Liquid chromatography-electrospray ionization mass spectrometry(LC/(- )ESI-MS) has been applied to identify Ginkgolic acids, which are allergenic components existing in Ginkgo bilobal leaves. The complete baseline separation of four Ginkgolic acids by reversed phase argentation HPLC has been firstly achieved. Effects of the silver ion content in mobile phase and different temperature on the separation of Ginkgolic acis were studied. Addition of silver ions into the mobile phase decreased retention of Ginkgolic acids with an unsaturated side chain. A linear relation between lgk'and [Ag^+] was found. It also has been observed that temperature has great effect on selectivity of argentation HPLC. a possible explanation on the thermodynamic parameters is given. Resolutions between four Ginkgolic acids were above 1.5 under the optimum chromatographic conditions. The high selectivity of reversed phase argentation HPLC suggested that secondary chemical equilibrium in HPLC was an excellent method for separation of Ginkgolic acids homologous with different carbon atoms number and saturation.

Key words: SECONDARY REACTION, CHEMICAL EQUILIBRIUM, SILVER ION, SEPARATION, CHROMATOGRAPHY-MASS SPECTROGRAPHY, HIGH SPEED LIQUID CHROMATOGRAPHY, GINKGO, PHENOLIC ACID