Synchronous determination with double-wavelength by RP-HPLC-UV and optimization of ultrasound-assisted extraction of phenolic acids from Caragana species using response surface methodology.

The utilization of Caragana korshinskii Kom. (CK) is currently concentrated on its ecological and fuel functions. Little attention has been devoted to the analysis of their phenolic acid (PA) components. To obtain more data for further utilization of CK, a new analysis protocol was tested to determine PAs synchronously by RP-HPLC-UV with double-wavelength (280nm and 320nm) detection. Specifically, separation of PA components was performed on a Hypersil Gold C reverse phase column with gradient elution. A four-factor-three-level Box-Behnken design was implemented for optimization of PA extraction. The results demonstrated that CK were rich primarily in chlorogenic acid, vanillic acid, caffeic acid and rosmarinic acid. The total content of PAs in CK leaves was the highest compared with its other parts. The distribution of total flavonoid content of CK was leaves>flowers>bark, while that of the total phenolic content of CK was flowers>leaves>bark.