 100 times 50% (v/w) ethanol aqueous solution based on the orthogonal test results. The chromatographic separation of the ten phenolic acids was achieved with an AQ-C18 column (4.6 mm×250 mm, 5 µm) and a gradient elution of acetonitrile, methanol and 0.1% formic acid aqueous solution within 55 min. All calibration curves showed good linearity (r2>0.999) within test ranges. The average recoveries were in the range of 98.57%-103.22% with RSD less than 3%. The method developed was accurate, sensitive and reproducible for determination of ten phenolic acids in LJF. |
