Reversed-phase argentation high-performance liquid chromatography in phytochemical analysis of ginkgolic acids in leaves from Ginkgo biloba L.

A reversed-phase argentation high-performance liquid chromatographic method has been achieved for the determination of ginkgolic acids. Liquid chromatography coupled with electrospray ionization (ESI) mass spectrometry in the negative ion mode is applied to identify ginkgolic acids from ginkgo leaves. The leaves are extracted with ethanol and then cleaned-up by extraction of analytes with hexane after addition of an acidified saturated solution of sodium sulfate and siliceous earth to the matrix solution. Ginkgolic acids are determined within 30 min on a C18 column with methanol-5% aqueous acetic acid (90:10) containing 0.03 mol l(-1) silver nitrate as eluent and with ultraviolet detection at 310 nm. Addition of silver ions as complexation agent into the mobile phase decreases retention time of ginkgolic acids with an unsaturated side chain. Four ginkgolic acids are successfully separated from each other and from other interfering components by the high selectivity of reversed-phase argentation HPLC, which is confirmed by the spectra identification. The average recovery of the method is around 97%. Good reproducibility is obtained with relative standard deviations varying from 2 to 5%.